Subchronic oral toxicity in guinea pigs of soot from a polychlorinated biphenyl-containing transformer fire

Application of clinical laboratory measurements to issues of environmental health

Monitoring of biochemical constituents in serum is an important component in revealing potential toxicity in humans and experimental animals due to exposure to a variety of xenobiotic agents. The relative toxicity of pure compounds, usually at large doses, has helped elucidate the mode of action of these compounds and their relative risk. However, most actual cases of environmental exposure present an extensive range of components and the potential for synergistic or inhibitory interactions. In this paper we review two such environmental cases: The Love Canal chemical dump site in Niagara Falls, NY, and the transformer fire at the State Office Building in Binghamton, NY. We focus on the clinical laboratory measurements obtained in these studies (including serum glucose, triglycerides, aspartate aminotransferase, alanine aminotransferase, alkaline phosphatase, gamma-glutamyltransferase, lactate dehydrogenase, sodium and potassium), their usefulness, limitations, and application to such cases. Significant alterations in serum triglyceride and alanine aminotransferase levels were found in guinea pigs due to exposure to dioxins. These two tests were useful in estimating the 'equivalent' concentration of 2,3,7,8-tetrachlorodibenzo-p-dioxin in complex chemical mixtures.

Dioxins and the Ah receptor

Despite continuing controversies related to public policy, information on the molecular biology of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) has advanced significantly over the past decade. Current understanding of the biological mechanisms of TCDD action is based upon the interactions of TCDD with a genetically expressed cytosolic macromolecule that functions as a receptor in many cells across many species. The Ah receptor recognizes TCDD and structurally similar molecules and serves as the transducing step whereby TCDD alters gene expression through the association of the TCDD:receptor complex with specific TCDD-responsive elements on the genome. Understanding these molecular events and their relevance to the organ-level manifestations of TCDD toxicity may be critical to formulating scientifically based assessments of the risk of TCDD exposure.

Pathology of stranded beluga whales (Delphinapterus leucas) from the St. Lawrence Estuary, Québec, Canada

From June 1983 to May 1986, thirteen carcasses of stranded beluga whales from a polluted area of the St. Lawrence River, Canada were necropsied. High performance liquid chromatography was performed on the brains of three other animals to determine concentrations of benzo a pyrene (BaP). Two juvenile animals had severe multisystemic lesions one of which, a severe necrotizing dermatitis, was associated with a Herpesvirus-like particle. Four adults had five varieties of tumours. An adult had a systemic nocardiosis and a juvenile was affected ty a non 0:1 Vibrio cholerae septicemia. High concentrations of BaP adducts were found in the brains which were analyzed. Occurrence of BaP adducts in the brain of three whales of this population coincides with the high incidence of tumours. This and the previous finding of high concentrations of organochlorine in the tissues of these animals suggest an important role of industrial contaminants in the recent decrease of this population.

Liver morphology in guinea pigs fed pyrolysis products of a polychlorinated biphenyl transformer fluid continuously for 90 days

After a fire involving a transformer, the State Office Building in Binghamton, New York, was contaminated with soot containing polychlorinated biphenyls, biphenylenes, naphthalenes, dioxins, and dibenzofurans. The toxicity of the soot and its effect on liver morphology after prolonged (subchronic) exposure were determined for both sexes of Hartley guinea pigs, which were fed soot continuously for 90 days. By light microscopy the observed alterations of the liver were predominantly centrilobular; they included hepatocyte hypertrophy, steatosis, increased glycogen and iron, focal necrosis, and bile duct proliferation with fibrosis. Cytoplasmic vacuoles and acidophilic hyalin-like bodies were observed. Electron microscopy of hepatocytes showed proliferated smooth endoplasmic reticulum (SER), cytoplasmic vacuoles, concentric membrane arrays (CMAs), glycogen bodies, and microdroplets of fat, often without limiting membranes. The vacuoles frequently contained membrane fragments and had a halo-like periphery composed of proliferated membranes. Cell debris, membrane fragments, and small CMAs were observed in the sinusoids. Membrane fragments were also observed in the bile canaliculi and bile ducts. Intoxicated bile duct cells contained more cytoplasmic myelin whorls and altered mitochondria. In contrast to the previously reported study of a single dose, these liver alterations showed a strong dose dependence, emphasizing the importance of time and method of administration. The cytoplasmic vacuoles, which were not pronounced in the previous study, are here a prominent alteration, probably originating from outpouchings of canaliculi and sinusoidal membranes. A hypothesis for the mechanism of hepatocyte detoxification based on the proliferated SER and ejection of membrane fragments is proposed.