Biological responses of the rat to polychlorinated biphenyls

Abstract

A commercial polychlorinated biphenyl mixture (PCBs), Aroclor 1242, was administered to rats po by intubation in order to determine toxic manifestations of acute and subacute ingestion. In addition, the effect of PCBs on hepatic microsomal enzyme systems in rats was evaluated. The oral, 14day LD50 was determined to be approximately 4.25 g/kg. Major toxic signs observed upon administration of high doses of PCBs included diarrhea, chromodacryorrhea, loss of body weight, unusual stance and gait, lack of response to pain stimuli, and terminal ataxia. Progressive dehydration and CNS depression appeared to be contributing factors in each fatality. Histopathologic alterations were evident only in the liver and kidneys, manifest as foci of sudanophilic vacuolation. Rats maintained on an oral dosage regimen of 100 mg/kg every other day for 3 weeks exhibited similar histopathologic changes, but no overt signs of toxicity. Serum GOT activities were elevated over controls in both the acute and subacute groups. A single ip injection (100 mg/kg) increased liver weight, total hepatic microsomal enzyme activity (measured as hydroxylation of acetanilide and N-demethylation of aminopyrine), and hepatic cytochrome P.,5,, and b5 levels. Hepatic microsomal enzyme activity remained elevated 10 days after a single dose of PCBs, suggesting that PCBs may play an important role in altering biologic responses of mammals subjected to environmental chemical stress. Polychlorinated biphenyls (PCBs) have experienced widespread industrial usage and are now widely distributed throughout the environment (Gustafson, 1970; Peakall and Lincer, 1970). These compounds have been found in the livers of dying pelagic birds (Bourne and Mead, 1969), in fish, mussels, and birds (Koeman et al., 1969), and even in human adipose tissues (Biros et al., 1970). Humans have been inadvertently exposed to PCBs in several instances, including ingestion of PCB-contaminated rice oil in Japan (Kuratsune, 1969), and poultry products in the United States (Pichirallo, 1971). Data on the precise chemical composition and the toxicity of PCBs is at present incomplete. Commercial PCB products are known to consist of mixtures of isomers, differing from one another in the degree of chlorination. Vos and co-workers (1970) reported 2 such products, Clophen and Phenoclor, to be contaminated by trace amounts of chlorinated naphthalenes and highly poisonous chlorinated dibenzofurans. Chlorinated dibenzofurans have been implicated in the toxic action of Clophen and Phenoclor,

Toxicity and persistence of PCB homologs and isomers in the avian system

“…Koch etal. (1972)proposed that ATPase inhibition may be another important effect of PCBs on fish tissue, while Bruckner et al (1973) concurred with Litterst et al (1972) that alterations in tile rate of metabolism caused by PCBs may affect the biological responses of mammals to drugs and environmental stress.…”

Associations between Organochlorine Contaminant Concentrations and Clinical Health Parameters in Loggerhead Sea Turtles from North Carolina, USA

“…For example, in humans, an elevation in blood aspartate aminotransferase (AST) activity is a sensitive indicator of liver damage due to PCB exposure (Feeley 1995). Likewise, incidences of liver necrosis and blood AST activity were both increased in rats and American kestrels exposed to PCBs (Bruckner et al 1973; Hoffman et al 1996). …”

The Role of Domoic Acid in Abortion and Premature Parturition of California Sea Lions (Zalophus Californianus) on San Miguel Island, California

“…Nonetheless, organochlorines such as PCBs and DDTs persist in this region, high levels are still observed in sea lions (Ylitalo et al, 2005;Greig et al, 2007), and experimental exposure studies have shown these chemicals to affect both immune function and reproductive success of pinnipeds (Reijnders, 1986;Ross et al, 1996). These chemicals have also caused reproductive failure in both experimental models and other wildlife species (Hart et al, 1971;Bruckner et al, 1973;Fry, 1995). Sea lions may accumulate these contaminants via prey since high levels of contaminants have been measured in demersal fish species (Zeng and Tran, 2002), as well as through transplacental transfer and lactation .…”