Once absorbed through either Inhala- tion or 1ngest1on, the dlchlorobenzenes are rapidly distributed to many tissues by the systemic circulation, Including adipose, kidney, liver, lung, heart, brain and muscle tissues. Distribution 1s primarily to adipose tissue, which has Initial levels times the blood concentrations and to lung and kidney tissues to a greater extent than liver, muscle and plasma.
Single-dose and repeated exposures by both Inhalation and 1ngest1on show similar patterns of distribution. Elimination of the dlchlorobenzenes and their metabolites occurs within days after exposure, although elimina- tion from adipose tissue 1s slowest and 1,2-d1chlorobenzene and metabolites are eliminated slightly more rapidly than 1,4-d1chlorobenzene.
The dlchlorobenzenes are primarily metabolized by hydroxylatlon to their respec- tive dlchlorophenols, which are excreted 1n the urine 1n the form of glucu- ronlc and sulfate conjugates. Some metabolites are excreted 1n the bile, although the majority are then reabsorbed by the enterohepatlc pathway and reexcreted 1n the urine. Intermediates of the metabolism of 1,2-d1chloro- benzene, possibly arene oxides, bind to liver protein and may be Involved 1n the Induction of hepatotoxldty.
From the available data, 1t appears that metabolism 1n at least three animal species has a common first step, the production of an arene oxide Intermediate. Subsequent metabolic steps, however, vary among the species examined, at least for the most studied Isomer, 1,2,4-tr1chlorobenzene. In general, the pharmacoklnetlcs of the trlchlorobenzenes are similar to those described for the other halogenated aromatlcs.
These compounds are UpophlUc and their metabolism and excretion depend on conversion to polar metabolites. In addition, their UpophlUc character provides for ready absorption from the gastrointestinal tract and Initial distribution to the more highly perfused tissues, particularly the liver, after which they are either metabolized and excreted or redistributed to adipose tissue or skin. Additional experiments are needed to clarify the relationship of these studies to the metabolism of trlchlorobenzenes In humans.
No studies describing the absorption, distribution, metabolism or excre- tion of 1,2,3,4-, 1,2,3,5- or 1,2,4,5-tetrachlorobenzene following Inhala- tion exposure were located 1n the available literature. The pharmaco- klnetlcs of the tetrachlorobenzene Isomers following oral administration 1s well characterized In rabbits, but not 1n other animal species.
The Upo- phlUc characteristics of the tetrachlorobenzene Isomers would allow effi- cient transepithellal absorption at the gastrointestinal and respiratory surfaces. Once absorbed, the tetrachlorobenzene Isomers administered orally to rabbits were rapidly accumulated 1n fat, metabolized primarily to tetra- chlorophenols and conjugated partly as glucuronldes and ethereal sulfates or eliminated unchanged 1n the expired air or feces.
Although studies of the absorption of pentachlorobenzene Indicated that absorption does occur through the gastrointestinal tract, the rate or extent of absorption has not been determined. Absorption resulting from Inhalation has not been studied, and absorption from dermal exposure was found to be rather poor 1n rats. Once absorbed, pentachlorobenzene 1s dis- tributed to many tissues, with the highest levels appearing 1n fat and bone marrow. A study 1n rats demonstrated that transport across placental membranes occurred readily and that accumulation of pentachlorobenzene 1n the fetus 1s highest 1n the liver.
No studies were encountered that described the distribution of pentachlorobenzene after Inhalation or dermal exposure. The metabolism of pentachlorobenzene 1s not fully understood, but some studies suggested that metabolic activity other than the hepatic cytochrome P, xenoblotlc metabolizing system may be Involved. Metabolism appeared to be primarily via oxidation to two major metabolites, pentachlorophenol and 2,3,4,5-tetrachlorophenol, which were excreted 1n the urine.
Metabolism and excretion occurred at a slow rate; an estimated elimination half-life for a single dose 1n primates was months. No Information was present 1n the available literature on hexachlorobenzene metabolism following Inhalation or topical application. Absorption of hexa- chlorobenzene from the Intestinal tract appeared to depend on the vehicle used during test material administration.
Similarly, only small amounts of hexachlorobenzene metabolites were detected 1n feces, whereas most of the metabolites were excreted 1n the urine together with small amounts of unchanged hexachlorobenzene. There are Indications that females produce and excrete more hexachlorobenzene metabo- lites than do males. The excretion of hexachlorobenzene from treated animals 1s slow and occurs mainly through the feces with relatively little being excreted 1n the urine.
It 1s characterized by an Initial rapid phase followed by one or more slow phases. This slow phase of excretion can be enhanced by the administration of mineral oil, paraffin or n-hexadecane. Both biliary and Intestinal excretion contribute to fecal excretion. A three-compartment mammlllary model has been reported for the behavior of hexachlorobenzene 1n beagles and rhesus monkeys following 1.
Injection of a single dose. Radioactivity was not detected 1n exhaled air following l. Injection of 14C-hexachlorobenzene. Hexachlorobenzene has been detected 1n the milk of nursing mammals. Effects on Humans. No ep1dem1olog1c studies regarding the effects of exposure to monochlorobenzene are available.
Human exposure to mono- chlorobenzene by Inhalation or by accidental 1ngest1on can cause neurotoxlc effects. It 1s not known 1f the effects are reversible after long-term exposure or 1f there are other sites of toxldty. Ep1dem1olog1c data on dlchlorobenzenes are Insufficient to evaluate dose-response association.
Possible chronic effects of exposure to the dlchlorobenzenes are Indicated by case reports of the chronic exposure of Individuals, I. Although the exposures 1n these cases are not well defined 1n time and often Involve other toxic substances, together they suggest a common pathologic action of the dlchlorobenzenes on bone marrow and other organs of the blood-forming system.
This study did not establish an association between chromosomal alterations and the pathologic changes that characterize the case studies. Human exposure to 1,2,4-tr1chlorobenzene at ppm causes eye and respiratory Irritation. The only other data on human exposure are Individ- ual case reports of aplastlc anemia of persons exposed occupatlonally or domestically.
Only one ep1dem1olog1c study was available regarding the effects of the tetrachlorobenzenes on humans and this study examined peripheral lymphocytes for chromosomal abnormalities 1n blood. The blood was collected from Hungarian workers engaged 1n the production of 1,2,4,5-tetrachlorobenzene. There were observed chromosome aberrations 1n the lymphocytes; however, no airborne concentrations or exposures were determined.
No ep1dem1olog1c or case studies of effects on humans resulting from exposure to pentachlorobenzene were available for review. A few ep1dem1olog1c studies with occupatlonally-exposed workers have been reported, together with studies conducted 1n Turkey and 1n the United States I.
These studies qualitatively support the toxlclty of hexachlorobenzene, but give Uttle dose-response Information. The exposure of humans to hexachlorobenzene 1n Turkey during caused an epidemic of hexachlorobenzene-lnduced porphyrla cutanea tarda PCT , also known as porphyrla turdca, which 1s manifested by disturbed porphyrln metabolism, cutaneous lesions and hyperp1gmentat1on.
The authors estimated that from 0. A correlation was found between hexachlorobenzene levels In blood and the number of years worked In a chlorinated solvents plant. An ep1dem1olog1c survey conducted with 86 residents 1n the vicinity of this chlorinated solvents plant showed elevated hexachlorobenzene residues In plasma. Higher levels of hexachlorobenzene residues were found 1n males than 1n females, but these were not associated with race or food consumption.
Mammalian Toxicology. Monochloroben- zene Is also toxic by the oral or parenteral routes. Systemic effects of acute toxic doses Include kidney damage. Subchr'onlc Inhalation exposure at 1. A set of sim- ilar studies were conducted 1n mice and rats for 2 years and resulted 1n some Increased mortality 1n the male monochlorobenzene exposed groups when compared with controls. Only equivocal evidence for mild monochlorobenzene- Induced hepatocellular necrosis was found 1n rats.
Although one study 1n Streptomyces antlblotlcus found monochlorobenzene to Induce reversion to vitamin B, prototrophy and one study 1n Saccharo- myces cerevlslae showed Induction of DMA damage, several other studies using bacterial, fungal and mammalian tissue culture systems were negative.
Repeated exposures to monochlorobenzene at 2. These effects 1n dogs, however, were seen only at levels sufficiently toxic that the dogs died or were moribund. Studies of the acute and subchronlc toxldty of the dlchlorobenzene "Isomers Indicate that generally these compounds have similar target organs and effects.
The subchronlc oral toxlclty studies 1n rats provide two estimates of no-observed-effect level NOEL values: 0. Acute and subchronlc Inhalation studies of dlchloroben- zenes Indicate similar toxic effects and target sites as seen 1n the oral studies. Studies of the mutagenlc activity of dlchlorobenzenes show little or no activity 1n a range of bacterial systems, Including Salmonella, with and without metabolic activation.
However, these studies were lacking 1n exper- imental detail. No evidence of carcinogenic activity was found under the test conditions. The carcinogen- Id ty of l,4-d1chlorobenzene was tested 1n two rodent species using long- term Inhalation exposure. Again, no evidence for carc1nogen1c1ty was noted. Since neither study may have used the maximum tolerated dose, the evidence must be considered Inadequate for developing conclusions concerning the carc1nogen1c1ty of 1,2- or 1,4-d1chlorobenzene 1f the IARC criteria for classifying carcinogens are used.
The effects 1n mammals of acute exposure by various routes to trlchloro- benzenes Include local Irritation, convulsions and death. Livers, kidneys, adrenals, mucous membranes and brain ganglion cells appear to be target sites with effects Including edema, necrosis, fatty Infiltration of livers, Increased organ weights, porphyrln Induction and mlcrosomal enzyme Induction. Quantitative data on the toxic effects of trlchlorobenzene following subchronlc exposure by various routes were obtained 1n a variety of species.
In general, these studies Indicate that the liver and kidney are target organs. One study Identified Subchronlc dermal exposure resulted 1n mild to moderate Irritation. One chronic study on the effects of trlchlorobenzene 0. Results of two reports on mutagenlclty tests with Salmonella tvphlmurlum test strains were negative. However, this test system 1s generally Insensi- tive to chlorinated compounds. One carc1nogen1c1ty study, a 2-year skin painting study In mice, failed to demonstrate a conclusive tumor1gen1c effect.
A multlgeneratlon study of the reproductive effects of oral expo- sure of rats to trlchlorobenzene failed to show effects on reproduction. Oral teratogenldty studies 1n rats showed mild osteogenlc changes 1n pups and significantly retarded embryonic development as measured by fetal growth parameters. The only mammalian toxicology data available for tetrachlorobenzenes are the result of oral exposures.
Subchronlc oral exposure of rats and rabbits to 1,2,4,5-tetrachlorobenzene resulted In statistically significant effects on biochemical parameters, Including retlculocytosls, Increased blood chollnes- terase activity, erythremla and an Indication that glycogen formation was Impeded; at higher doses of 1,2,4,5-tetrachlorobenzene, rats also had Increased kidney and liver weights, and renal and hepatic hlstologlc changes. However, because only an abstract of the study was available, experimental details were too sparse to permit an evaluation of this negative result.
These results were reported 1n an abstract with Insufficient experimental detail. Also, a negative result for chlorinated compounds 1n the Salmonella rever- sion assay 1s not unexpected. No Information was available regarding the carclnogenlclty of any of the three tetrachlorobenzene Isomers In either animals or humans.
The tetrachlorobenzene Isomers have been found to Induce appreciable maternal toxldty, mild fetotoxlclty and negligible teratogenlcl ty 1n rats following oral administration. Also, 1t was demon- strated that pentachlorobenzene caused an Increase 1n the liver content of cytochrome P, mlcrosomal drug metabolizing enzymes and mlcrosomal proteins. A subchronlc feeding study Indicated that the primary toxic effects are on the liver and kidneys, although slight changes 1n some hematologlc param- eters e.
No mutagenlc activity was detected 1n five strains of Salmonella, typhl- murlum when tested at five unspecified concentrations of pentachlorobenzene 1n the presence and absence of rat Hver mlcrosomes Induced by Aroclor These results were reported 1n an abstract with Insufficient experimental details presented.
A negative result 1s not unexpected, because the Salmo- nella test system has been found to be generally Insensitive to chlorinated compounds. Studies also have shown that pentachlorobenzene 1s capable of causing reproductive and developmental effects.
Female rats fed diets containing pentachlorobenzene during mating and gestation produced Utters with reduced pup survival and body weights at weaning, and Increased Hver-to-body weight ratios. Subchronlc oral toxlclty studies with a number of mammalian species Indicated a significant Increase In liver and kidney weights 1n hexachlorobenzene-treated animals. Some studies have shown Increases 1n other organ weights as well. The livers from hexachlorobenzene-exposed animals have shown hlstologlc changes such as Irregular shaped and moderately enlarged liver mitochondria and Increases In the size of the centrllobular hepatocytes.
Chronic toxlclty studies revealed similar effects to those seen 1n the subchronlc studies, plus hexachlorobenzene associated life-shortening and various hepatic and renal pathologies. These subchronlc and chronic effects were usually dose- related. Other effects Included multiple alopecia and scabbing, together with neurologic effects 1n rats, mice and dogs.
A dose-related hlstopatho- loglc change 1n the ovaries of monkeys has also been reported. Increased porphyrln levels 1n the liver and 1n urine have been reported for all species studied except the dog. Hexachlorobenzene was found to cause the accumulation of B-H-stero1ds which Induce porphyrln biosynthesis and to Inhibit uroporphyrlnogen decarboxylases. The Inhibition of uropor- phyrlnogen decarboxylase appears to be from pentachlorophenol, a hexachloro- benzene metabolite. Indications are that females are more susceptible to hexachlorobenzene-lnduced porphyrla than are males, which may be related to the females estrogen levels and greater hexachlorobenzene metabolism.
Hexachlorobenzene was reported to produce a mixed-type Induction of cyto- chromes resembling that produced by a combination of phenobarbltal P and 3,4-benzpyrene P , In addition, the activities of several hepatic mlcrosomal enzymes were found to be Induced by hexachlorobenzene. Hexachlorobenzene possessed no detectable levels of mutagenlc activity 1n the Salmonella h1st1d1ne reversion assay. The chronic toxldty studies provide sufficient evidence of the carc1nogen1c1ty of hexachlorobenzene 1n animals since there was an Increased Incidence of malignant tumors of the liver 1n two species haemang1oendothel1oma In ham- sters and hepatocellular carcinoma 1n rats as well as reports of hepatoma 1n mice, rats and hamsters.
Hexachlorobenzene given to pregnant mice was found to produce cleft palates and renal agenlsls 1n exposed pups. Cer- tain chemicals were found to alter the toxldty of hexachlorobenzene 1n mam- mals, whereas hexachlorobenzene pretreatment was reported to Increase CC1, toxldty and alter the Immune responses of treated animals.
As the benzene ring Is Increasingly chlorinated there are physlochemlcal trends towards Increased melting points, boiling points, densities and log partition coefficients, and decreased volatility and water solubility of the compounds. A wide range and severity of chlorinated benzenes-Induced health effects have been reported In rodents and other laboratory animals. Some of these same effects have also been observed 1n chlorinated benzenes-exposed humans as well, but the human reports are not as extensive or complete as the animal studies.
A review of the animal chlorinated benzenes health effects literature also Indicates that there are some large data gaps existing for several of the chlorinated benzene Isomers, especially for 1,3-dlchloro- benzene, the trlchlorobenzenes and the tetrachlorobenzenes.
Adequate evidence of the carc1nogen1c1ty of the different chlorinated benzenes has only been shown for hexachlorobenzene. Hexachlorobenzene has been classified as a probable carcinogen 1n humans. These new data would refine the known Information and give scien- tists a better understanding of the effects of the chlorinated benzenes and their properties.
Some of the health-related data might become available as Indicated In 48 FR However, as the result of this document and Its review, the following research needs were Identified which would yield data that would provide further Information on the specific nature and health effects of the chlorinated benzenes, as well as help to resolve many remain- Ing unknowns. Further studies should be conducted to determine detailed pharmaco- klnetlcs of each of the chlorinated benzene Isomers I.
Further studies should be conducted to determine more thoroughly the long-term toxldty and, 1n some cases, the carc1nogen1c1ty of many of the chlorinated benzene Isomers, except for hexachloro- benzene where sufficient data already exists. Further mutagen1c1ty studies should be conducted on those chlori- nated benzene Isomers which do not have sufficient mutagenlclty data available.
Studies should be conducted to assess the potential of the chlori- nated benzenes to cause ONA damage. Teratogen1c1ty, fetotoxlclty and reproductive studies should be conducted using various routes of exposure, with emphasis on the Inhalation route, on all the chlorinated benzene Isomers. Studies should be conducted to assess for possible chlorinated benzenes effects on alterations to the endocrine, hematopoletlc and Immunologlc systems 1n humans and animals.
Further studies need to be conducted on the porphyrla-produdng properties of the chlorinated benzenes [I. Investigations need to be conducted Into the quantitative structure-activity relationships of the chlorinated benzenes with an effort to relate biological and health effects to physlochemlcal properties. Studies are needed to Identify the extent of human exposure from each of the chlorinated benzene Isomers and the relative contri- bution of the various environmental medlas to the total human exposure.
Exposure and health assessments of Indoor air pollution by chlori- nated benzenes need to be made. This Is Important especially for the dlchlorobenzenes which are present In household space deodor- ants and moth repellents, Epidemiclogic studies need to be conducted on Individuals who are occupationally exposed to the chlorinated benzenes, with particular emphasis on those adverse health effects already observed In the human and animal studies.
Further follow-up studies are needed concerning the health of the Turkish Individuals who were exposed to hexachlorobenzene In the 's, with particular emphasis on their cancer Incidences. The chemical structures of these com- 0 0 pounds are shown 1n Figure The chlorobenzenes are chemically very unreactlve compounds and are generally stable under ambient conditions 1n the laboratory.
Because of the electron-withdrawing character of the chlorine atom relative to carbon, the chlorobenzenes are highly resistant to electrophHlc attack e. U 1,4- CAS No. C NCI No. U CAS No. U TSL No. A description of each of the chlorinated benzenes follows. Honochlorobenzene, which 1s the most polar of the chlorinated benzenes, 1s a colorless, volatile liquid with a pleasant almond-Uke odor that 1s classified as a flammable liquid by the U.
Department of Transportation NLH, a. It 1s mlsclble 1n all proportions 1n ethyl alcohol and dlethyl ether, and 1s very soluble 1n car- bon dlsulflde and benzene NLH, a. No established trade specifications exist for monochlorobenzene. It possesses a distinctive odor that 1s noticeable at concentrations between 30 and 60 ppm NLM, a. Its water solubility was reported as 0. Hexachlorobenzene 1s sparingly soluble 1n cold alcohol and soluble 1n benzene, chloroform and ether NLM, a. Impure commercial preparations may contain pentachlorobenzene , ppm , octachlorodl- benzo-p-d1ox1n 0.
This Implies that the more chlorinated the chlorinated benzene, the more likely Is photodegradatlon at sea level by sunlight. Diagnostic Infrared absorptions for all the chlorinated benzenes occur around 3. All the proton NMR aromatic signals for chlorinated benzenes 1n carbon tetrachlorlde or deuterated chloro- form solvents occur between 6.
Thus, specific 1on monitoring using the molecular Ions and M peaks 1s possible, Increasing the sensitivity of analysis. The atmospheric chemistry of chlorobenzenes has been studied under laboratory conditions. D1ll1ng et al. Kanno and Nojima Irradiated monochlorobenzene with light from a xenon lamp 1n the presence of nitric oxide and air and found the products to be chlorinated nltrobenzenes and nltrophenols.
Uyeta et al. Using higher A concentrations ppm chlorobenzene and ppm NO , Kanno and Nojlma found similar rates of degradation and Identified one chloronltroben- zene and three chloronltrophenols as products. Rates of reaction of chlo- robenzene with hydroxyl radical Anbar and Neta, and singlet oxygen Graedel, are also available which allows half-life estimations of 0.
Yanohlhara et al. One study has examined the possibility of photocatalyzed degradation of the chlorinated benzenes. Oliver et al. Degrada- tion of the dlchlorobenzene occurred only 1n the titanium oxide solution, possibly because of a shielding of the chemical from the light by the other sediments or as a consequence of a catalytic effect of titanium oxide, and did not occur 1n natural sediment systems. Korte et al. The Hustert et al.
The purge and trap method 1s the most common method used for the sampling of volatile chlorobenzenes 1n water. Headspace analysis using GC with flame 1on1zat1on detection or electrolytic conductiv- ity detection are also used for analysis of aqueous samples. Methods that are slightly modified from the analytical procedures for aquatic samples are used for the analysis of chlorobenzenes 1n soil, food and human tissues. The following sections provide examples of these analytical methods.
Chemical Analysis 1n A1r. Krost et al. The sample was then thermally desorbed and the vapors passed through a cryogenlcally cooled trap and subsequently Introduced Into a gas chromato- graph-mass spectrometer GC-MS. Estimated detection limits for three chlorobenzenes were as follows: monochlorobenzene, 2. A similar method has been used for the monitoring of mono- and dlchlorobenzenes by Barkley et al.
Lewis and MacLeod have developed and evaluated a portable low- volume air sampling system for Indoor air monitoring of semlvolatlle organic chemicals. Two types of sampling cartridges were used to sample for chloro- benzenes. Using polyurethane foam PUF , a mean collection efficiency of For five 0. However, using a dual-sorbent trap consisting of a 0.
Theoretical detection limits, using GC-electron capture detection, are expected to be at least one order of magnitude lower 1n the range of 0. Storage stability of the PUF cartridges was tested under adverse storage conditions. Billings and Bldleman reported that hexachlorobenzene was very poorly retained by porous PUF, but efficiently collected by Tenax-GC. Langhorst and NestMck used an air sampling tube packed with two sections of Amberllte XAO-2 resin separated by a sllanlzed glass wool plug to collect the chlorobenzenes.
The adsorbent was desorbed with carbon tetrachlorlde and analyzed by GC using a photo1on1zat1on detector. Thompson et al. They described a method for determining m1crogram-per-cub1c meter levels of monochlorobenzene 1n air using sampling cartridges containing Porapak N, followed by elutlon with methanol and analysis by GC. This technique reportedly allows for greater flexibility. Results are reproducible at various relative humidity levels and varying concentrations of carbon dioxide.
Advantages over thermal desorptlon techniques Include ease of operation and the ability to use various columns to achieve analytical precision. NIOSH has developed sampling and analytical methods for occupa- tional air monitoring for monochlorobenzene, 1,2-d1chlorobenzene and 1,4- dlchlorobenzene. All three methods Involve trapping the compound 1n a char- coal tube, desorblng the analyte with carbon dlsulflde, and analyzing the sample 1n a gas chromatograph using flame 1on1zat1on detection.
Chemical Analysis 1n Water. The purge-trap method 1s the most commonly used method for analyzing volatile organlcs 1n water. Otson and Williams evaluated the use of the dynamic headspace or the purge-trap method 1n combination with GC technique for a number of organlcs Including monochlorobenzene and dlchlorobenzene.
The purge-trap technique 1s also recommended by U. EPA Method for the determination of mono- and dlchlorobenzenes 1n wastewater. Minimum detectable quantities using electrolytic conductivity detection were 0. The static headspace technique was employed by Otson et al. The purge-trap technique does not provide quantitative recoveries for compounds with low volatilities, such as trlchlorobenzenes and higher chlorinated benzenes.
The U. EPA Method has recommended the use of Flor1s1l column chromatography as a cleanup step before the quantification of the samples by GC with electron capture detector. This recommended method 1s applicable for the determination of d1-, trl-, tetra-, penta- and hexa-chlorobenzene 1n drinking water and wastewater. EPA, A method for the determination of hexachlorobenzene 1n son and chemical waste disposal site samples has been developed by DeLeon et al.
The procedure Involves methane extraction followed by temperature- programmed GC analysis using electron capture detection. Recoveries of samples spiked at the 10, and pg levels were The solvent extraction method was used by Lopez-Avlla to determine chlorobenzenes 1n sediment samples. In this method, the solvent extract was subjected to acid-base fractlonatlon. The final separation and quantification was accomplished by GC-MS. Chemical Analysis 1n F1sh and Other Foods. H1att compared three analytical methods used to quantify mono- chlorobenzene levels 1n fish tissue.
This modification provided reproducible purging efficiencies. A similar modified purge-trap method has been used by Easley et al. The determination of trlchlorobenzenes and other higher chlorinated ben- zenes in fish samples can also be accomplished by a solvent extraction method. In one method, Kuehl et al. Murray et al. This method involves solvent extraction and GC analysis using electron capture detec- tion.
A mean recovery of The solvent extraction method was also used by Tessari and Savage for the determination of hexachlorobenzene In human milk. In this method, the extract was subjected to Flor1s1l and silica gel column chromatographlc cleanup, followed by GC-electron capture detection. A similar solvent extraction method, followed by solvent partitioning and Flor1s1l column cleanup, and GC-electron capture detection was used for the quantification of hexachlorobenzene In different crops from 37 states Carey et al.
Blood and urine samples have also been analyzed for the chlorobenzenes by GC using photo1on1zat1on detection Langhorst and Nestrlck, A method of hexachlorobenzene determination and confirmation 1n adipose tissue has been described by Watts et al. In this method, the solvent extract 1s subjected to a Florlsll cleanup and one-fraction elutlon.
Hexachlorobenzene 1s determined by direct GC with electron capture detec- tion. Confirmation Is made by analysis of the b1s-1sopropoxytetrachloroben- zene derivative, which 1s formed by reaction with Isopropanol. Average recoveries ranged between This method 1s particu- larly useful for the determination of hexachlorobenzene 1n the presence of M1rex.
For more volatile chlorinated benzenes, such as mono- and dlchlorobenzenes, the modified purge-trap method 1n combination with capillary GC and flame 1on1zat1on detection or preferably more specific detection method can be used Michael et al. SUMMARY The chlorinated benzenes are a group of compounds 1n which chlorine substltuents have been added to a benzene ring yielding a total of 12 1so- meMc forms.
They are chemically unreac- tlve and exist as liquids or solids at environmental conditions. Analysis of airborne chlorobenzenes 1s usually accomplished by adsorption onto sorbent cartridges, followed by thermal desorptlon and analysis by GC. For water samples, the purge-trap method Is used to concentrate the volatile halogenated benzenes before analysis by GC. For less volatile chlorinated benzenes, solvent extraction followed by column chromatographlc cleanup of the extract and GC with electron capture detection, 1s the most commonly used method for the Isolation, detection and quantification.
Methods similar to those used for wastewater samples are commonly used for the analysis of chlorinated benzenes In biological matrices. The output product 1s then purified by distillation, and the Isomers are Isolated by fractional distillation or crystallization.
EPA, provides production data on the chlorinated benzenes for Individual facilities. Total yearly production data are published for high-volume, synthetic chemical Intermediates by the U. PPG Industries, Inc. Hontrose Chemical Corp. Monsanto Co. Montrose Chemical Corp. Dover Chemical Corp. Chem South Corp. EPA, bSource: U. ITC, CA11 production at this site was processed within the facility and was not distributed outside the facility as a chemical or in a mixture.
The names of the chloroben- zene manufacturers given 1n Table are slightly different from those given in Table , because Table 11st only the manufacturers as of January, More recent Information Indicates that the Dow Chemical Corporation no longer produces any chlorinated benzenes, that Standard Chlorine Chemical now produces trlchlorobenzenes mixed Isomers , and that pentachlorobenzene is no longer produced In the U.
As mentioned already, hexachlorobenzene 1s not manufactured commercially in the United States but does occur 1n waste streams during the production of some organic chemicals e. USE Chlorinated benzenes are used 1n the manufacture of Intermediates in the production of organic chemicals, Including other chlorinated benzenes, herbicides, pesticides, dyes and rubber chemicals and as dye carriers, process solvents, pesticides, fungicides and deodorizing agents U.
A summary of these uses 1s presented 1n Table In general, these releases would occur during the manufacture and transport of chlorobenzenes, through their use as pesticides, solvents and other Industrial and consumer products, and through the disposal of wastes from the manufacturing process. Estimates of releases Table have been made for monochlorobenzene, dlchlorobenzenes and trlchlorobenzenes.
Honsanto Co. Standard Chlorine Chem. S-Tr1chlorobenzene: Southland Corp. EPA, DOT and slllcones; as a process solvent for methylene dllsocyanate, adheslves, polishes, waxes, Pharmaceuticals and natural rubber; as a degrading solvent. In the manufacture of 3,4-d1chloroan1Hne; as a solvent for a wide range Hawley, of organic materials and for oxides of non-ferrous metals; as a solvent carrier In production of toluene dllsocyanate; In the manufacture of dyes; as a fumlgant and Insecticide; In degreaslng hides and wool; 1n metal polishes; In Industrial odor control; In cleaners for drains.
As a fumlgant and Insecticide Hawley, As a moth repellent, general Insecticide, germicide, space deodorant; Hawley, In the manufacture of 2,S-d1chloroan1l1ne and dyes; as an Inter- mediate; 1n Pharmaceuticals; 1n agricultural fumlgants. Other than chemical Intermediate usage, the uses of this compound U.
EPA, are the same as 1,2,4-tMchlorobenzene. As an Intermediate In the manufacture of herbicides; as a dye carrier, U. EPA, as a dielectric fluid; as a solvent; as a heat-transfer medium. As a component In dielectric fluids; 1n the synthesis of fungicide. NA As an Intermediate for herbicides and defoliants; as an Insecticide; moisture-resistant Impregnant; 1n electric Insulation; In packing protection. In a pesticide used to combat oyster drills; as a chemical Intermediate.
As a fungicide; Industrial waste product In the manufacture of perchloro- ethylene, chlorinated solvents, pesticides and nltroso rubber. SUmak et al. Virtually all the monochlorobenzene used as a solvent In herbicide formulations Is probably released Into the atmosphere. Approximately 0. These four products and the estimated quantities of hexachloroben- zene produced are listed 1n Table Table shows the most recent official figures for quantities lost from Industrial sources, and quantities released Into the environment compared with total Industrial production 47 FR Levels 1n A1r.
Investigations of the occurrence of chlorobenzenes In air have been conducted 1n Japan and the United States utilizing both grab and sorbent cartridge techniques. These studies, which have Included the sampling of polluted air and urban and rural air, have reported the detection of monochlorobenzene, and various Isomers of d1-, tr1-, tetra- and hexa-chlorobenzenes. Analysis of Indoor air has Indicated the presence of monochlorobenzene and the dlchlorobenzenes; other studies have measured monochloro- and 1,4-d1chlorobenzene 1n occupational settings.
Horlta and Oh1 sampled ambient air for the determination of l,4-d1chlorobenzene levels at six central and suburban Tokyo sites 1n Japan and found concentrations ranging from 1. Determinations were also performed on "Indoor" samples from a closet, a bedroom and a wardrobe; these concentrations were times greater than the highest reported ambient levels.
PelUzzaM et al. Samples from each location were obtained from several sites at a given loca- tion and at numerous times. The samples were analyzed for monochlorobenzene and the d1- and trlchlorobenzenes. Table 1s a compilation of these data. Monochlorobenzene and the dlchlorobenzenes were also measured by WoJ1nsk1 et al. However since the methodology was different, the significance of this finding 1s uncertain.
Over a 5-month period, a total of samples were obtained at five sites that Included a mixture of Industrial, residential and semlrural locations. The results, reported by BozzelH and Kebbekus , Indicated the pres- ence of 1,2- and l,4-d1chlorobenzene at all sites.
The average concentra- tions trace amounts were averaged as the lower detection limit of 0. In a follow-up study, Harkov et al. Field studies were conducted by Singh et al. Table presents the results of the analysis. The atmospheric concentrations of the chlorinated benzenes around different locations In the United States have been measured by a number of other Investigators.
In a recent report, Brodzlnsky and Singh Integrated most of the available U. The levels of pentachlorobenzene and hexachlorobenzene 1n ambient air samples rarely have been reported. Considering their volatility, the abundance of these compounds 1n the atmosphere can be speculated to be lower than the other chlorobenzenes. However, tetrachlorobenzenes, pentachloro- benzene and hexachlorobenzene have been detected, but not quantified, 1n fly ashes from municipal Incinerators Elceman et al.
High volume air samples collected from Boston, Massachussetts, and Columbia, South Carolina, using a glass fiber filter and polyurethane foam trap were subjected to Interlaboratory analysis of hexachlorobenzene along with other parameters Bldleman, Concentrations of hexachlorobenzene at distances feet downwind from the plants ranged from 0.
The authors noted that the highest levels of hexa- chlorobenzene contamination were associated with the production of lower chlorinated hydrocarbons as opposed to the production of chlorine and herbi- cides, and that plants with onslte landfill and open pit waste disposal sites had the highest levels of airborne concentrations of hexachlorobenzene.
Chlorinated benzenes are also present 1n the air of occupational settings. Gabriel, LA PPG Lake Charles, LA Perchloroethylene, carbon tetrachlorlde, chlorine Perchloroethylene, carbon tetrachlorlde, methylene chloride, chlorine Carbon tetrachlorlde, perchlo- roethylene, chlorine Carbon tetrachloride Trlchloroethylene, perchloro- ethylene, chlorine Pentachloronltrobenzene, chlorine Atrazlne, propazlne, slmazlne Trlchloroethylene, perchloro- ethylene, vinyl chloride, vinyl 1dene chloride, chlorine, etc.
In a survey of three water treatment plants of the city of New Orleans, Louisiana, U. EPA a reported finding only one chloroben- zene, 1,3-d1chlorobenzene, at two of the plants. Analysis of these data and data on 52 other toxic chemicals Indicated that New Jersey groundwater has a similar pattern and degree of contamination as surface water.
Oliver and Nlchol sampled drinking water 1n three cities on Lake Ontario, both before and after chlorlnatlon. No Increase 1n the level of concentration was noted 1n these compounds after chlorlnatlon. The levels of chlorobenzenes In the drinking water of three cities bordering Lake Ontario are given 1n Table As part of a study of the contamination of drinking water by leachate from a pesticide waste dump site in Hardeman County, TN, Clark et al.
EPA survey of chemicals 1n private wells. In another study of possible contamination of drinking water by the disposal of toxic chemicals, Barkley et al. The chlorobenzenes have been Identified In wastewaters from Industrial processes and In Influents and effluents at municipal sewage treatment plants.
The author concluded that the Increase 1n the dlchlorobenzene levels was a result of chloMnatlon performed during the secondary phase of wastewater treatment. EPA survey of wastewater throughout the United States found that dlchlorobenzenes and trlchlorobenzenes occurred 1n discharges from Indus- trial and municipal plants Ware and West, Young and Hessan also reported the presence of several chlorobenzenes 1n the wastewater of major municipal facilities 1n southern California.
The frequency and range of concentrations found are summarized 1n Table Investigation of the occurrence of chlorobenzenes 1n food has been limited primarily to the measurement of hexachlorobenzene. This concern derived from Its use as a fungicide on the seeds of several food crops and from Its ability to bloaccumulate 1n the food chain. The bio- accumulation potential of hexachlorobenzene and the other chlorobenzenes 1s discussed 1n Section 5.
Johnson and Hanske reported the detection of hexachlorobenzene at levels of 0. Based on these and other data, FDA estimated the average dally Intake of hexachlorobenzene from foods 1n fiscal years and to be 0. Leonl and D'Arca , using analysis data on cooked foods served 1n the Italian Navy, estimated an aver- age dally Intake of 4.
In addition, these authors surveyed uncooked foods available to the public and found mean hexa- chlorobenzene levels ranging from none detected to The aver- age dally Intake of hexachlorobenzene from uncooked diets was calculated to be 4. Hexachloroben- zene has also been detected 1n Navy foodstuffs available 1n Japan Morlta et a!. Some Information on the presence of other chlorobenzenes 1n food was also available.
Morlta et al. Oliver and Nlchol reported detecting all Isomers of dlchlorobenzene, tr1- chlorobenzene, tetrachlorobenzene, pentachlorobenzene and hexachlorobenzene 1n trout from the Great Lakes. The highest levels were detected for penta- and hexachlorobenzene and the mean concentrations were 5.
Residues of pentachlorobenzene have also been found 1n oils, fats and shortening 0. Soil and Sediments. The study of soil contamination by chloro- benzenes has focussed on hexachlorobenzene, although more recent surveys have Included all the chlorobenzenes. Hexachlorobenzene has been detected 1n sediment samples taken from lakes throughout Germany Buchert et al.
In , the U. The aquatic sediments contained hexachloro- benzene at levels of ppb Blackwood and Spies, In a survey of nine Industrial plants see Table for site locations producing chloro- carbon compounds, L1 et al. Elder et al. Oliver and Nlchol studied the fate and distribution of chlorobenzenes 1n the Great Lakes and reported detecting all Isomers 1n the sediments of Lakes Superior, Huron, Erie and Ontario.
Human Tissue Residues. Studies of the transport, fate and bio- accumulation of the chlorinated benzenes reviewed above Indicate that human exposure 1s likely from air, food and drinking water Sections 5. In this section, human ambient exposure 1s confirmed by the reported levels of chlorobenzene 1n human adipose tissue, blood, breath and urine; unfortunately, the environmental concentrations were not available for comparison with the observed tissue concentrations.
The measured levels of several chlorobenzene Isomers In human adipose tissue are shown 1n Table Since human milk has a high fat content, chlorinated benzenes Ingested by pregnant and nursing mothers would be likely to distribute to this depot and, on repeated exposure, to bloaccumulate. Thus the suckling offspring would be susceptible to a high exposure via this Intake. Horlta et al. Barquet et al.
A study of another group of Australian mothers showed the opposite results: rural milk contained 0. In France, 18 of 49 breast milk samples contained hexachlorobenzene at concentrations of 0. Relatively low con- centrations of pentachlorobenzene and hexachlorobenzene 0. In another study, 50 milk samples from Helsinki women In Wlckstrom et al.
No detect- able hexachlorobenzene was found, however, 1n 57 samples of breast milk from women of rural Arkansas and Mississippi Strassman and Kutz, Levels 1n two Swedish women varied from 0. Courtney reviewed some of these and other studies that substantiate the ubiquity of hexachlorobenzene by the fact that people with no known exposure to the chlorobenzene had measurable tissue con- centrations. In a study Involving 28, people across the United States Murphy et al.
These findings were Interpreted as signifying non-occupational exposures. No actual levels were provided In this study. Astolfl et al. Ninety-seven rural and 97 urban children from Upper Bavaria all had detectable levels of hexa- chlorobenzene 1n their blood ranging from 2. An average concen- tration of 22 ppb hexachlorobenzene was measured 1n the blood of nonexposed Australians, whereas occupatlonally exposed people had an average concentra- tion of MorHa and Oh1 analyzed the blood of four male and two female residents of Tokyo for 1,4-d1chlorobenzene and reported an average of 9.
Wastes containing hexachlorobenzene were spread on a landfill 1n western Louisiana as a fly control measure Burns and Miller, Blood levels of hexachlorobenzene 1n 22 husband-wife pairs living near the landfill were analyzed. The average blood level for the men was 5. Forty-six Louisiana residents not living 1n the Immediate vicinity of the landfill had average blood levels of 0. The levels of chlorinated benzenes 1n the blood of nine residents of the Love Canal area In Niagara Falls, New York, were measured and are shown 1n Table Barkley et al.
Although the chlorobenzenes bloaccumulate 1n human adipose tissue and are detected In human blood, the levels are tempered by the elimination pro- cesses. The concentrations of chlorinated benzenes reported for human tissue see Table and blood, breath and urine see Tables and Indicate that humans absorb and store chlorinated benzenes. The bloaccumu- latlon of the chlorinated benzenes 1s offset by metabolism and elimination from the body. There are several limitations to this approach.
First, no comprehensive study of human exposure to the chlorobenzenes has been conducted; the available monitoring data Indicate the presence of the substances under the conditions of a given study and do not establish universal levels of exposure. Consequently, the studies that are cited and discussed 1n this section were selected on the basis of being the most likely to represent general population exposure.
Data on Instances of gross contamination; I. Second, no single study has analyzed any one medium for all of the chlorobenzenes. Hence, only data from a single study were used 1n the calculations for one type of exposure; aggregate or com- bined data were not used. Finally, quantitative data on the absorption of the various chlorobenzenes by humans through the lungs, skin or gastrointestinal tract 1s not available.
For this reason, the data 1n this section are estimates of yearly average ambient exposure levels I. The monitoring data used for the estimation of Inhalation exposure Table are taken from the overall mean concentration values given 1n Table In addition, this table presents estimates of the total yearly exposure of an adult man, adult woman, child and Infant using stan- dard respiratory volumes of 8.
The estimation of exposure of chlorobenzenes from drinking water requires that the mean or median concentrations of these compounds 1n finished water originating from a large number of both U. As discussed 1n Section 4. Therefore, a realistic assessment of the exposure of chlorobenzenes through the 1ngest1on of drinking water cannot be made at the present time.
However, the maximum concentrations of the chlorobenzenes found 1n U. Hexachlorobenzene 1s the only chlorinated benzene whose presence in food has been systematically Investigated. Based on data from the Total Diet Program, the FDA estimated the average dally Intake of hexachlorobenzene for fiscal year to be 0. This would result 1n a yearly exposure of 0. SUMMARY Annual production of chlorinated benzenes 1n 1s on the order of million pounds, the majority of which 1s accounted for by monochlorobenzene and dlchlorobenzenes.
Hexachloro- benzene 1s not currently produced as a commercial product 1n the United States IARC, , although 1t 1s a constituent of several Imported products and Is a byproduct or waste material 1n the production of many chemicals Mumnta and Lawless, These compounds are used 1n a number of organic chemical syntheses, Including the synthesis of other chloroben- zenes, and have applications as solvents, electrical equipment Insulators, pesticides, herbicides and fungicides.
Emissions of chlorobenzenes are most Hkely to occur during their manufacture or use as Intermediates and from the disposal of waste products from manufacturing operations. Hexachloro- benzene, for example, which 1s Imported but not produced commercially 1n the United States, occurs as a byproduct In the synthesis of nine other chloro- carbons; million pounds may be generated each year.
The most frequent- ly detected compounds 1n air and water were monochlorobenzene and the d1- and trlchlorobenzenes. Penta- and hexachlorobenzene are more frequently found 1n food and soil, although their detection may reflect more of the concern over their use as pesticides and fungicides, or their presence as contaminants 1n pesticides or fungicides, rather than the absence of the other ehlorobenzenes.
No comprehensive study of human exposure to the chlorobenzenes has been conducted, although their ubiquity 1n the environment and the detection of measurable residues In human tissue see Section 5. The contribution of the chlorobenzenes from all the three media air, water and food to a person's total exposure cannot be made with the limited environ- mental monitoring data.
The available data, however, Indicate that human Inhalation exposure to chlorobenzenes may be higher than Ingestlon exposure either through drinking water or through foods. Transport between the various environmental media 1s governed by the physical and chemical characteristics of the com- pounds and their Interaction with components of the environment.
Evapora- tion rates and solubilities Influence transport from water and soil Into air. Leaching rates, adsorption, rainfall, soil type and desorptlon affect the movement of chlorobenzenes from soil and sediment Into water and ground- water, as well as from water Into sediment and soil. The fate of chloroben- zenes 1n the environment depends on degradatlve processes, either abiotic degradation by chemical reactions or photolysis, or blotlc degradation by microbes, and on the rate at which these compounds are stored or accumulated by plants, animals and humans.
The transport and distribution of the chlorobenzenes 1n the atmosphere has not been Investigated. One study has suggested that distri- bution of one of the chlorobenzenes 1n air may be global. Atlas and Slam reported detecting hexachlorobenzene at a mean level of 0. These data led the authors to suggest that hexachlorobenzene 1s well mixed 1n the atmosphere and has wide distribution In the Northern Hemisphere.
A study of environmental contamination by hexa- chlorobenzene from Industrial plants L1 et al. The tendency of the hexachlorobenzene to remain 1n the atmosphere was not studied. Entry Into the atmosphere from other media 1s determined mainly by the substance's molecular weight, water solubility and vapor pressure.
Chloro- benzenes have vapor pressures ranging from 0. In general, these vapor pressures decrease with the Increase 1n the number of chlorine substltuents. Chlorobenzenes are likely to enter the atmosphere as a result of evaporation from soil and water and these types of studies are discussed 1n the following sections.
Chlorobenzenes have low solubility 1n water, with the solu- bility decreasing as the number of chlorine substltuents Increases, although some variation 1s evident among the Isomers Hawley, ; Sax, ; Weast, see Section 3. Once dissolved 1n water, despite their relatively low vapor pressures and high molecular weights, the chlorinated benzenes tend to evaporate quickly Mackay and Wolkoff, Two laboratory studies Indicate that evaporation of some of the Chlorobenzenes from an aqueous solution could be as rapid as a few minutes to a few days.
A 1-year field study of the transport of 1,4-dlchlorobenzene 1n Lake Zurich, Switzerland, also Indicated an Important role for evaporation 1n the removal of chlorobenzenes from water Schwarzenbach et a!. The authors found that the main Input of 1,4-d1chlorobenzene Into the lake was from wastewater treatment plants and that the half-life of the chemical was days. From a comparison of the seasonal variation 1n evaporation rates, they concluded that transport Into the atmosphere 1s the predominant Influence on the loss of 1,4-d1chlorobenzene from the lake.
In addition to laboratory and field Investigations, theoretical studies of the transport of chlorobenzenes In aquatic systems may be useful 1n predicting the distribution of these compounds and their removal from water by evaporation and sedimentation. Using Henry's Law Constant and various assumptions of water depth, air speed, etc. For chlorobenzene, 1,2-dlchlorobenzene and 1,2,4-tr1chlorobenzene, these values are 4. Falco et al. In their modeling, Falco et al. For comparative purposes, a summary of the authors' results for the lake or reservoir 1s presented 1n Table Chlorobenzenes have an Intermediate to high potential for adsorption onto soils, which tends to Increase with Increasing number of chlorine substltuents.
Once adsorbed, their movement within the soil 1s dependent on the soil type and the nature of the solvent or leachate. In the absence of a solvent, transport Into adjacent soil and the atmosphere 1s likely to result from vapor phase diffusion. Wilson et al.
These results Indicated that chlorinated benzenes are likely to leach Into groundwater and this mobility 1n groundwater was confirmed 1n a field study by Roberts et al. Studies on the transport of hexachlorobenzene Indicate a high potential for soil adsorption and for volatilization from porous soils.
Ausmus et al. One study has made estimates of residence times for various chloro- benzenes. Singh et al. The estimated-, residence times of these chemi- cals and dally percentage of each lost from the atmosphere are presented 1n Table The fate of chlorobenzenes 1n aquatic systems has not been completely characterized, although Initial studies Indicate that degradation of chlorobenzenes 1s possible by microblal communities 1n wastewater treat- ment plants and 1n natural bodies of water.
Other Investigations have Indi- cated that chlorobenzenes have a high potential for bloaccumulatlon and bio- concentration by aquatic species Section 5. Removal of chlorobenzenes by adsorption onto suspended material, which 1n turn settles and Is Incorpo- rated Into sediments, has not been demonstrated.
Lee and Ryan examined the degradation of various chlorinated com- pounds by microbes 1n samples of water and sediments taken from a river 1n Georgia. They observed that the degradation rates fit first-order expres- sions, although the degradation of the chlorinated compounds 1n water was slow.
In the sediment samples, monochlorobenzene was found to have a half-life of 75 days, which was longer than the chlorinated phenols, but more rapid than the degradation of hexachlorophene and DDE. In contrast, hexachlorobenzene showed no degradation by water or sediment microbes.
Davis et al. Both compounds were found to have high "ecological magnification" Indices and accumulated 1n both aquatic plants and animals. Both chemicals had low b1odegradab1! A number of other Investigators have studied the b1odegradabH1ty of chlorinated benzenes and these results are summarized 1n Table , In general, these results suggest that the b1odegradabH1ty decreases as the number of chlorine substltuents Increases, In addition to these laboratory studies, Zoeteman et al.
These half-lives are likely to be very Inaccurate since only a limited number of samples were taken. Roberts et al. No degradation was noted. From the slopes of the degradation curves, the authors estimated the half-lives of penta- and hexachlorobenzene to be and days, respectively.
Very little of the chemical disappeared from the cm-deep soil layer over the next 19 months. Isensee et al. Hexa- chlorobenzene was applied to samples of sterile and nonsterlle soil to create levels of 0. After storage of the samples under aerobic sterile and nonsterlle and anaerobic nonsterlle conditions for 1 year, analysis Indicated that none of the hexachlorobenzene had degraded 1n any sample. Studies with the d1- and trlchlorobenzenes have Indicated that these compounds are also persistent, but not to the degree reported for hexachlo- robenzene.
Ballschmlter and Scholz Investigated the metabolism of 1,2-, 1,3- and 1,4-d1chlorobenzene by a soil microbe of the Pseudomonas genera. In culture, the soil microbe was capable of degrading the compounds to dlchlorophenols and dlchloropyrocatechols. Similar cultures of Pseudo- monas also metabolized the tr1- and tetrachlorobenzenes to their respective chlorophenols.
In an experiment that more closely duplicated conditions 1n nature, Marlnucci and Bartha treated fresh field soil with radio- labeled 1,2,3- and 1,2,4-tr1chlorobenzene. They found very slow rates of degradation for these compounds, 0. The primary degradation products were chloro- phenols.
Haider et al. The growth performance parameters were calculated according to the following equations:. Live weight gain. Specific growth rate SGR. Water quality parameters were also analysed weekly following APHA For Statistical analysis all the data were subjected to one-way analysis of variance to determine significant differences between the treatments.
Courtship behaviour involves all the behavioural interaction between female and male which lead up before the fertilization. In the present study it was observed that courtship behaviour in goldfish started with the event of male chasing the female rapidly Figure. Male sometimes tried to attract the female by encircling the female in order to retain her in a given area.
Due to the encircling by the male female could not avoid the male and male touched the vent of the female Figure. These patterns of chasing and nudging touch and push females by the male was found to be in agreement with DeFraipont and Sorensen and Kobayashi et al During the present study courtship behaviour was recorded for different size categories ofmales i. Results showed that large sized males exhibitsthe highest frequency of chasing which was found to be Chasing, nipping and pushing frequencies followed similar trends, although the chasing frequency was significantlyhigher than the nipping and pushing frequency Figure 3.
However, for small sized males the frequency of chasing, nippingand pushing was lowest. Further in the goldfish for female mate choice association time was also taken as measurement and it was observed that female spent more time associating with large sized males followed by medium and least time in association with small sized males Table 3.
Table 3: Physicochemical parameters of aquarium water during the breeding experiments. Parameters Range 1 Temp. Male goldfish exhibited swimming movements in pairs, circling and pushing the female on the abdomen during courtship as observed during the present study was also reported in Danioaequipinnatus Vincent and Thomas and Puntiuschola Kharbuliet al , Turner Breeding performance of goldfish at variable sex ratio of male and female were studied.
Three different sex ratios taken in the present study were , and female: male. The highest seed per female was significantly high These results are supported by an earlier study carried out by Khalfalla et al The difference in fertilization percentage between the different sex ratios was significant. No significant differences were found in hatching percentage between sex ratio of and The reason for the highest seed production at sex ratio of 1female: 3 male may be the higher number of males per female leads to the complete expulsion of the ova from the ovary of the female and hence maximum fertilization.
Similar resultshave beenreported by earlier studies on the carps Kobayashi et al Jhaet al , Haniffaet al Incubation period ranged between hrs for all the treatments irrespective of various sex ratios. These results are in agreement with studies in goldfish by Kobayashi et al and Jhaet al Survival percentage of hatchlings remained unaffected by the different sex ratios.
The present research work further carried out the rearing aspect of goldfish using different types of feed. Study was conducted to investigate the effect of three different feed types on the growth performance and survival of goldfish larvae Initial weight of the goldfish larvae for all the three treatment ranged between 0.
In the present study feeding experiment was for 60 days and final growth parameters were measured after 60 days of initial stocking. The final weight, weight gain and specific growth rate were significantly affected by different types of feed, with the highest values obtained in fry fed mixed feed. Larvae fed with mixed feed were show significantly higher growth of 1. Survival was also significantly affected by feed. It was also higher in fish fed mixed feed and live feed than in those fed the pelleted feed.
Fry fed with pelleted feed had significantly lowest final weight 1. Specific growth rate was also highest in the group fed with mixed feed Figure 6. Mixed feed promoted the growth of goldfish larvae and the best growth performance of larvae of goldfish obtained through early rearing with mixed and live feed as observed in the present investigation.
It was found to be in agreement with the earlier studies on the goldfish conducted by the Kestemont and Krejszeff who achieved the best growth rate in intensively reared goldfish by feeding fish a mixed diet. Rottmannet al. Mixed schedules were superior to single high protein schedules because nitrogen retention was higher in the fish fed the mixed schedules. Results of the present work revealed that overall growth performance of the goldfish larvae higher in fish fed with mixed feed followed by the live feed and the pelleted feed.
These findings are in agreement with the earlier studies conducted on the Poeciliasphenops KumarguruVasagam , Kruger et al and Clariasgariepinus Olurin and Oluwo which obtained higher growth of the fish when fed with mixed diet. The present investigation further reported the suitability of live feed in comparison to pelleted feed. Live feed also produced high specific growth rate and growth, perhaps because large size, movement, and high protein content stimulated the predatory responses of the fish.
Live feed provide more protein than pelleted feed and all the amino acids essential to fish. Also, live zooplankton contains enzymes Bengtsonet al that help in initial digestion of juvenile fishes and apparently enhance their appetite, feed intake, and growth. Likewise, coho salmon Oncorhynchuskisutch fry fed on live feed grew faster than those fed pelleted feed.
The present findings were also supported by the study conducted by Degani in juvenile of Trichogastertrichopterus which reported that juveniles fed live feed grew faster than those fed formulated feed because of the palatability, high consumption and chemical composition of the live feed. Similarly a study by Chakarbartyet al. Swimming and feeding behaviour patterns were normal in all treatments irrespective of feed type. Water quality plays an important role in the survival of the fish and during the present work all the parameters as monitored on weekly interval were in optimum range Table 6.
The range of the water quality parameters recorded during the present work was in agreement with earlier studies on goldfish Kestomont , Krejszeff The global ornamental fish trade has been increasing and hence in recent years, research and development on breeding and seed production of ornamental fishes has also gained momentum. Despite the huge potential offered by the rich diversity and environment, export of ornamental fish from India continues to remain negligible.
Development of this sector requires strategies involving sustainable exploitation of the existing natural resources and breeding of native and exotic varieties under controlled conditions. Presently the industry is not organised and the earning potential of the sector is not being exploited in a technology driven manner in harmony with nature. With concerted efforts towards ornamental fish breeding and culture it may be possible to put India on the world map of ornamental fish trade.
Ornamental fish seed production provides additional income to the fish farmers and help in their socioeconomic development. If the work of ornamental fish breeding and rearing in aquaria and garden pools is adopted along with some allied activities live feed production, artificial feed production and equipments business it can be a boon for the thousands of unemployed youths and women.
Women can run small home units of ornamental fish breeding or rearing or both as it can be practiced in rural areas as well as in urban areas with little alteration of backyard or even the roof of a dwelling. Women can improve their family economy and nutrition and thereby their improved position in the family owing to their contribution to the family economy. At the first stage of starting of an ornamental fish breeding unit very sophisticated or complicated equipment is not necessary.
Ornamental fish farming can be a promising alternative for many people and it has the potential to contribute to the economic growth of states concerned and the sustainable development of aquatic resources. Ornamental fish breeding can be done successfully with high yield at low cost.
Different capital cost, variable cost and profit obtained from the unit of ornamental fish breeding in a year is given below. Fixed capital. Low cost shed of sq. Bore-well with 1 hp pump Oxygen cylinder with accessories Aerators Nets, mugs, buckets etc. Cost for 1 year Variable cost. Cost of fish brooders 15, Cost of feed, manures, chemicals 10, Maintenance charges 5, Miscellaneous charges 2, Sub- total Sale of nos ornamental fish Rs.
Net Profit Ahilan B, Nithiyapriyatharshini A and Ravaneshwaran K Influence of certain herbal additives on the growth, survival and disease resistance of goldfish, Carassiusauratus linnaeus. Tamilnadu Journal of Veterinary and Animal Sciences 6 1 : New York.
In: R. Broune, P. Sorgeloos, C. Trotman ed. Artemia Biology. Advances in Environmental biology. Aquaculture, DeFraipont M and Sorensen P W Exposure to the pheromone 17a,20b-dihydroxypregnenone enhances the behavioural spawning success, sperm production and sperm motility of male goldfish. Animal Behaviour, 46, Aquaculture Abbassa International Journal for Aquaculture, 1 A Taiwania 52 1 Abbassa International Journal for Aquaculture, 1 B Fish Farmer 3. James R and Sampath K Effect of feed type on growth and fertility in ornamental fish, Xiphophorushelleri.
The israeli journal of aquaculture. Bamidgeh 56 4. Kestomont P Influence of feed supply, temperature and body size on the growth of goldfish, Carassiusauratus larvae. Volume Issue Khalfalla M. M, Hammouda Y. Inland Fish. India, 36, 58— Fish Physiology and Biochemistry, 26, Electronic Journal of Polish Agricultural Universities. Aquarium Science and Conservation 3: Kumaraguruvasagam K P, Shanmugam A, Rajagopalan S Dietary effect on fry production and growth performance of sailfin molly, Poecilialatipinna , in salt water.
ActaIchthyologiaEtPiscatoria 37 1 : Larvae fed decapsulatedArtemia, live daphnia, or commercial starter diet. The Israeli journal of Aquaculture- Bamidgeh. Aquaculture, volume 71— Stacey N Hormones, pheromones and reproductive behaviour. Fish Physiology and Biochemistry, — Thesis, University of Kafr El-sheikh, Egypt. Thakur N K Ornamental fishes — Getting to know them. In: Training Manual on Advance in keeping and breeding ornamental fishes.
Chlorine is a chemical sanitizer that typically comes in either tablet, powder or liquid form, which is then prepped and added to your swimming pool in order to keep your pool water clean and safe to swim. Combined chlorine is also known as chloramine. And not to worry, the doses of hydrochloric acid being described here are far less harmful to us humans, and certainly less harmful than letting those microscopic nasties live and breed freely in your pool.
I already mentioned that chlorine used in swimming pools comes in either tablet, powder or liquid form, but there are some nuances you should be aware of before pulling the trigger on a purchase. Each form has benefits and drawbacks, as well as different price-points, applications and overall effectiveness in specific situations. Chlorine tablets are typically used with a dispenser that allows them to be released into your pool consistently over time.
This makes it the easiest form of chlorine to use, and the one we recommend to most domestic pool owners. Tablets can also contain other helpful substances such as algaecide and water clarifier, removing the need to purchase and add these independently. This is a more hands on approach, but it also gives you more granular pun intended control over your chlorine levels.
Liquid chlorine is typically the cheapest option and is poured directly into the pool, but with pH level of around 13 it does require careful balancing of your pool water which can increase costs. This is a popular option for larger, commercial pools because it can be quickly added in large quantities.
Whether you choose to go with tablet, powdered or liquid chlorine, know that these come in either unstabilized and stabilized variants. Since not all swimming pools are outdoors or exposed to the sun, unstabilized chlorine can be used to the same effect in the right circumstances.
Finally, since this type of chlorine has a shorter lifespan than stabalized chlorine, it can also be used in large doses to shock your pool, or even as an emergency top up to quickly restore falling chlorine levels. To further complicate things, there are 3 different chlorine compounds you can buy that fall into the unstabilized category:.
Again, the added acid is only important for swimming pools that are frequently exposed to the sun, and having it mixed in with your chlorine just makes your life easier when it comes to dosages. This time there are only 2 different chlorine compounds you can buy that fall into the stabilized category:. How to properly add chlorine to a pool is a common question from new pool owners, and you may find conflicting advice on the best way to approach it.
A floating chlorine dispenser is a little container for chlorine pucks that floats around the surface of your pool, slowly dissolving and releasing the chlorine into the water. These things also tend to get stuck behind pool ladders or steps, at which point the chlorine being released starts to build up in one area of the pool. In fact, this high concentration near the edges can bleach your pool liners. Your filter system is designed to pull in, clean and circulate your pool water.
Of course, an integral part of that system is your skimmer, and the skimmer can be leveraged when it comes to adding chlorine to your pool. All you need to do is add chlorine to your pool skimmer preferably tablets , and you can sit back and let it do the work of sending the dissolved chlorine through your filter system and our into your pool water.
An automatic chlorinator attaches to your filter system and administers a measured amount chlorine to your pool constantly, on autopilot. All you need to do is keep it topped up with chlorine again, preferably tablets and it will output as much chlorine as you tell it to via the dial. This setup will also allow you to pump large burst of chlorine into your water, or simply regulate it over time. Remember when I told you chlorine combines with the harmful stuff in your pool to create new compounds called chloramines?
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Chlorine disinfectants have been widely used in the poultry supply usage during animal breeding has led to a marked increase in the. Chlorine is the main chemical disinfectant used in drinking water treatment, i.e. intensive farming and intensive cattle breeding (Baert. In this study, the effect of chemical sterilization by inclusion of chlorine dioxide (ClO2) in the culture medium on the in vitro.