Dichlorophenols, toxicities

Effects in Animals. The LD ia rats for all light chlorophenols, irrespective of the administration route, ties between 130 and 4000 mg/kg body weight. The toxicity of these compounds ia order of increasing strength is tetrachlorophenols > monochloropheno1 s > dichlorophenols > trichlorophenols when the chlorophenol is administered either orally or by subcutaneous iajection. 

Variations in the manufacturing process of 2,4,5-trichloro- and pentachlorophenol (but not 2,4-dichlorophenol) have sometimes resulted in contamination of the product by small amounts of heterocyclic impurities (4,5). Of these, the chlorinated dibenzo-p-dioxins such as TCDD (2,3,7,8-tetrachlorodibenzo-p-dioxin) have received much scientific and public attention because of their real or potential toxicity 6, 7), [Chick edema factor, a curious toxicological problem to poultry producers for several years, has been shown to be composed of chlorodibenzo-p-dioxins (8).]... 

Conversion of a toxic organic compound to a nontoxic organic compound. The pesticide 2,4-D can be detoxified microbially to 2,4-dichlorophenol. 

TCP), and pentachlorophenol (PCP), in order of abundance. Minor amounts of other trichlorophenols and dichlorophenols may also be present, as well as recalcitrant polychlorinated phenoxyphenols (PCPPs) and PCDD/Fs as impurities [75, 76]. In Finland, approximately 30,000 tons of CP products were used between 1934 and 1988, when they were banned because of their potential toxicity to humans and the environment [77, 78]. The careless manufacturing and application of wood preservatives together with the lack of suitable waste disposal caused massive contamination of river sediments and sawmill sites. For example, the river Kymijoki in southern Finland was identified as the largest source of dioxins accumulating in fish in the entire Baltic area. Similar products were used in other European countries, especially Nordic countries with a large forestry industry, such as Sweden [79]. 

Hodson, P.V., R. Parisella, B. Blunt, B. Gray, and K.L.E. Kaiser. 1991. Quantitative structure-activity relationships for chronic toxicity of phenol, p-chlorophcnol, 2,4-dichlorophenol, pentachlorophenol, p-nitro-phenol and 1,2,4-trichlorobenzene to early life stages of the rainbow trout (Oncorhynchus mykiss). Canad. Tech. Rep. Fish. Aquat. Sci. 1784. 56 pp. 

Figure 8. The bioconcentration ratios of chlorophenols in goldfish at 1 h exposure to their media as a function of the difference between pH and pKa. 4-CP 4-chlorophenol, 2,5-DCP 2,5-dichlorophenol, 3,5-DCP 3,5-dichlorophenol, 2,4,6-TCP 2,4,6-trichlorophenol, PCP pentachlorophenol, 2-CP 2-chlorophenol, 3-CP 3-chlorophenol, 2,4-DCP 2,4-dichlorophenol, 2,3-DCP 2,3-dichlorophenol, 2,4,5-TCP 2,4,5-trichlorophenol, 2,3,4,6-TCP 2,3,4,6-tetrachlorophenol, 2,6-DCP 2,6-dichlorophenol. Reprinted from [185] Water Res., 29, Kishino, T. and Kobayashi, K. Relation between toxicity and accumulation of chlorophenols at various pH, and their absorption mechanism in fish , pp. 431-442. Copyright (1995), with permission from Elsevier...

EPA. 1988b. Computer printout (CIS) 1977 production statistics for chemicals in the Federal Register. 1979. Petition to remove ethylbenzene, phenol, 2,4-dichlorophenol, 2,4,5- trichlorophenol and pentachlorophenol from the 307(a)(1) list of toxic pollutants. US. Environmental Protection Agency. Fed Reg 44 64555-64559. 

Gersich, F.M. and Milazzo, D.P. Chronic toxicity of aniline and 2,4-dichlorophenol to Daphnia magna Strans, BuU. Environ. Contam. Toxicol, 40(l) l-7, 1988. 

Several chlorophenols, including 2,5-dichlorophenol, have been identified in laboratory animals exposed to lindane. This indicates that the presence of 2,5-dichlorophenol is fairly specific, but not completely specific, for 1,4-dichlorobenzene exposure. Information on the analytical methods commonly used to detect and quantify 1,4-dichlorobenzene in biological samples is presented in Section 6.1. There are currently no data available to assess a potential correlation between the values obtained with these measurements and the toxic effects observed in humans or laboratory animal species. 

Toxicology. 2,4-Dichlorophenol (2,4-DCP) is an uncoupler of oxidative phosphorylation toxic manifestations include central nervous system depression followed by increased respiration, hyperthermia, increased blood pressure, progressive weakness, and cyanosis. 

Office of Pollution Prevention and Toxics, US EPA, OSHA, Div of Surveillance, Hazard Evaluations and Field Studies, NIOSH, CDC Occupational fatalities associated with 2,4-dichlorophenol (2,4-DCP) exposure, 1980-1998. MMWR Morb Mortal Wkly Rep 49(23) 516-518,Jun 16, 2000... 

Borzelleca JF, Hayes JR, Condie LW, et al Acute and subchronic toxicity of 2,4-dichlorophenol in CD-I mice. Fundam Appl Toxicol 5 478-486, 1985... 

Exon JH, Roller LD Toxicity of 2-chlorophenol, 2,4-dichlorophenol, and 2,4,6-trichlorophenol. In Proceedings of 5th Conference Water Chlorination Chem Environ Impact Health, pp 307-350, 1985... 

Exon JH, Koller ED Toxicity of 2-chlorophe-nol, 2,4-dichlorophenol and 2,4,6-trichlorophenol. In Jolley RL et al. (eds) Water Chlorination, Vol. 5, Chemistry, environmental impact and health effects. Chelsea, MI, Lewis Publishers, 1985... 

Figure 9.3 shows the degradation of pentachlorophenol (PCP), 2,4-dichlo-rophenol (2,4-DCP), 3,5-dichlorophenol (3,5-DCP), and 2,3,5-trichlorophenol (2,3,5-TCP) as reported by Jardim et al. (1997). Degradation rates as well as the toxicity of intermediates formed were investigated. Toxicity of the intermediates formed is of concern due to the fact that some of the intermediates can be more toxic than the primary compound. Intermediates formed during the oxidation of PCP and 2,4-dichlorophenol (2,4-DCP) were found to be more toxic to activated sludge than the primary compounds (Jardim et al., 1997). 

Chlorinated phenols are among the most important contaminants in the environment (aqueous systems and soils) due to their widespread use in industry and agriculture and for domestic purposes for over 50 years. It is well-known that chlorophenols are toxic at low levels. The more highly chlorinated phenols such as trichlorophenols and pentachlorophenol are also persistent. Five of the chlorophenols (2-chlorophenol, 2,4-dichlorophenol, 4-chloro-3-methylphenol, 2,4,6-trichlorophenol and pentachlorophenol) have been classified as priority pollutants by the US Environmental Protection Agency (EPA). 

As an example, 2,4-dichlorophenol (2,4-DCP) is an acidic compound with a pA"a of 7.68 and a K0Wni of 3.06 (Mackay et al. 1997). Consultation of the USEPA Ecotox database reveals a chronic reproduction toxicity NOEC value for Daphnia... 

Phenol and its compounds are ubiquitous water pollutants that are present in the effluents of a variety of chemical industries such as coal refineries, phenol manufacturing, pharmaceuticals, and industries of resin, paint, dyeing, textile, leather, petrochemical, pulp mill, etc. [9]. Phenols are known to be toxic and also, some of them, hazardous carcinogenic that can accumulate in the food chain. Phenolic compounds are a public health risk and they are heavily regulated in many countries, and must be removed from wastewater before they are discharged into the environment [10], For example, a 10 days consumption of polluted water with low concentrations (3 ppm) of 2,4-dichlorophenol can cause vomiting, paralysis, and even death in children [11, 12]. Phenol, 2-chlorophenol, and 2,4-dichlorophenol are ranked within the 250 most hazardous pollutants [13]. In addition, chlorophenols are commonly found in chlorinated water, since phenol can react with chlorine [14],... 

Aoyama H, Hojo H, Takahashi KL et al (2005) A two-generation reproductive toxicity study of 2, 4- dichlorophenol in rats. Toxicol Sci 30 59-78... 

Kobayashi S, Fukuda T, Kawaguchi K et al (1972) Chronic toxicity of 2,4-dichlorophenol in mice a simple design for checking the toxicity of residual metabolites of pesticides. J Med Soc 19 356-362... 

For example, 2,4-dichlorophenol (C6H4CI2O) mineralizes stoichiometrically according to Eq. 1-2 (Bolton and Cater, 1994). Even pollutants containing inorganic carbon such as cyanide (CN ) can be oxidized to less toxic compounds by adequate irradiation methods. 

SAFETY PROFILE Moderately toxic by ingestion, intravenous, and intraperitoneal routes. An experimental teratogen. Other experimental reproductive effects. Questionable carcinogen with experimental tumorigenic data by skin contact. Mutation data reported. Less acutely toxic than p-propiolactone. Combustible when exposed to heat or flame can react with oxidizing materials. To fight fire, use foam, alcohol foam, CO2, dry chemical. Potentially explosive reaction with butanol + 2,4-dichlorophenol + sodium hydroxide. When heated to decomposition it emits acrid and irritating fumes. 

To attain a measure of reproducibility of the MARA test repeated testing on different days using a suitable reference toxicant (3,5 dichlorophenol) was implemented. 

In comparison with the EC50 values of the aforementioned ecotoxicity tests, summarized in Table 3.1.6, the MARA test is the least sensitive to 3,5 dichlorophenol. However, this does not necessarily imply that the MARA could not potentially be used to assess the toxicity of environmental samples (Wadhia et al 2007). 

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