Ambient Water Quality Guidelines for Chlorophenols

Water Quality

Ambient Water Quality Guidelines for Chlorophenols

First Update

P. D. WARRINGTON Ph. D.

Water Quality Branch
Water Management Division

November 1996

Acknowledgements

Special thanks are extended to Mr. John Wilkinson (the Pentachlorophenol Task Force, Washington, DC), Dr. Dan Woltering (the ENVIRON Corporation, Arlington, Virginia) and Dr. Bruce Bernard (SRA International, Inc., Washington, DC) for a thorough review of the first version of this document. They made numerous comments, suggested a revised protocol, brought further literature citations to our attention and supplied unpublished data, which increased the timeliness and accuracy of the document.

Abstract

This report is one of a series which establishes ambient water quality guidelines for British Columbia. The guidelines represent safe conditions or levels of a variable which have province-wide application and are set to protect various water uses. This report sets guidelines for the chlorophenols, chlorinated monocyclic aromatic hydrocarbons, to protect drinking water, fresh-water and marine aquatic life, recreational waters, food processing industries and wildlife and livestock drinking water. Guidelines were not set for crop irrigation or other industries due to the lack of suitable data on the effects of chlorophenols for these uses. Each chapter where guidelines are proposed has a rationale section immediately following the proposed guidelines. The guidelines are summarized in three tables, 1.1.1, 1.1.2 and 1.1.3, at the back of this report. CCREM (CCME) has not set guidelines for all the water uses and all the chlorophenols for which we have set guidelines.

A major use of the guidelines is to set ambient water quality objectives. These objectives are the guidelines, adopted or modified to meet specific local conditions, applied to a particular body of water to protect the most sensitive designated water use. The guidelines and objectives do not have legal standing, but are used in the preparation of Waste Management Permits, Orders or Approvals, which do have legal standing.

No data were found on the effects of chlorophenols on industrial processes. In the manufacture of some industrial products such as photographic chemicals, paints, oils, textiles, glues, starches, cellulosic wood fillers, rubber, protein-based products and shampoos, and in industrial cooling and process waters in mills, chlorophenols are deliberately added to prevent growth of microorganisms. The only place where chlorophenols would be a problem is in water actually incorporated into a food product, or used to wash and process food products. Here, due to taste and odor problems, water of drinking quality is required and the Drinking Water Guidelines are recommended. There are virtually no data on the effects of chlorophenols in irrigation water and no guidelines are set. There is a short section in Chapter 7.2 discussing effects of chlorophenols on seed germination and cytotoxicity in plants.

Only 8 of the 19 chlorophenols are in commercial use; the rest are produced incidentally when organic material is chlorinated. For most organisms there are generally abundant data on the effects of PCP, pentachlorophenol, but few on the effects of other congeners, therefore the ratios of the toxicities of each chlorophenol to PCP, as determined in several experiments, were applied to the best PCP data to determine guidelines for the other congeners. Chlorophenols are notorious for causing taste and odor problems in water at levels below those which are toxic. The half-life of most chlorophenols in nature is short, rarely as long as a month. Once input to the environment stops, levels will drop rapidly; bacterial breakdown of chlorophenols occurs quite readily.

Chlorophenols were used world-wide as broad spectrum biocides; residues and breakdown products were ubiquitous in air, water, sediment, and organisms. Their major use, particularly PCP and TTCPs, has been as an anti-sapstain fungicide in the cut lumber industry, but this use no longer occurs in North America. PCP is now used only to pressure and thermal treat heavy timbers and poles for outdoor construction. Chlorophenols are also used as antiseptics and organic feedstocks for pesticide manufacture; many commercial products contain chlorophenols, notably packaging materials in which they are used as preservatives. The chlorophenols were generally made by chlorinating phenols and by hydrolysis of chlorobenzenes; dioxins were common byproducts of their manufacture, especially in high temperature hydrolysis processes. This dioxin contamination sometimes made it difficult to decide whether an observed effect was due to the dioxin contaminant or to the chlorophenol. Presently PCP used in North America is made by chlorinating phenol under controlled conditions which preclude the production of measurable 2,3,7,8-TCDD in the current product.

The chlorination of wastewater with high organic loads, such as sewage, leads to low levels of chlorophenol production, but this practice is widespread. Major sources of chlorophenol input to the environment included wood treatment facilities and pulp and paper mills. Fly ash from incinerators, power stations, fireplaces, and slash and forest fires also contribute to the widespread distribution of chlorophenols in the environment.

Once released to the environment physical, chemical and biological processes break down chlorophenols, ultimately to carbon dioxide, water and chloride. The half-lives of the chlorophenols range from hours to months, depending upon the isomer and the conditions. Photodegradation is only important in shallow water under high irradiation levels; hydrolysis and oxidation are relatively unimportant in natural chlorophenol degradation; evaporation and volatilization are only important in shallow water subject to vigorous mixing; adsorption is a major process and most chlorophenols introduced into the environment will eventually be found adsorbed to organic sediments.

Effluents and spills from wood treatment facilities and pulp and paper mills were responsible for a number of fish kills. Fish, immersed in their uptake medium, bioconcentrate chlorophenols up to 1000 times, for whole body loads, in spite of very efficient conjugation and elimination processes. The half-life of chlorophenols in fish is less than 1 day, thus the existence of high levels in fish tissues is indicative of chronic, on-going or current exposure. There is an initial lag period while the metabolic processes of the fish adapt to conjugating and excreting chlorophenols; once adapted, the depuration half-lives are short, generally less than 24 hours.

Chlorophenols affect the common mitochondrial respiration and energy storage processes in all higher plants and animals . The effect is to waste the energy stored in food which is thus not available for growth and maintenance, even though respiration rates rise. This terminal respiration process is essential and universal; results observed in one species are applicable to others, and death will result if it is prevented or severely disrupted. Toxicity levels in different organisms are not identical because of the relative efficiencies of uptake, transport, and elimination of chlorophenols by different organisms. Chlorophenols are immunotoxic, fetotoxic, and embryotoxic, but not neurotoxic or teratogenic. Mutagenicity and carcinogenicity assays on chlorophenols, even at the very high doses used in some tests, have not given definitive answers.

Toxicity to aquatic life, and the generation of an unpleasant taste in fish and shellfish living in chlorophenol contaminated waters, are the effects which are manifested at the lowest chlorophenol concentrations; these effects occur in the sub-µg/L concentration range. In mammals, chlorophenols are not accumulated to high levels in fat due to very rapid excretion as glucuronide conjugates, thus keeping bioconcentration factors low. In almost all mammals the dose of PCP needed to kill one half of the test animals is fairly uniform at about 150 µg/g of body weight.

Microorganisms can adapt their metabolic processes to use virtually any source of carbon, including chlorophenols, for growth. The evidence for fungal and bacterial degradation of chlorophenols in nature is widespread. If the organisms have never been exposed to chlorinated organics, there will be an initial adaptation period of several weeks to a month. Once the adaptive phase is over and a large microbial population has been established, breakdown of the chlorophenols is rapid; subsequent additions of chlorophenols to the environment are quickly degraded, if the concentrations are not excessive. Chlorophenols with chlorines in the ortho or para positions (2, 4 and 6) are less toxic and more readily degraded than those with chlorines in the meta (3 and 5) positions.

Recommended Water Quality Guidelines

HUMAN DRINKING WATER

We recommend adoption of the existing Canadian Drinking Water Quality Guidelines for Chlorophenols, which have been adopted by the BC Ministry of Health, with the addition of a monochlorophenol guideline of 0.1 µg/L. The existing Canadian Guidelines specify certain specific isomers and omit any mention of others. We have set aesthetic guidelines based on the total concentration of all the isomers for each group of chlorophenols; the toxicity guidelines are specific for certain congeners in each isomer group.

Aesthetic Guidelines (taste and odour)

In raw human drinking water chlorophenols should not exceed the following:

0.1 µg/L monochlorophenols (MCPs)
0.3 µg/L dichlorophenols (DCPs)
2 µg/L trichlorophenols (TCPs)
1 µg/L tetrachlorophenols (TTCPs)
30 µg/L pentachlorophenol (PCP)

Toxicity Guidelines

In raw human drinking water chlorophenols should not exceed the following:

900 µg/L 2,4-dichlorophenol
5 µg/L 2,4,6-trichlorophenol
100 µg/L 2,3,4,6-tetrachlorophenol
60 µg/L pentachlorophenol

LIVESTOCK AND WILDLIFE

Aesthetic Guidelines

The recommended guidelines based on organoleptic effects are the same as the human drinking water aesthetic guidelines.

Toxicity Guidelines

The following guidelines, based on toxicity calculations, are recommended. While not toxic they may prove unpalatable to some species and thus restrict water intake or force animals to search for alternate sources of drinking water. These toxicity based guidelines may be appropriate under some conditions but generally the human drinking water guidelines are recommended. These values assume no other source of chlorophenols in the diet or in the inhaled air.
In livestock and wildlife drinking water, chlorophenols should not exceed the following levels:

For lactating animals under high temperatures and high water intake rates of up to 200mL/kg:

185 mg/L monochlorophenols (MCPs)
46 mg/L dichlorophenols (DCPs)
21 mg/L trichlorophenols (TCPs)
41 mg/L tetrachlorophenols (TTCPs)
17.5 mg/L pentachlorophenol (PCP)

For non-lactating animals under normal temperatures and water intake rates of 20 ml/kg:

1854 mg/L monochlorophenols (MCPs)
460 mg/L dichlorophenols (DCPs)
210 mg/L trichlorophenols (TCPs)
410 mg/L tetrachlorophenols (TTCPs)
175 mg/L pentachlorophenol (PCP)

AQUATIC LIFE

Flavour Impairment Guidelines

The recommended guidelines for the prevention of flavor impairment in fish muscle are given in Tables 1.1.1 and 1.1.3. No published taste thresholds for crustacean or mollusc meat were found for the chlorophenols. Table 1.1.1 gives chlorophenol levels in water which, if met, should result in fish muscle tissue remaining within acceptable limits. Table 1.1.3 gives the maximum acceptable levels for chlorophenols in fish muscle tissue. If these levels were applied to fat tissue or whole body, a much lower water guideline would be necessary since the levels of chlorophenols in fat and liver are much higher than in muscle. These guidelines are only for flavor impairment to human consumers. Consideration was given to other animal consumers, with lower taste thresholds than humans, that might be affected by tainted fish. Expected effects would include a loss of desire to eat their only or preferred food source due to flavor impairment or to flavor impairment of the milk in lactating females which might prevent the young from nursing. Except for monochlorophenols and dichlorophenols, the recommended guidelines for aquatic life are low enough to protect such animals unless their taste sensitivity is better than that of humans. No data were available to warrant further adjustment of the guidelines. Food preference trials with predators of fish, and other aquatic prey organisms, are required to justify any lower guidelines.


	Water Quality Ambient Water Quality Guidelines for Chlorophenols First Update P. D. WARRINGTON Ph. D. Water Quality Branch Water Management Division November 1996 *Acknowledgements* Special thanks are extended to Mr. John Wilkinson (the Pentachlorophenol Task Force, Washington, DC), Dr. Dan Woltering (the ENVIRON Corporation, Arlington, Virginia) and Dr. Bruce Bernard (SRA International, Inc., Washington, DC) for a thorough review of the first version of this document. They made numerous comments, suggested a revised protocol, brought further literature citations to our attention and supplied unpublished data, which increased the timeliness and accuracy of the document. Abstract This report is one of a series which establishes ambient water quality guidelines for British Columbia. The guidelines represent safe conditions or levels of a variable which have province-wide application and are set to protect various water uses. This report sets guidelines for the chlorophenols, chlorinated monocyclic aromatic hydrocarbons, to protect drinking water, fresh-water and marine aquatic life, recreational waters, food processing industries and wildlife and livestock drinking water. Guidelines were not set for crop irrigation or other industries due to the lack of suitable data on the effects of chlorophenols for these uses. Each chapter where guidelines are proposed has a rationale section immediately following the proposed guidelines. The guidelines are summarized in three tables, 1.1.1, 1.1.2 and 1.1.3, at the back of this report. CCREM (CCME) has not set guidelines for all the water uses and all the chlorophenols for which we have set guidelines. A major use of the guidelines is to set ambient water quality objectives. These objectives are the guidelines, adopted or modified to meet specific local conditions, applied to a particular body of water to protect the most sensitive designated water use. The guidelines and objectives do not have legal standing, but are used in the preparation of Waste Management Permits, Orders or Approvals, which do have legal standing. No data were found on the effects of chlorophenols on industrial processes. In the manufacture of some industrial products such as photographic chemicals, paints, oils, textiles, glues, starches, cellulosic wood fillers, rubber, protein-based products and shampoos, and in industrial cooling and process waters in mills, chlorophenols are deliberately added to prevent growth of microorganisms. The only place where chlorophenols would be a problem is in water actually incorporated into a food product, or used to wash and process food products. Here, due to taste and odor problems, water of drinking quality is required and the Drinking Water Guidelines are recommended. There are virtually no data on the effects of chlorophenols in irrigation water and no guidelines are set. There is a short section in Chapter 7.2 discussing effects of chlorophenols on seed germination and cytotoxicity in plants. Only 8 of the 19 chlorophenols are in commercial use; the rest are produced incidentally when organic material is chlorinated. For most organisms there are generally abundant data on the effects of PCP, pentachlorophenol, but few on the effects of other congeners, therefore the ratios of the toxicities of each chlorophenol to PCP, as determined in several experiments, were applied to the best PCP data to determine guidelines for the other congeners. Chlorophenols are notorious for causing taste and odor problems in water at levels below those which are toxic. The half-life of most chlorophenols in nature is short, rarely as long as a month. Once input to the environment stops, levels will drop rapidly; bacterial breakdown of chlorophenols occurs quite readily. Chlorophenols were used world-wide as broad spectrum biocides; residues and breakdown products were ubiquitous in air, water, sediment, and organisms. Their major use, particularly PCP and TTCPs, has been as an anti-sapstain fungicide in the cut lumber industry, but this use no longer occurs in North America. PCP is now used only to pressure and thermal treat heavy timbers and poles for outdoor construction. Chlorophenols are also used as antiseptics and organic feedstocks for pesticide manufacture; many commercial products contain chlorophenols, notably packaging materials in which they are used as preservatives. The chlorophenols were generally made by chlorinating phenols and by hydrolysis of chlorobenzenes; dioxins were common byproducts of their manufacture, especially in high temperature hydrolysis processes. This dioxin contamination sometimes made it difficult to decide whether an observed effect was due to the dioxin contaminant or to the chlorophenol. Presently PCP used in North America is made by chlorinating phenol under controlled conditions which preclude the production of measurable 2,3,7,8-TCDD in the current product. The chlorination of wastewater with high organic loads, such as sewage, leads to low levels of chlorophenol production, but this practice is widespread. Major sources of chlorophenol input to the environment included wood treatment facilities and pulp and paper mills. Fly ash from incinerators, power stations, fireplaces, and slash and forest fires also contribute to the widespread distribution of chlorophenols in the environment. Once released to the environment physical, chemical and biological processes break down chlorophenols, ultimately to carbon dioxide, water and chloride. The half-lives of the chlorophenols range from hours to months, depending upon the isomer and the conditions. Photodegradation is only important in shallow water under high irradiation levels; hydrolysis and oxidation are relatively unimportant in natural chlorophenol degradation; evaporation and volatilization are only important in shallow water subject to vigorous mixing; adsorption is a major process and most chlorophenols introduced into the environment will eventually be found adsorbed to organic sediments. Effluents and spills from wood treatment facilities and pulp and paper mills were responsible for a number of fish kills. Fish, immersed in their uptake medium, bioconcentrate chlorophenols up to 1000 times, for whole body loads, in spite of very efficient conjugation and elimination processes. The half-life of chlorophenols in fish is less than 1 day, thus the existence of high levels in fish tissues is indicative of chronic, on-going or current exposure. There is an initial lag period while the metabolic processes of the fish adapt to conjugating and excreting chlorophenols; once adapted, the depuration half-lives are short, generally less than 24 hours. Chlorophenols affect the common mitochondrial respiration and energy storage processes in all higher plants and animals . The effect is to waste the energy stored in food which is thus not available for growth and maintenance, even though respiration rates rise. This terminal respiration process is essential and universal; results observed in one species are applicable to others, and death will result if it is prevented or severely disrupted. Toxicity levels in different organisms are not identical because of the relative efficiencies of uptake, transport, and elimination of chlorophenols by different organisms. Chlorophenols are immunotoxic, fetotoxic, and embryotoxic, but not neurotoxic or teratogenic. Mutagenicity and carcinogenicity assays on chlorophenols, even at the very high doses used in some tests, have not given definitive answers. Toxicity to aquatic life, and the generation of an unpleasant taste in fish and shellfish living in chlorophenol contaminated waters, are the effects which are manifested at the lowest chlorophenol concentrations; these effects occur in the sub-µg/L concentration range. In mammals, chlorophenols are not accumulated to high levels in fat due to very rapid excretion as glucuronide conjugates, thus keeping bioconcentration factors low. In almost all mammals the dose of PCP needed to kill one half of the test animals is fairly uniform at about 150 µg/g of body weight. Microorganisms can adapt their metabolic processes to use virtually any source of carbon, including chlorophenols, for growth. The evidence for fungal and bacterial degradation of chlorophenols in nature is widespread. If the organisms have never been exposed to chlorinated organics, there will be an initial adaptation period of several weeks to a month. Once the adaptive phase is over and a large microbial population has been established, breakdown of the chlorophenols is rapid; subsequent additions of chlorophenols to the environment are quickly degraded, if the concentrations are not excessive. Chlorophenols with chlorines in the ortho or para positions (2, 4 and 6) are less toxic and more readily degraded than those with chlorines in the meta (3 and 5) positions. Recommended Water Quality Guidelines HUMAN DRINKING WATER We recommend adoption of the existing Canadian Drinking Water Quality Guidelines for Chlorophenols, which have been adopted by the BC Ministry of Health, with the addition of a monochlorophenol guideline of 0.1 µg/L. The existing Canadian Guidelines specify certain specific isomers and omit any mention of others. We have set aesthetic guidelines based on the total concentration of all the isomers for each group of chlorophenols; the toxicity guidelines are specific for certain congeners in each isomer group. Aesthetic Guidelines (taste and odour) In raw human drinking water chlorophenols should not exceed the following: 0.1 µg/L monochlorophenols (MCPs) 0.3 µg/L dichlorophenols (DCPs) 2 µg/L trichlorophenols (TCPs) 1 µg/L tetrachlorophenols (TTCPs) 30 µg/L pentachlorophenol (PCP) Toxicity Guidelines In raw human drinking water chlorophenols should not exceed the following: 900 µg/L 2,4-dichlorophenol 5 µg/L 2,4,6-trichlorophenol 100 µg/L 2,3,4,6-tetrachlorophenol 60 µg/L pentachlorophenol LIVESTOCK AND WILDLIFE Aesthetic Guidelines The recommended guidelines based on organoleptic effects are the same as the human drinking water aesthetic guidelines. Toxicity Guidelines The following guidelines, based on toxicity calculations, are recommended. While not toxic they may prove unpalatable to some species and thus restrict water intake or force animals to search for alternate sources of drinking water. These toxicity based guidelines may be appropriate under some conditions but generally the human drinking water guidelines are recommended. These values assume no other source of chlorophenols in the diet or in the inhaled air. In livestock and wildlife drinking water, chlorophenols should not exceed the following levels: For lactating animals under high temperatures and high water intake rates of up to 200mL/kg: 185 mg/L monochlorophenols (MCPs) 46 mg/L dichlorophenols (DCPs) 21 mg/L trichlorophenols (TCPs) 41 mg/L tetrachlorophenols (TTCPs) 17.5 mg/L pentachlorophenol (PCP) For non-lactating animals under normal temperatures and water intake rates of 20 ml/kg: 1854 mg/L monochlorophenols (MCPs) 460 mg/L dichlorophenols (DCPs) 210 mg/L trichlorophenols (TCPs) 410 mg/L tetrachlorophenols (TTCPs) 175 mg/L pentachlorophenol (PCP) AQUATIC LIFE Flavour Impairment Guidelines The recommended guidelines for the prevention of flavor impairment in fish muscle are given in Tables 1.1.1 and 1.1.3. No published taste thresholds for crustacean or mollusc meat were found for the chlorophenols. Table 1.1.1 gives chlorophenol levels in water which, if met, should result in fish muscle tissue remaining within acceptable limits. Table 1.1.3 gives the maximum acceptable levels for chlorophenols in fish muscle tissue. If these levels were applied to fat tissue or whole body, a much lower water guideline would be necessary since the levels of chlorophenols in fat and liver are much higher than in muscle. These guidelines are only for flavor impairment to human consumers. Consideration was given to other animal consumers, with lower taste thresholds than humans, that might be affected by tainted fish. Expected effects would include a loss of desire to eat their only or preferred food source due to flavor impairment or to flavor impairment of the milk in lactating females which might prevent the young from nursing. Except for monochlorophenols and dichlorophenols, the recommended guidelines for aquatic life are low enough to protect such animals unless their taste sensitivity is better than that of humans. No data were available to warrant further adjustment of the guidelines. Food preference trials with predators of fish, and other aquatic prey organisms, are required to justify any lower guidelines.