|
||||||
|
||||||
|
|
|
|||
|
Water Quality Ambient Water Quality Guidelines for Chlorophenols 3. DISSEMINATION OF THE CHLOROPHENOLS 3.1 Uses of Chlorophenols Chlorophenols as a group were used as broad-spectrum biocides world-wide; residues and breakdown products are almost ubiquitous in the environment. Specific uses are as herbicides, pesticides, fungicides, algicides, insecticides, bactericides, molluscicides and slimicides. They were used by the domestic, agricultural, and industrial sectors of society (8, 30, 48, 161, 164, 199, 202, 222, 223, 225, 254, 256, 258, 268, 270, 289). Chlorophenols were used as slimicides in pulp and paper manufacturing (202, 222), and in cooling towers (289); they were also used as general biocides in paints, oils, leather, textiles, cellulose and starch compounds, adhesives, proteins, rubbers, rug shampoos, photographic processing chemicals, and food processing (48, 202, 289). The major use of penta- and tetrachlorophenols has been as a wood preservative and anti-sapstain fungicide. Fungi cause staining in the sapwood which reduces wood quality and market price; such attacks may also promote attacks by other organisms which cause structural damage to timbers (33, 48, 202, 222, 254, 256, 258, 268, 289). In dark, warm, humid conditions, like the holds of ships, such fungi can grow rapidly (268). Chlorophenols were used primarily for preservation of freshly cut dimension lumber, but they are now used primarily for other kinds of wood preservation such as fence posts, telephone poles, railroad ties, pilings, and timbers used for bridges and in mines. The useful life of such treated timbers is greatly extended, which saves money in replacement costs and also reduces the need for such wood products. In addition, smaller timbers can be used, since there is no longer a need to make allowance for reduced strength, caused by structural damage, by using oversized timbers. The useful life of treated wood timbers can be extended 5 to 15 fold and timber needs reduced three to six fold over untreated wood. The life-span of untreated wood is quite short: 2 years for mine timbers due to moisture and high temperatures, 5 years for railway ties due to chewing insects, and 1 year for marine pilings due to borers (256). For wood preservation, PCP is preferred but some TTCPs are also used as active ingredients. The less substituted chlorophenols are less desirable due to their higher odors, greater solubilities in water, greater volatility and potential for skin irritation. Some specific uses of the chlorophenol congeners are given below; data were not available for all of the congeners. MCP Monochlorophenols have been used as antiseptics for 100 years (397). 2-MCP This compound is used as an intermediate feedstock in the manufacture of higher chlorophenols and chlorocresols used as biocides. It is also used to form intermediates in the production of phenolic resins and to extract sulphur and nitrogen compounds from coal (372). 3-MCP This chlorophenol is also used to extract sulphur and nitrogen compounds from coal (364) and as an intermediate in organic synthesis of other chlorophenols and phenolic resins (442, 445). 4-MCP The most common monochlorophenol, 4-MCP, is used to extract sulphur and nitrogen compounds from coal (372). It is an intermediate in the synthesis of dyes and drugs, a denaturant in alcohol, a solvent in the refining of mineral oils, and is used in the production of the herbicide 2,4,-D, the germicide 4-chlorophenol-o-cresol and the chlorophenol 2,4-DCP (372, 442, 445). 2,4-DCP The herbicide, 2,4-D, and the chlorophenol, PCP, are made from 2,4-DCP. Alkali salts of 2,4-DCP are used as germicides and antiseptics, to manufacture the miticide 2,4-dichlorophenol benzene sulfonate, to make the seed disinfectant, antiseptic and moth repellent, 2,2'-dihydroxy-3,5,3',5'- tetrachlorodiphenylmethane and as an intermediate to make soil sterilants, plant growth regulators and wood preservatives (8, 315, 495). 2,4,5-TCP This isomer is used to manufacture hexachlorophene, a disinfectant and sanitation product for domestic, hospital, and veterinary use. The main uses of 2,4,5-TCP are as fungicides and bactericides on swimming pool related surfaces, household sickroom equipment, food processing plants and equipment, food contact surfaces, hospital rooms, and bathrooms. It is used in the textile industry and as a raw material to manufacture the industrial and agricultural chemicals 2,4,5-T, Silvex, Ronnel, Erbon, and Sodium 2,4,5-Trichlorophenate (445, 464, 480) . 2,4,6-TCP The sodium and potassium salts of 2,4,6-TCP are used for wood preservation (222, 225) and as antiseptics, fungicides and bactericides. They are used as preservatives in glue, for wood preservation, as anti-mildew agents in textiles, as germicides, and as defoliant herbicides (232, 445, 464). 2,3,4,5-TTCP This tetrachlorophenol is used as a fungicide and wood preservative (442, 445) in wood processing plants such as sawmills and plywood plants, wood protection and preservation plants, kraft pulp mills, sewage treatment plants, and pesticide manufacturing and formulating plants (321). 2,3,4,6-TTCP This tetrachlorophenol is used as an insecticide and wood preservative (442, 222, 225); for the latter use it is usually as the sodium or potassium salt. The major use is as a fungicide in wood preservation (442, 445) in sawmills, plywood plants, wood protection and preservation plants, kraft pulp mills, sewage treatment plants, and pesticide manufacturing and formulating plants (321). Commercial PCP usually contains 3% to 10% 2,3,4,6-TTCP as an active ingredient for wood preservation. 2,3,5,6-TTCP This tetrachlorophenol is used as a fungicide and wood preservative (442, 445) and in wood processing plants such as sawmills, plywood plants, kraft pulp mills, and wood protection and preservation plants. It is also used in pesticide manufacturing and formulating operations (321). PCP Petrochemical drilling fluids contain polysaccharides, starch and XC polymer; Na-PCP was used, in concentrations around 700 to 1400 mg/L, to prevent bacterial fermentation of these fluids (202, 640). About 75% of the PCP used was applied as a wood preservative for poles, pilings and cross-arms. About 15% of the PCP was used as the sodium salt, Na-PCP, in the leather, paper, fibreboard, photography, paint, construction and textile industries and as a molluscicide. It was usually used at a 1 to 10% concentration as an aqueous solution for these purposes. It was also used for slime control in adhesives, proteins, oils, leathers, paints and rubber (538). In marine situations 1 mg/L of Na-PCP prevents fouling of pipes and conduits (164). PCP was the main chlorophenol used as a slimicide in pulp and paper manufacturing (202, 222) and in cooling towers (289). It is also used as an intermediate in the manufacture of the pesticide 2,4-D and other chemicals (289). PCP is the major chlorophenol used in wood preservation and anti-sapstain treatment where it is often used as the sodium or potassium salt, Na-PCP or K-PCP. It is also used as an insecticide against termites, wood borers, and powder-post beetles (48, 202). In agriculture, PCP was used as a pre- and post-planting herbicide, especially against grasses in rice paddies (48, 223), and as a general purpose fungicide (223). PCP controls weeds that 2,4-D does not, and is cheaper. It has therefore supplanted 2,4-D in South-East Asia, resulting in extensive fish and shellfish kills (223). In North America the only currently registered uses for PCP are for pressure and thermal treating of railway ties, utility poles, pilings and outdoor construction materials. All other uses have been stopped.
Table A3-1 in Jones (91) gives an extensive list of over 100 commercial products containing chlorophenols, which were registered under the Canadian Federal Pest Control Products Act as of February 1983. Some of these data are reproduced in Table 3.2. There are two basic ways to produce chlorophenols: one is to successively chlorinate phenol, and the other is to hydrolyze chlorobenzenes. The latter process, especially at higher temperatures, can produce dioxins (222). All technical and formulated products made from chlorobenzenes in this way are contaminated by dioxins to some degree (474). This process is no longer used to make the PCP available in North America. 2-MCP This product is prepared by the direct chlorination of phenol, passing gaseous chlorine over and into molten phenol at 50 to 150°C, which leads to both 2-MCP and 4-MCP. Fractional distillation is then used to separate the two isomers, which have a difference of 40 to 45C in their boiling points (See Table 2.2). Diazotized O-chloroaniline can also be used to prepare 2-MCP (161, 315). 3-MCP The commercial preparation of 3-MCP is from meta-chloroaniline through the diazonium salt (495). 4-MCP Parachlorophenol is prepared in a number of different ways: from chloroaniline through the diazonium salt, from diazotized parachloroaniline, from paranitrosophenol by a modified Sandmeyer reaction, by selective reduction of chlorobromophenols, and by direct chlorination of phenol followed by fractional distillation as mentioned under 2-MCP (161, 445). 2,4-DCP Phenol, or monochlorophenols, are chlorinated to produce 2,4-DCP; a patented process dissolves phenol in liquid SO2 and treats it with cold gaseous chlorine to yield 98% 2,4-DCP (442). 2,4,5-TCP The trichlorophenol, 2,4,5-TCP, is made by chlorination of phenol, by hydrolysis of the trichlorobenzene, or by alkaline hydrolysis of 1,2,4,5-tetrachlorobenzene under pressure at 180°C in the presence of aqueous NaOH and methanol. The hydrolysis methods result in contamination by dioxins, especially TCDDs, tetrachloro-p-benzodioxins, in the last method (222, 474). 2,4,6-TCP Chlorination of phenol is one method used to produce 2,4,6-TCP. The oxidation of O-dichlorobenzene to form O-chlorophenol, followed by chlorination with chlorine gas, is an alternate method (526). 2,3,4,5-TTCP The tetrachlorophenol, 2,3,4,5-TTCP, is a by-product of PCP production and is also made by the K2TeO3, potassium tellurate, catalyzed chlorination of phenol. The latter method produces only tetrachlorinated phenols (89, 442). 2,3,4,6-TTCP This tetrachlorophenol, 2,3,4,6-TTCP, is made by chlorinating phenol and also obtained commercially as a by-product of PCP manufacture at about 4% to 10% by weight. The K2TeO3 catalyzed reaction, as mentioned under 2,3,4,5-TTCP, is also used (442). 2,3,5,6-TTCP Chlorinating phenols is one method of making 2,3,5,6-TTCP. A low yield is also obtained as a by-product of PCP manufacture (89). The K2TeO3 catalyzed chlorination of phenol, as mentioned under 2,3,4,5-TTCP, is also used (442). PCP PCP may be made by chlorinating phenol, or by the hydrolysis of chlorobenzene. The latter process leads to contamination with dibenzo-p-dioxins (222, 474). Anhydrous aluminum chloride or ferric chloride are used as catalysts in the final chlorination stages. Mixtures of 2,6-DCP and 2,4,6-TCP with phenol may also be used as starting materials during chlorination, which proceeds in stages at progressively higher temperatures (161, 464). Chlorinating phenol is the only process in current use for the production of PCP imported into Canada.
As indicated in section 3.2, one method of producing chlorophenols, the hydrolysis of chlorobenzenes, produces dibenzo-p-dioxin contamination of the product to some degree. Table 3.3.1 gives the levels of some other contaminants in commercial 2,4-DCP. Since this product is used primarily to manufacture the herbicide 2,4-D, either as the acid, amine or ester, similar formulations of the contaminants are being distributed to the environment wherever 2,4-D is being used (91, 684). There are numerous reports in the literature from the 1970s and early 1980s of impurities in technical PCP formulations (222, 37, 217). The quality and quantity of commercial chlorophenol products vary widely. The actual quality and quantity of the product used to determine acute and chronic levels of chlorophenols for various organisms are not always reported in the literature. This causes several problems with literature values of toxic levels of chlorophenols. Quantitatively, the toxic level quoted will be too conservative when the product is not pure since a lower actual concentration of chlorophenol is present. Qualitatively, one can rarely be sure just how much of, or which of, the toxic effects are due to the chlorophenol, and how much is due to the contaminants (147). Since common contaminants in chlorophenols were dibenzo-p-dioxins, which are toxic at levels about 1x10-6 of the levels at which chlorophenols are toxic, a very low level of dioxin contamination may have masked the toxicity of the much more abundant chlorophenol. The manufacturing processes, and thus the levels and types of impurities, vary both with supplier, and with time and lot number of the product. Technical PCP contains a large number of impurities depending upon the manufacturing method. These include other chlorophenols, particularly TTCP isomers; PCDDs, polychlorodibenzo-p-dioxins; PCDFs, polychlorodibenzofurans; polychlorodiphenyl ethers, chlorinated cyclohexanes and cyclohexadienons; polychlorophenoxyphenols; hexachlorobenzene, and polychlorinated biphenyls, PCBs (199). The most toxic dioxin, 2,3,7,8-tetrachlorodibenzo-p-dioxin, was reported not to be found in chlorophenols used as wood preservatives (267); however, a conflicting report indicates that it was present in NaPCP used for this purpose (715). Table 3.3.2 lists the concentrations of chlorophenols present in some commercial products used in acute and chronic toxicity tests, as reported by the experimenters. Table 3.3.3 lists the major contaminants present in these products and Table 3.3.4 lists the major dioxins present. Table 3.3.5 gives the dioxin and furan analyses of three chlorophenol formulations. These four tables give some idea of the range and concentrations of compounds the test animals were subjected to, and which might have been responsible for some portion of the toxicity ascribed to the PCP. Typical contaminants for formulations used in wood preservation are <1 to 2000 mg/L of chlorinated dioxins, 100 to 1000 mg/L of chlorinated diphenylethers, 50 to 200 mg/L of chlorinated dibenzofurans, and about 10 g/L of chlorinated phenoxyphenols. One PCP formulation available in Sweden was 80% TTCP; PCP was only an impurity (222). The concentration of 2,3,7,8-TCDD dioxin in the current (1996) formulations of PCP by Vulcan Chemicals and KMG-Bernuth are regulated by the USEPA under the 1986 RPAR agreement at less than the detection limit of 1 µg/Kg (656). The PCP guideline would thus protect people from harmful effects due to dioxin contaminants in the PCP, at the known levels of this contamination. The RPAR agreement limits HCDD to a maximum of 4 mg/L and a mean of 2 mg/L (656). The HCB level may not exceed 75 mg/L. In practice the monthly mean HCDD is between 1.3 and 1.8 mg/L and no 2,3,7,8-TCDD is detectable at detection limits of 50 ng/L. There is no tetra- or penta PCDF at the detection limits of 10 µg/L, hexa PCDF ranges up to 64 mg/L and hepta PCDF up to 105 µg/L. "It is difficult to determine in retrospect which of the toxic effects reported in the literature are truly caused by pentachlorophenol and which are due to toxic contaminants. Our results suggest that the contaminants cause most of the alterations reported in rat livers" (320). "The contaminants associated with PCP may be a more serious threat to environmental and occupational safety than PCP itself" (127, 129). The effects of 2,3,7,8-dibenzo-p-dioxin on primates is documented by Allen and Miller (403). It is likely that some of the toxic effects in birds and mammals exposed to chlorophenols are actually caused by the many impurities present in technical and commercial formulations. Chloracne and porphyria tarda effects in the employees who manufacture 2,4,5-TCP, are likely due to the TCDD contaminants and not to the 2,4,5-TCP itself (480). More and varied toxic effects are reported from animals exposed to these commercial grades of PCP than from animals exposed to purified PCP (35, 38, 312, 316, 317, 318). Yolk sac edema and skull deformations, common in birds exposed to chronic levels of technical grade PCP, are nearly absent in similar tests done with purified PCP. In a chick edema bioassay, rabbit ear dermatitis assay and rat oral dose hematological effects assay, pure PCP had no effect except increased organ weights in livers and kidneys of rats given 30 mg/kg/day. Technical grade PCP containing 1980 mg/L octa- and 19 mg/L hexachlorodibenzo-p-dioxins, gave positive results in the bioassays and also caused altered blood chemistry and organ anatomy (317). Cattle fed pure PCP, technical grade PCP, and mixtures of the two at 20 mg/kg PCP for 42 days followed by 15 mg/kg for the next 4 months showed dioxin and furan levels in the liver and fat correlated with the proportion of technical PCP in the diet. Blood hexachlorobenzene levels rose concomitantly (572). The commercial mixture of PCP with its high contaminant levels, and relatively low PCP level, was more toxic than purified PCP or Dowicide EC-7, due to high levels of dibenzo-p-dioxins and phenoxyphenols. PCP, when purified, did not affect growth below 0.085 mg/L, and Dowicide EC-7 did not affect growth up to 0.139 mg/L (127). In addition to the variation in purity of the pentachlorophenol used in experiments, which ranged from 99%+ to 75%, the PCP was often used as the sodium salt, Na-PCP. Some experimenters (97) carried out parallel tests which showed differences in the LC50s between Na-PCP and PCP, but in many cases the two compounds are not clearly distinguished and are treated as being synonymous. The numbers reported will be different due to the difference in molecular weight of the two compounds, Na-PCP is 8% heavier and thus contains less PCP/mg than does pure PCP, and also due to the differences in the polarity, solubility and Ko/w of the compounds which affect uptake rates by organisms. The differences are well marked in short-term experiments, 12 to 24 hours, but almost disappear by 96 hours. Thus the effects are likely one of uptake rates and not important in long-term, low-level chronic effect exposures. At higher pH levels where dissociation is virtually complete this effect should not be significant. When it is known which compound was used, this is noted in the tables of effects on organisms, and Na-PCP or PCP is specified; some "PCP" entries are likely actually Na-PCP.
In spite of their relatively short half-lives and relative ease of degradation, chlorophenols are routinely found world-wide in water, soil, sediment and biota (11). This is due, at least in part, to their very widespread use, as well as to misuse, spills, and leaching from treated wood products and waste dumps. Most developed countries have found it necessary to restrict the use of chlorophenols, initially for domestic and agricultural uses, but increasingly for wood preservation uses as well (199). Chlorophenols, mostly PCP, were imported from the US and France into Canada but currently the only imports are from the US The world-wide production was about 30,000 tonnes in 1989; approximately 750 tonnes entered BC (199). About half of the BC total was used in anti-sapstain treatments on cut lumber. Chlorophenols have a relatively short half-life in water, biota and sediment, and once input stops, environmental levels are expected to drop quickly. Chronic input is required to maintain the current environmental levels (243). All of the chlorophenols have been detected in Kraft pulp mill effluent (705). The use of many chlorinated pesticides adds to the chlorophenol load to the environment since some of the breakdown products and metabolites of these pesticides are chlorophenols. The decay of vegetation produces phenols; wastewater from coal and wood distillation, petrochemical refining, steel mills, foundries, chemical plants, livestock dips, and domestic wastes also contain phenols. These phenols are converted to chlorophenols by chlorination in wastewater treatment plants (236). Our dependency on chlorine as a water treatment tool is responsible for much incidental chlorophenol production and input to the environment. Removal of organics from wastewater streams before chlorination, or conversion to UV and ozone as water sterilization techniques, for both wastewater and drinking water, would eliminate or greatly reduce this source of chlorophenol production and widespread distribution. The use of chlorophenols in the lumber industry has been the main contributor to the environment. Losses, spills, floods, leaching, at treatment plants and from treated wood, all contribute chlorophenols in large quantities, and chlorophenols are present in pulp and paper mill wastewater (258). The total annual runoff from lumber storage yards, expressed as pure PCP, is estimated at 916 kg to the lower Fraser River below Kanaka Creek, 523 kg to Burrard Inlet and 85 kg to Howe Sound at Squamish (271). Mackenzie et al., 1975 (673) found that for the period 1960 to 1973, 62 fish kills were reported in BC, 17 caused by pesticides. Four were associated with the use of PCP and TTCP for treatment of wood and poles. In May 1963, 1000 ocean perch were killed by PCP in Sooke Basin as a result of lumber treatment. In August 1972, 1000 trout, salmon and stickleback were killed by PCP in the Little Campbell River due to spraying of hydro poles. In Victoria Harbor in December 1972, 10 tons of herring and anchovy were killed by PCP from a pole and sawmill wood treating plant. In the Manquam Channel in October 1973, 500 shiners and 500 adult and juvenile coho salmon died from PCP and TTCP overflowing from a lumber treatment tank. MCPs MCPs are formed when drinking or effluent waters containing phenol are chlorinated; they are present in pulp and paper effluents and wood preservation waste. Microbial breakdown of pesticides like 2,4-D, 2,4,5-T, Silvex, Ronnel, Lindane and benzene hexachloride, produce MCPs in the environment (372, 591). 2-MCP The herbicide 2,4-D is broken down by Pseudomonas to 2-MCP (441). The chlorophenol 2-MCP is formed in the 1.7 µg/L range during chlorination of municipal waste water (480, 591). This compound is a major cause of odors. 3-MCP Chlorinated sewage effluents have been found to contain 3-MCP in the 0.5 µg/L range (591). Breakdown of 2,3,4,5-TTCP by soil bacteria produces 3-MCP (17, 606). 4-MCP Chlorinated sewage effluent contains 4-MCP in the 0.7 µg/L range (591). DCPs These compounds are found in leachate from dump sites and landfills (593, 594). There is no consensus yet on whether these compounds are found in significant levels in chlorinated wastewater or cooling water (591, 595, 183, 188).
2,4-DCP The chlorophenol, 2,4-DCP, is formed in the nano- to micro-molar range during chlorination of municipal wastewater (480), and is a major odor causing compound. It is formed as a breakdown product of the herbicides 2,4-D and Nitrofen (495). Kraft pulp mill effluents contain 2,4-DCP (592). 2,5-DCP When 2,4,5-T breaks down by photolysis in aerated water, 2,5-DCP is a product (493). 2,6-DCP The chlorophenol, 2,6-DCP, is formed in the nano-to-micro-molar range by the chlorination of municipal wastewater (480), and is a major cause of odors. It is also produced in the pulp mill bleaching process (267). 3,4-DCP In soil, 3,4-DCP is found as a breakdown product of PCP (294). Breakdown of 2,3,4,5-TTCP by soil bacteria produces 3,4-DCP (17, 606). 3,5-DCP In soils 3,5-DCP is found as a breakdown product of PCP (294). TCPs TCPs occur in wastes from wood preserving and pulp and paper industries and form, in water and wastewater containing phenol, when chlorination occurs. TCPs are produced as degradation products of Lindane and 2,4,5-T in soil and in livestock, and are thus found in farmland or agricultural land runoff and also in landfill drainage from industrial or municipal wastes (183, 372, 592, 593, 594). 2,3,4-TCP The degradation of Lindane in soil results in the formation of 2,3,4-TCP (606). 2,3,5-TCP The degradation of Lindane in soil results in the formation of 2,3,5-TCP. Breakdown of 2,3,4,5-TTCP and 2,3,5,6-TTCP by soil bacteria also produces 2,3,5-TCP (17, 606). 2,3,6-TCP Breakdown of 2,3,5,6-TTCP by soil bacteria produces 2,3,6-TCP (17, 606). 2,4,5-TCP The primary degradation product of the herbicide 2,4,5-T, is 2,4,5-TCP (480, 176). The chlorination of wastewater containing phenol results in the production of 2,4,5-TCP (225). There is evidence that 2,4,5-T is also a metabolite or primary degradation product of other pesticides including Silvex, Ronnel, Lindane and benzene hexachloride (480). In leachate from Vancouver industrial and municipal wastes, 2,4,5-TCP has been found at levels up to 2.4 mg/L (594). Breakdown of 2,3,4,5-TTCP and 2,3,4,6-TTCP by soil bacteria, produces 2,4,5-TCP (17, 606). It is also produced in the pulp mill bleaching process (274).
2,4,6-TCP Corn and peas metabolize pentachlorocyclohexene and 1,3,5-trichlorobenzene
to 2,4,6-TCP (230). One of the metabolic breakdown products of
the insecticide Lindane is 2,4,6-TCP (225, 226, 275). Kraft pulp
mill effluent has been shown to contain 2,4,6-TCP (592), and
levels up to 3.12 mg/L were found in municipal and industrial
wastes in Vancouver (594). It has been estimated that when water
containing phenol is chlorinated, 40 to 50% of the chlorophenols
formed consist of 2,4,6-TCP (183). It is also one of the predominant
chlorophenols produced in the pulp mill bleaching process (274). Agricultural lands are sources of tetrachlorophenols to surface waters. They are used in herbicides and as wood preservatives for farm buildings and fences (8). While TTCPs are not likely formed by chlorination of sewage, they are present due to industrial discharges (594). Leachates from landfill sites contain TTCPs (594) and TTCPs form as degradation products from PCP, but the main source is waste from wood preserving industries: levels up to 2.1 mg/L have been found in such discharges (594). 2,3,4,5-TTCP The World Health Organization, WHO, has determined that 2,3,4,5-TTCP is a metabolite of the pesticides Lindane and PCP (522); it is also a degradation product of PCP and a by-product of PCP production (89). PCP is broken down by sunlight to form 2,3,4,5-TTCP which persists in fish (201). 2,3,4,6-TTCP This material is found in fly ash from municipal incinerators and thermal power stations which burn peat, wood waste, PCB- contaminated and non-contaminated oils, and municipal wastes (274, 290). It is also formed as a by-product in the manufacture of PCP. Flue gases from fireplaces and other wood burning processes, and smoke from slash, forest and grass fires all release 2,3,4,6-TTCP to the atmosphere (290). The waste from wood preservation facilities is a source of 2,3,4,6-TTCP, and PCP (291). It is also produced in the pulp mill bleaching process (267). 2,3,5,6-TTCP This congener is found in fly ash from municipal incinerators and thermal power stations which burn peat, wood waste, PCP -contaminated and non-contaminated oils, and municipal wastes (274). The waste from wood treatment facilities contains 2,3,5,6-TTCP and PCP (291). PCP is broken down by sunlight to form 2,3,5,6-TTCP which persists in fish (201).
PCP Incinerators, fly ash, flue gases, slash fires, fireplaces and other wood burning processes, all release PCP to the atmosphere (290). Hexachlorobenzene and pentachlorobenzene are common waste products which natural microbial metabolism converts to PCP (12, 216). PCP was measured in sewage treatment plant effluents, over the range of 0.065 to 1.300 µg/L, in 13 samples from 7 plants in Ontario. PCP is used in wood preservatives to treat farm buildings, fence posts, telephone poles, and compost boxes, and is also used in herbicides. Such uses contribute to diffuse runoff to water courses (8). Wastes from other industries and the leachate from landfill sites in Vancouver contain PCP (594). The concentration of NaPCP used in drilling fluids as a bactericide, is about 700 to 1400 mg/L. Used fluid is put into sumps which could range from 2,800 to 11,300 m3 for a partial season of operations. Due to flooding, wash outs, storms and other accidents, this fluid is often released to the environment and contaminates local surface waters (640). Between 1972 and 1982, EPS documented 26 NaPCP spills in BC; some resulted in fish kills in surface waters and others caused ground water contamination. The usual cause was flooding of dip tanks and drive through tanks by heavy rains, and surface run-off of drip areas after rainstorms (271). In 1977 a railroad box-car was used to ship PCP from the production plant in Alberta to a pole-treatment plant. The box-car was then used to ship feed oats from Northern Alberta to Thunder Bay, Ontario. Finally it was used to ship feed-grain to eastern Ontario. The feed-grain was sufficiently contaminated with PCP that cattle would not to eat it! Car sweepings had 2 µg/kg of PCP (650).
3.5.1 Air PCP The outer layers of treated wood contain up to several hundred mg/kg of PCP. Due to volatilization, air levels of PCP in proximity to large amounts of treated wood, or in confined spaces, will be significantly higher than background. Airborne levels of PCP at production and wood preservation sites range from several mg/m3 to 500 mg/m3 (27). Two background air sampling stations in the mountains above La Paz, Bolivia, at 5200 m, measured 0.93 and 0.25 µg PCP/1000 m3 of air, and four Antwerp, Belgium samples varied from 5.7 to 7.8 µg PCP/1000 m3 of air (688). The level of PCP in Burlington Ontario rainwater was 10 µg/L in 1982 (685).
3.5.2.1 Drinking Water Chlorophenol residues in drinking water rarely exceed several µg/L and are usually below one µg/L. 3.5.2.2 Ambient Water Table 3.5.1 gives some chlorophenol levels found in Fraser River water (269, 720) and Table 3.5.2 gives water and sediment levels of PCP and TTCPs for several British Columbia sites. Table 3.6.1 gives summaries of the chlorophenol levels found in the water of the Fraser Estuary between 1973 and 1987 (693). The range of concentrations of chlorophenols detected along the BC coast in the general proximity to bleached pulp mills is: 2,4,6-TCP, 1.6 to 20.0 µg/L; 2,3,4,6-TTCP, 1.0 to 7.1 µg/L and PCP, 1.7 to 2.8 µg/L (713). Chlorophenols (92% PCP and 8% TTCPs) were sampled in the waters of railway and utility right-of-way ditches of the lower mainland of BC. The ditches flowed into salmon bearing streams. The water adjacent to poles in utility right-of way ditches contained a mean of 1408 µg/L and water 4 m downstream contained a mean of 13.6 µg/L. Water adjacent to poles in railway right-of way ditches contained a mean of 225 µg/L and 3.8 µg/L 4 m downstream. Water levels adjacent to the poles exceeded the LC50 for salmonids and the downstream levels were high enough to cause chronic effects (719). TCPs Rhine river water in the Netherlands, sampled in 1978, contained 0.04 to 0.63 µg/L of 2,4,6-TCP and 2,4,5-TCP. Generally, samples from the Fraser River at Hansard, Hope and Marguerite do not show measurable levels of chlorophenols, but in the period from November 1990 to March 1991, there were six detectable values for TCPs of 0.07, 0.08, 0.1, 0.11, 0.13 and 0.17 µg/L at the Marguerite site (698). TTCPs In British Columbia surface waters, TTCP levels exceeded 1 µg/L in 1979, but were only 0.1 µg/L in 1986 (87, 269, 720). TTCP levels up to 5.2 µg/L were found in British Columbia waters in 1984 (88). Generally, samples from the Fraser River at Hansard, Hope and Marguerite do not show measurable levels of chlorophenols, but in the period from November 1990 to March 1991 there were three detectable values for TTCPs of 0.05, 0.07 and 0.16 µg/L at the Marguerite site (698). 2,3,4,6-TTCP Water samples taken from the North Arm of the Fraser River in 1985 contained 0.002 to 15.2 µg/L of 2,3,4,6-TTCP (86). PCP "Uncontaminated" areas have background PCP levels at or below the ng/L detection limit in water. Levels several orders of magnitude higher are found near industrial discharges and in areas that have been subject to spills. Levels reach mg/L in chronically contaminated areas (8, 9, 201, 289, 291, 299, 300). PCP is generally high and persistent in water and sewage samples (201, 212), particularly in heavily industrialized areas such as the Great Lakes. Stream mouths and near-shore areas along the Canadian Great Lakes contained 0.005 to 22.0 µg/L of PCP in 78 of 85 water samples tested. A Lake Michigan watershed contained 0.1 to 40.0 µg/L (225). Rhine river water in the Netherlands contained 0.15 to 1.5 µg/L PCP in a 1978 survey (225). Drinking water in Dade County, Florida, was analyzed for PCP; municipal supplies ranged from <0.030 to 0.340 µg/L, with a mean of 0.098 µg/L and wells ranged from <0.030 to 0.110 with a mean of 0.044 µg/L. These levels were low enough that blood serum levels of residents did not differ when drinking these two sources of water (576). Up to 7.3 µg/L PCP have been found in British Columbia waters (88). Water samples in the North Arm of the Fraser River contained 0.002 to 2.80 µg/l of PCP (86) and PCP levels in British Columbia surface waters exceeded 1 µg/L in 1979 but were only 0.09 µg/L in 1986 (87, 287). Generally, samples from the Fraser River at Hansard, Hope and Marguerite do not show measurable levels of chlorophenols, but in the period from November 1990 to March 1991 there was one detectable value for PCP of 0.22 µg/L at the Marguerite site (698). Segments of pressure treated poles were held in continuously circulated water at various pH levels and in dilute HCl for 30 days. Leaching rates ranged from 6.33 x 10-3 to 1.67 x 10-4 mg PCP/kg water / square inch of wood. The amount of PCP in solution increased with exposure time and with higher pH. Solutions reached their peak leaching rate in 1 to 3 days. The maximum concentration reached after 30 days was 65.5 mg/L in the water buffered at pH 9 (724).
Chlorophenol residues in fruits and vegetables are usually below 10 µg/kg, as are levels in all meats except liver, which may reach 100 µg/kg. Fish skeletal muscle is usually below 4 µg/kg. Milk from southern Ontario dairies was analyzed for PCP, 2,3,4,6-TTCP, 2,4,5-TCP and 2,4,6-TCP. Detection limits were 0.1 µg/L for PCP and 1 µg/L for the other congeners. No chlorophenols were detected (649). Table 3.5.3 gives the levels of PCP and TTCP found in Canadian food samples from 1975 to 1978. The samples were collected in Alberta. PCP Food products often contain PCP (27, 170), usually from contact with treated shipping, storage or packaging materials. Levels of 1 to 100 µg/kg have been found in powdered milk, soft drinks, bread, candy bars, rice, noodles, cereal, sugar and wheat (27). Food fish contain PCP at 1 to 4 µg/kg (31). The PCP metabolite, pentachloroanisole, has been found at levels of 1 to 18 µg/kg in broiler chickens when the birds are raised on wood shavings derived from treated wood (32).
People are subjected to chlorophenols, mostly PCP, in their food, water and air. For the U. S. A. and Germany, estimates are 6 µg/d in food, 2 µg/d in water and 2 µg/d in air. Other sources include veterinary supplies, fabrics, disinfectants, photographic solutions, rug shampoos and pharmaceuticals (199). 2,4,5-TCP A survey of the general population of the US showed only 1.7% of the urine samples were positive for 2,4,5-TCP, with a mean of <5.0 µg/L and a maximum of 32.4 µg/L (22). PCP Seminal
FLuid Adipose
Tissues Blood Plasma/Serum Occupational exposures in the wood preservation industry result in human serum levels in the µg/L to mg/L range, while the general public levels are in the µg/L range. Urine and fat levels are similar. Workers in a PCP plant in Idaho were checked monthly for serum and urine levels. Serum levels ranged from 0.348 to 3.963 mg/L, with a mean of 1.372 mg/L. Controls had levels of 0.038 to 0.068 mg/L, with a mean of 0.048 mg/L (573). The median plasma level of PCP in 18 workers in a PCP processing factory, with 12 years mean exposure, was 0.25 µg/L. The range of values was 0.02µg/L to 1.5µg/L (721). In an environment where the PCP level in the air ranged from 0.3 to 180 µg/m3, 10 workers with 4 to 24 years exposure had serum concentrations of 38 to 1270 µg/L (722). Urine Samples People in
the USA. who were not exposed as part of their jobs had PCP
levels in
their urine which ranged from 1 to 193 µg/L
(22). Over 400 urine samples from the general public were analyzed
for PCP with a detection limit of 0.005 mg/L. The maximum value
found was 0.193 mg/L, the mean value 0.0063 mg/L and 84.8% of
the samples had detectable PCP levels (127, 571). One sample
of 117 people had a mean of 40 µg/L with a range of <1
to 1800 µg/L and another sample of 173 people had a mean
of 44 µg/L with a range of 3 to 570 µg/L (24). In
Britain, six people ranged from 2 to 11 µg/L (26). In Japan
20 people ranged from 10 to 50 µg/L (25), and 60 students
at a Florida University had a mean of 20 µg/L with a range
of 9 to 80 µg/L (27). Chlorophenols are preferentially adsorbed onto organic particles in the water, and organic sediments become repositories (220); much of the PCP will remain on the sediments but the other chlorophenols will tend to become distributed throughout the other environmental compartments. Table 3.5.2 gives some sediment levels of PCP and TTCPs for several British Columbia sites in 1978. These levels varied from 5 to 270 µg/kg dry weight (87). In the lower Fraser River sediment, PCP and TTCPs (mostly 2,3,4,6-TTCP) varied from less than 3 to 5 µg/kg dry weight in 1987. These were lower levels than those found in 1985 in a similar survey, and much lower than the 1978 data in Table 3.5.2, indicating less use of chlorophenols, better waste management, or deposition of fresh, less contaminated sediments on top of the older sediments. Sediment size also affects the adsorption and chlorophenols do break down, so the net level measured is a function of breakdown and deposition rates (537). It appears that the concentration of chlorophenols in surface sediments is decreasing in BC Table 3.6.1 gives summaries of the chlorophenol levels found in the sediments of the Fraser Estuary between 1973 and 1987 (693). Chlorophenols (92% PCP and 8% TTCPs) were sampled in the sediments of railway and utility right-of-way ditches of the lower mainland of BC, ditches which flowed to salmon bearing streams. The sediments adjacent to poles in utility right-of way ditches contained a mean of 139 mg/kg and sediments 4 m downstream contained a mean of 0.3 mg/kg. Sediments adjacent to poles in railway right-of way ditches contained a mean of 49.7 mg/kg and 0.4 mg/kg downstream. Sediments at the base of utility poles had a mean value of 2168 mg/kg and soils next to railway ties averaged 38.6 mg/kg. These are all expressed on a wet-weight basis; the mean moisture content was 35 % with a range of 21 to 57 (719).
TTCPs In British Columbia, sediment levels of TTCPs in excess of 100 µg/kg were found in 1979 and up to 63 µg/kg was found in 1986. 2,3,4,5-TTCP and 2,3,5,6-TTCP PCP is broken down by sunlight to form 2,3,4,5-TTCP and 2,3,5,6-TTCP, which persist in sediments (201). 2,3,4,6-TTCP The concentration of 2,3,4,6-TTCP in sediments of a contaminated lake in Finland was 33.4 to 50.1 µg/kg dry weight (599). PCP Sediment levels of PCP are below the µg/kg detection limits in uncontaminated background areas, but rise to mg/kg levels in chronically contaminated areas (8, 91, 201, 289, 291, 299, 300). In heavily industrialized areas, such as around the Great Lakes, PCP levels are generally high and persistent in lake sediments (13, 103, 201, 212), soils (213) and leaf litter (13, 201). In British Columbia sediment levels of PCP in excess of 100 µg/kg were found in 1979 and 107 µg/kg was found in 1986. Table 3.5.2 gives water and sediment levels of PCP and TTCPs for several British Columbia sites. These sites are generally just downstream from, or near, wood treatment plants, and subject to run-off. The migration of PCP from treated power poles into the surrounding soil showed a gradient with a mean value of 658 mg/kg adjacent to the pole, 3.4 mg/kg at 30 cm from the poles and 0.26 mg/kg at 150 cm. This latter value is not significantly different from background in industrialized areas. Migration is minimal and biodegradation keeps PCP levels in the environment down (191). The leaching of PCP from 100 utility poles in the USA was studied and showed tremendous variability both at a site and between sites. Generall surface samples had higher levels than subsurface samples and PCP concentrations dropped rapidly with distance from the pole. The maximum PCP concentration found ranged from 0.14 to 1500 mg/kg but the maximum at most poles was under 100 mg/kg. The mean maximum found was 190 mg/kg (± 340 mg/kg) and the median was 34 mg/kg. Samples collected at all depths and 3, 8, 18 30 and 48 inches from the pole, had 55%, 80%, 92%, 95% and 95% of the PCP concentrations under 1 mg/L. All but 3 samples collected more than 3 inches from the poles had PCP values under 500 mg/L and those collected over 8 inches from the poles had PCP values under 50 mg/kg (723).
Table 3.5.4 gives the levels of various chlorophenols in biota from the Fraser River (269, 720). In most biota, PCP levels were below the 1 to 10 µg/kg wet weight level; near wood treatment facilities levels were relatively high (289, 305). Fish upstream in the Fraser River had TTCPs and PCP at the detection limits of 1 to 20 µg/kg; in the lower reaches where contamination from industrial effluent occurred, levels reached 40 to 90 µg/kg except for sculpins, which had a mean of 50 and a peak, near treatment facilities, of 100 µg/kg (87). Chlorophenols were also found in the Fraser River near Prince George and Quesnel, and in the livers of mountain whitefish, Prosopium williamsonii, and largescale suckers, Catostomus macrocheilus, which live in this reach. Juvenile chinook salmon also overwinter in this reach of the Fraser River and were exposed to high levels of PCP during winter low flows in the river (203). Table 3.6.1 gives summaries of the chlorophenol levels found in the organisms of the Fraser Estuary between 1973 and 1987 (693). The data in this section is given on a wet weight basis. DCPs Only large fish in the lower Fraser River, BC, had measurable DCP levels (262). In Canagagique Creek, Ontario, high levels of 2,6-, 2,4- and 3,4-DCP were found in fish; up to 1693 µg/kg (302). In the Weser estuary and German Bight, Europe, the polychaete, Lanice conchilega, contained 11.8 µg/kg of 2,4- and 2,5-DCPs (641, 642, 643). 2,4-DCP Marine organisms near Saint John, NB, living in waters receiving pulp mill effluent, contained the following amounts of 2,4-DCP, as µg/g of lipid, measured as methyl ethers, in the specified tissue; DCP recoveries were only about 45% (8). Maya arenaria
Crangon septemspinosa
Pseudopleuronectes americanus
Alosa pseudoharengus
Alosa sapidissima
Osmerus mordaz
Acipenser oxyrhynchus (Sturgeon, liver), 0.37 Microgadus tomcod (Tomcod, muscle), detectable, 3.73, 2.0
TCPs TCPs were measured in the Lower Fraser River fish in 1988, with a detection limit of 1 µg/kg of fish muscle tissue. TCPs were not detected in largescale suckers from the main arm, threespine stickleback from the north arm and peamouth chub and staghorn sculpins from the main and north arms. In the main stem, mean values for peamouth chub were 31 µg/kg, for northern squawfish 13 µg/kg, for largescale suckers 11 µg/kg, and for redside shiners 38 µg/kg. In the north arm values were 12 µg/kg for largescale suckers, 38 µg/kg for northern squawfish, and 28 µg/kg for starry flounder (535). TCPs were rarely found in fish tissues from the Fraser River (262). In 1987 measurements were made of trichlorophenols in lower Fraser River benthos. The wet weights found were 80 µg/kg in amphipods, 100 µg/kg in other crustaceans, 20 to 60 µg/kg in chironomids, 40 to 400 µg/kg in pelecypods, 200 µg/kg in leeches, <20 to 80 µg/kg in lampreys, 60 to 2000 µg/kg in oligochaete worms and 30 to 2000 µg/kg in polychaete worms (537). 2,4,5-TCP In the Weser Estuary and German Bight the polychaete worm, Lanice conchilega, contained 19.3 µg/kg of 2,4,5-TCP (641, 642, 643). 2,4,6-TCP In contaminated lakes in Finland, reported tissue levels of 2,4,6-TCP include: 13.6 to 17.3 µg/kg in pike, 4.67 to 55.9 µg/kg in roach, 1.44 µg/kg in clams, 4.96 to 6.86 µg/kg in sponge and 2.45 µg/kg in plankton (599). In the Weser Estuary and German Bight the polychaete, Lanice conchilega, contained 26 µg/kg of 2,4,6-TCP (641, 642, 643). Marine organisms near St. John N.B., living in water receiving pulp-mill effluents, contained the following amounts of 2,4,6-TCP, as µg/g of lipid, measured as methyl ethers in the tissue specified. TCP recoveries were only about 40% from the columns (8). Mya arenaria
Crangon septemspinosa
Pseudopleuronectes americanus
Alosa pseudoharengus
Alosa sapidissima
Osmerus mordax
Microgadus tomcod
Acipenser oxyrhynchus
TTCPs In the southwestern BC area starry flounder tissues contained 0.19 to 2.52 mg/kg of TTCPs; near wood treatment facilities TTCP levels in tissue may reach 20 µg/kg in crabs and 690 µg/kg in mussels (87). A spill at Elk Falls, Campbell River, caused tissue levels of TTCPs of 3530 µg/kg in the invertebrates and 800 µg/kg in the algae (305). Sculpins in the lower Fraser River near treatment facilities had liver levels of TTCPs of 1600 µg/kg (87). TTCPs were measured in fish from the lower Fraser River in 1988. The detection limit was 1 µg/kg dry weight of fish muscle tissue. Tetrachlorophenols were not detected in largescale suckers from the north arm, northern squawfish from the mainstem, starry flounder from the main arm, staghorn sculpins and threespine sticklebacks from the north arm, and peamouth chub living at any site. In the mainstem, largescale suckers had 6 µg/kg and redside shiners 50 µg/kg. Main arm levels were 15 µg/kg in largescale suckers and staghorn sculpins and 76 µg/kg in northern squawfish. In the north arm, northern squawfish had 33 µg/kg and starry flounders 1 µg/kg (535). Levels of TTCPs in lower Fraser River benthos in 1987 were below 20 µg/kg in amphipods and crustaceans, 10 to 100 µg/kg in chironomids, <20 to 1500 µg/kg in pelecypods, 500 µg/kg in leeches, 20 to 200 µg/kg in lampreys, 200 to 3000 µg/kg in oligochaete worms and 200 to 1000 µg/kg in polychaetes (537). In the Weser Estuary and German Bight, the polychaete worm, Lanice conchilega contained 67 µg/kg of 2,3,4,6- and/or 2,3,5,6-TTCP (641, 642, 643). 2,3,4,5-TTCP In the Weser Estuary and German Bight the polychaete worm, Lanice conchilega contained 7 µg/kg 2,3,4,5-TTCP (641, 642, 643).
PCP The levels of PCP in fish are generally high and persistent in the Great Lakes (201, 212) and in industrialized areas generally. Starry flounder tissues in southwestern B .C. contained 0.77 to 2.77 µg/kg PCP on a wet weight basis (87). Near wood preservation facilities the PCP tissue levels may reach 17 µg/kg in crabs, 20 µg/kg in mussels, and 1700 µg/kg in polychaete worms (87, 303). After a PCP spill in Surrey, the tissue levels in Boundary Bay organisms reached 67 to 116 µg/kg in crabs, 171 to 563 µg/kg in oysters and 83 to 108 µg/kg in clams. These levels dropped below detection in 3 months (304). A spill at Elk Falls, Campbell River, caused PCP level of 4560 µg/kg in invertebrates and 3330 µg/kg in algae (305). Sculpins in the lower Fraser River near treatment facilities had liver levels of PCP of 2100 µg/kg (87). PCP was measured in fish from the lower Fraser River in 1988. The detection limit was 1 µg/kg dry weight of fish muscle tissue. PCP was not detected in threespine stickleback from the north arm. Mean values in the mainstem were 8 µg/kg for largescale suckers, 10 µg/kg for northern squawfish and peamouth chub, and 19 µg/kg for redside shiners. In the main arm largescale suckers had 6 µg/kg, northern squawfish and staghorn sculpins 4 µg/kg and starry flounders 7 µg/kg. North Arm fish contained 3 µg/kg in largescale suckers, peamouth chub and staghorn sculpins, and 11 µg/kg in northern squawfish (535). PCP measurements made in 1987 on lower Fraser River benthos found, on a wet weight basis, <20 µg/kg in amphipods, 50 µg/kg in crustaceans, 20 to 300 µg/kg in chironomids, 20 to 2500 µg/kg in pelecypods, 800 µg/kg in leeches, 100 to 3200 µg/kg in lampreys, 30 to 4200 µg/kg in oligochaete worms and 200 to 1000 µg/kg in polychaete worms. A survey of PCP in a New Brunswick estuary indicated low levels of PCP in almost all samples taken. Levels ranged from 10.8 µg/kg (wet weight) in white shark livers to 0.36 µg/kg in double-crested cormorant eggs (31). Marine organisms near St. John, N.B., living in pulp mill effluent receiving waters, contained the following PCP levels in the specified tissues, measured as µg/g lipid as methyl ethers (8). Mya arenaria
Crangon septemspinosa
Pseudopleuronectes americanus
Alosa pseudoharengus
Alosa sapidissim
Osmerus mordax
Acipenser oxyrhynchus
Microgadus tomcod (Tomcod, muscle), 0.43 to 5.36
In the Weser Estuary and German Bight, PCP levels reached 117.5 µg/kg in the polychaete worm, Lanice conchilega, and 4.6 µg/kg wet weight in the actinian, Sagartia troglodytes (641, 642, 643). In Surinam, NaPCP was used at 3.5 to 4.0 kg of 85% active material per 20 L of water to control water snails, Pomacea glouca. Snail tissue levels reached 36.8 ng/kg wet weight. Dead frogs, Pseudis paradoxa, and three species of fish, all dead, from the rice fields had 8.1 ng/kg, 31.2 ng/kg, 41.6 ng/kg and 59.4 ng/kg of PCP on a wet weight basis, respectively. Live fish of the same species from nearby unsprayed ditches contained 1.77, 8.76 and 13.4 ng/kg of PCP. These snails were a major food component of several bird species which frequented the rice fields (644). Fish from the Bay of Quinte on the north shore of Lake Ontario contained >200 µg/kg of PCP on a whole fish, wet weight basis (8). Lake Superior fish had whole fish PCP concentrations of 0.1 to 1 mg/kg in Salvelinus namaycush (lake trout) and Salvelinus namaycush siscowet (fatty lake trout), and 0.02 to 0.60 mg/kg in Coregonus clupeaformis (lake whitefish) (8). Cows housed in a barn constructed partly of PCP treated wood, had blood PCP levels from 270 to 570 µg/kg. PCP was found in bone marrow, fat, serum and liver (645, 646, 647, 648). In 1980, 10 lake trout from the eastern basin of Lake Ontario (Main Duck Island) had PCP levels below the detection limit of 0.5 µg/kg wet weight, as did six lake trout from the western basin (Port Credit). The PCP levels in five of the western trout were 2, 3, 5, 10 and 11 µg/kg wet weight (686). In 1979 young spot-tail shiners from Niagara-on-the-Lake and Centre Creek, Lake Erie had maximum levels of PCP and 2,4,6-TCP of 28 and 33 µg/kg wet weight, respectively, on a whole fish basis. The maximum level of 2,4,5-TCP at Niagara-on-the-Lake was 22 µg/kg (687).
Table 3.6.1 gives summaries of the chlorophenol levels found in the organisms, water, and sediments of the Fraser Estuary between 1973 and 1987 (693). Chlorophenols are used as broad spectrum biocides world-wide; residues and breakdown products are ubiquitous in air, water, sediment, and organisms. The major use has been as an anti-sapstain fungicide in the cut lumber industry, but this use is rapidly being phased out. They are also used as antiseptics and organic feedstocks for pesticide manufacture. Many commercial products contain chlorophenols (Table 3.2) and they are also used as preservatives in packaging materials. They are generally made by chlorinating phenols and by hydrolysis of chlorobenzenes. Dioxins were common byproducts of their manufacture, especially at high temperatures and using hydrolysis processes. Tables 3.3.1 to 3.3.5 give contaminant levels in commercial chlorophenol products. It can sometimes be difficult to decide whether an effect on biota is due to the contaminant or the chlorophenol. The chlorination of wastewater with high organic loads, such as sewage, leads to chlorophenol production at low levels; this practice is widespread. The major sources are wood treatment facilities and pulp and paper mills; effluents and spills from these plants are responsible for a number of fish kills. Fly ash from incinerators, power stations, fireplaces, and slash and forest fires also distribute chlorophenols widely in the environment.
|
||||
|
|
