Neonatal co-exposure to low doses of an ortho-PCB (PCB 153) and methyl mercury exacerbate defective developmental neurobehavior in mice.

Epidemiological studies have shown a discrepancy between children in the Faeroe Islands and children in the Seychelles with regard to neuropsychological defects during early development. Both populations have a high consumption of MeHg-contaminated fish. The defective neuropsychological differences seen in children from the Faeroe Islands could be attributed to PCBs via the mother's dietary consumption of whale meat and blubber in addition to MeHg. We have previously reported that certain persistent environmental toxicants like PCBs, DDT and PBDEs can induce permanent developmental neurotoxic effects in mice when these agents are present during a critical period of the neonatal brain development. The present study investigates whether PCB 153 (an ortho-substituted PCB) can interact with MeHg to enhance developmental neurotoxic effects on spontaneous behavior and habituation. Neonatal NMRI male mice were exposed at 10 days of age to a single oral dose of one of the following doses: PCB 153 (1.4micromol/kg body weight), MeHg (0.08, 0.40, or 4.0mg/kg body weight), PCB 153 plus MeHg, or a vehicle (20% fat emulsion). Spontaneous behavior, habituation, and cognitive function were observed in 2- and 4-month-old mice. The present study demonstrates that an interaction from co-exposure to low doses of PCB 153 and MeHg enhances developmental neurotoxic effects. These effects are manifested as disrupted spontaneous behavior, lack of habituation, and reduced cognitive functions. These effects occur at doses within the same order of magnitude as reported for exposed children.