Human health consequences of consumption of fish contaminated with organochlorine compounds

Abstract

Residue-forming organic contaminants of anthropogenic origin have become ubiquitous, distributed throughout the global environment. Bioaccumulation of these contaminants in the aquatic ecosystem frequently contributes to elevated concentrations of organic substances in fish, exceeding recommended guidelines for human consumption. Although often surrounded by considerable controversy, the effects of acute human exposure to toxic organic substances are reasonably well-documented, chiefly as a result of occupational exposure or catastrophic accident. Less well-understood are the effects of small, repeated, or chronic additions of these materials on the health of humans. This study reports efforts to understand human exposure to organochlorine compounds resulting from consumption of fish. Human experience of exposure to polychlorinated biphenyls (PCBs) is analyzed in the light of data acquired from extensive epidemiological studies in the North American Great Lakes of two marched cohorts of exposed individuals consisting of: (a) sports fishermen, and (b) mothers and their newborn infants. These groups were chronically exposed to significant quantities of PCBs via consumption of freshwater fish from Lake Michigan. Health effects in chronically exposed sports fishermen included an increase of circulating blood titer of contaminant in direct relation to quantities of fish consumed and duration of exposure. Maternal health effects observed among individuals in the highly exposed category included tendencies toward increases in anemia, edema, and susceptibility to infectious disease. Transplacental transmission of the contaminant was confirmed, along with subsequent exposure of infants, both in utero and postpartum, via maternal milk. Effects observed among infants born to mothers in the high fish-consumption categories include delays in developmental maturation at birth. These infants were smaller in physical size, had reduced head circumferences, altered lability of state, increased startle reflexes, and were classified by attending physicians within the ‘worrisome’ neonatal category. Subsequent testing of these infants at the age of seven months demonstrated substantial alterations in fixation to novelty. The tendency to respond to a new stimulus decreased in direct proportion to the level of maternal exposure to contaminants in fish consumed, suggesting a more than ten percent decline in visual recognition memory. This observation suggests an effect of contaminants upon the centers of higher integration in infants secondarily exposed via maternal circulation.