|IDENTIFICATION AND USE: 2, 4, 5-Trichlorophenol (2, 4, 5-TCP) comes in the form of colorless needles from alcohols or in gray flakes. It was formerly used as a fungicide, bactericide, biocide; intermediate in production of herbicides, in adhesives as a preservative in polyvinyl acetate emulsions; in the automotive industry to preserve rubber gaskets; in textiles to preserve emulsions used in the rayon industry; in cooling towers; paper and pulp mill systems; hide and leather processing; on swimming pool related surfaces; sickroom equipment; and food processing plants and equipment. 2,4,5-TCP is not registered for current use in the U.S., but approved pesticide uses may change periodically and so federal, state and local authorities must be consulted for currently approved uses. HUMAN EXPOSURE AND TOXICITY: In the eye, trichlorophenols induce conjunctival irritation and sometimes corneal injury and iritis. dusts are irritating to nose and pharynx. Dermatoses, including photoallergic contact dermatitis, have been reported in man after exposure to 2,4,5-TCP, these include papulofollicular lesions, comedones, sebaceous cysts, and marked hyperkeratosis. During the clean-up following explosions during 2,4,5-TCP manufacture, chloracne was generally severe, and many cases had some signs or symptoms or lab abnormalities indicating systemic toxicity. Systemic effects of trichlorophenols presumably resemble phenol. Symptoms from upper airways and chest were more common among 7 subjects exposed to trichlorophenol than in control subjects (60% and 10%). The findings suggest an irritating effect on the lung of trichlorophenol, and it cannot be excluded that long-term exposure may produce pulmonary fibrosis. 2,4,5-TCP has not been shown to have a teratogenic effect. In a study of workers exposed to 2, 4, 5-TCP 10 years earlier, neither chromosomal aberrations nor sister chromatid exchanges were observed. Exposure to chlorophenols has been shown to cause an increased incidence of carcinomas including a significant trend observed for total gastrointestinal system cancer related to work in 2,4,5-TCP and 2-(2,4,5-trichlorophenoxy)-propionic-acid production areas. ANIMAL STUDIES: Restlessness and increased rate of respiration followed by rapidly developing motor weakness. tremors, clonic convulsions (induced by noise or touch), dyspnea, and coma continue until death. D-amino acid oxidase and heart muscle flavoproteins were inhibited by 2,4,5-TCP in vitro. In rat and rabbit hyperpyrexia from injections of trichlorophenols has been reported. In a 98-day feeding study in rats, 0.3 g and 1 g/kg body weight/day doses of 2,4,5-trichlorophenol retarded weight gain and caused diuresis, mild centrilobular changes in the liver, moderate degenerative changes in the convoluted tubules of the kidneys and early proliferative changes in the kidney interstitial tissue. Slight proliferation of bile ducts and early portal cirrhosis were also observed. The severity of effects was dose related. No significant effects were observed with doses of 100 mg/kg body weight/day (0.1% in diet) or less. 2,4,5-TCP given by gavage to pregnant mice in single doses of 800-900 mg/kg or multiple doses of 250-300 mg/kg caused no significant fetal effects and the results obtained in Hydra attenuata and whole embryo culture assays suggest that chlorinated phenols are not potent teratogens. Hydra attenuata and whole embryo culture studies demonstrated a linear relationship between toxicity and the degree of chlorine substitution with pentachlorophenol > 2,3,4,5-tetrachlorophenol > 2,3,5-TCP > 3,5-dichlorophenol > 4-chlorophenol > phenol. The developmental hazard index A/D ratios from the Hydra attenuata assay were approximately 1 for all of the chemicals tested. Findings from the whole embryo culture assay indicated similar results based on growth, gross morphology, and DNA and protein content of embryos. The results obtained in the Hydra attenuata and whole embryo culture assays suggest that the chlorinated phenols are not potent teratogens. 3-Chlorophenol, 4-chlorophenol, 2,3,6-, 2,4,5-, 2,4,6-TCP, 4-chloro-2-methylphenol, and 4-chloro-3-methylphenol produced mutagenic activity at least in one tester strain (TA97, TA98, TA100, or TA104) in the Ames test. The induction of forward mutation to 6-thioguanine resistance in V79 Chinese hamster cells by six different chlorophenols was examined. Each of the chlorophenols tested reduced the plating efficiency in a dose dependent manner including 2,4,5-TCP at doses of 6.25 to 50 ug/mL. This cytotoxic effect can be attributed to the ability of pentachlorophenol and other chlorophenols to inhibit oxidative phosphorylation. ECOTOXICITY STUDIES: Chlorinated phenols represent a major component of hazardous oily and wood-preserving wastes that are widely distributed in chemical dumpsites throughout the United States. The acute toxicity of some chlorinated phenols, catechols, and cresols, incl 2,4,5-trichlorophenol, to trout was determined. The lowest lethal concn of the cmpd studied was 0.20 ppm caused by pentachlorophenols, tetrachlorophenols, and trichlorophenols. The residue of chlorophenol in larval tissue was measured and the correlation to the concentration on larval mortality was highly significant in the growth test. In the emergence test, however, mortality was low (3-13%) at all concentrations. 2, 4, 5-TCP did not affect larval growth at the concentrations used. The concentration of 2, 4, 5-TCP in the whole larvae after the 10-day exposure was proportional to sediment concentration.