Effects of pentachlorophenol and 2,4,6-trichlorophenol on the disposition of sulfobromophthalein and respiration of isolated liver cells

Subchronic Toxicity Studies of 2,4,6-Trichlorophenol in Sprague-Dawley Rats

2,4,6-Trichlorophenol (TCP) has been found in drinking water as a result of its use as a fungicide and due to its inadvertent production in the water purification process. This study was conducted since information on the toxicity from repeated ingestion was inadequate. Male and female Sprague-Dawley rats were gavaged with TCP administered in corn oil (2 ml/kg body weight) for 90 consecutive days at dose levels of 0, 80, 240, and 720 mg/kg per day. Treatment-related effects were observed at the highest dose (720 mg/kg/day) and consisted of salivation, urine stains on the fur, increase in absolute and relative weights of the kidneys, liver, adrenal glands, and testes. At this dose, increases were seen in serum protein, albumin, and alanine aminotransferase (ALT), with a decrease in urinary pH. Some effects observed at 240 mg/kg per day were an increase in the absolute and relative weights of the liver and adrenal glands in females, relative liver weights in males, and an increase in serum albumin in males. No treatment-related effects were observed at 80 mg/kg per day. No mortality or significant effects were observed at any dose level for body weight, food consumption, ophthalmic lesions, hematology, gross pathology, or histopathology. Based on clinical chemistry and organ weight changes, it appears that the liver, kidney, and adrenal glands were target organs for systemic toxicity to TCP in this study, although this was not correlated with histopathology lesions. It was concluded that 240 mg/kg/day represents a lowest observed adverse effect level (LOAEL), although the toxic effects were minimal. The no observed adverse effect level (NOAEL) for subchronic exposure to TCP by the oral route was 80 mg/kg per day.

Short-term effects of chlorophenols on the function and viability of primary cultured rat hepatocytes

Primary cultured rat hepatocytes were used as an experimental model to detect adverse effects of five chlorophenols (CP) in vitro (penta-CP, 2,3,4,5-tetra-CP, 2,4,5,-tri-CP, 2,4-di-CP, and 4-mono-CP). Monolayer cultures were exposed to the test compounds for 1 h, and concentration-response curves were established with respect to the effects on phase I and phase II metabolism of 7-ethoxycoumarin (7-EC) and on cellular ATP content. All CP tested inhibited the O-dealkylation of 7-EC, with half-maximum effective concentrations (EC50) ranging from about 36 microM for the three highest chlorinated phenols to 215 microM for 4-mono-CP, which proved to be least effective. The subsequent conjugation of the primary metabolite 7-hydroxycoumarin was even more sensitive towards CP exposure than the O-deethylation process. The concentrations which reduced the percentage of conjugated metabolite to 50% of the respective control cultures ranged from 7 microM for penta-CP to 48 microM for 4-mono-CP. Treatment of cultured hepatocytes with CP additionally resulted in a depletion of cellular ATP at EC50 concentrations ranging from 6 microM for penta-CP to 1330 microM for 4-mono-CP. Cellular viability, as measured by the leakage of lactate dehydrogenase from the cells, was not affected by any of the CP within the 1-h exposure period.

In vitro screens from CNS, liver and kidney for systemic toxicity

The development and evaluation of in vitro systems from target organs for preliminary assessments of the potential for systemic toxic effects has been receiving increased attention. This review presents a synopsis of progress made in developing toxicity screens for three common target organs and identifies further work needed for more complete validation.

Occupational exposure to hexachlorocyclohexane. VI. Metabolism of gamma-hexachlorocyclohexane in man

Metabolism of gamma-Hexachlorocyclohexane (HCH) was studied examining 21 workers producing this insecticide. Using gas chromatography in combination with ECD and mass spectrometry 14 mono-, di-, tri- and tetrachlorophenols were identified in the urine samples of the workers. Seven dihydroxychlorobenzenes of still unknown configuration were detected by mass spectrometry. Ten of the more abundant metabolites, di-, tri- and tetrachlorophenols were determined quantitatively in all urine samples. 2,4,6-; 2,3,5- and 2,4,5-trichlorophenol turned out to be the main metabolites of gamma-HCH. They were excreted in nearly equal quantities. On account of their potential liver toxicity, the determination of chlorophenols in urine should be part of a biological monitoring program of HCH-exposed persons.

Effect of decreased glucuronidation and sulfation on covalent binding of naphthalene in isolated rat hepatocytes

Isolated hepatocytes metabolize naphthalene to water soluble compounds. During metabolism, reactive intermediates are formed which bind irreversibly to cellular macromolecules. When naphthalene concentrations in the incubation were raised from 400 to 1200 microM the formation of water soluble metabolites of the aromatic hydrocarbon increased about twice from 16 to 37 nmol/mg cellular protein X h, whereas covalent binding increased up to 10 times. This suggests a qualitative shift in the metabolic pattern of naphthalene probably due to the exhaustion of inactivating pathways. Inhibition of glucuronidation and sulfation -- 2 reactions involved in the metabolism of naphthalene -- did not change the amount of water soluble metabolites but dramatically increased binding.