Session Title :

Health effects of mercury: the Child Cohort Studies in the Faroe Islands

Synopsis

The session will present the main findings of studies conducted in the Faroe Islands since the mid eighties in order to investigate the negative impact of dietary organic mercury on public health.

Description

Toxicological evidence suggests that humans are much more vulnerable to adverse effects from exposures to pollutants that occur during development, i.e., prenatally or in early childhood. However, the adverse effects may not be immediately apparent and often are expressed fully only when physiological functions have matured. Accordingly, research in environmental epidemiology now emphasizes prospective research, in this case based on birth cohorts. Given the advantages of conducting such research in the Faroe Islands, we have therefore generated five birth cohorts. In addition, we have used available records on whaling during the past century to clarify prenatal methylmercury exposure of elderly people on the basis of availability.

Mercury from pilot whale meat adversely affects the foetal development of the nervous system. Decrements in attention, language, verbal memory, and, to a lesser extent, in motor speed and visuospatial function, were associated with the mercury exposure. This association was still evident after the exclusion of high exposure subjects. As an objective neurophysiological parameter, delays on brainstem auditory-evoked potentials were also associated with increased exposures. Exposure-related decrease in heart rate variability and a tendency of increased blood pressure were also found. Findings were replicated at age 14 years, when cohort members were examined by comparable methods. Adjustment for polychlorinated biphenyls exposure did not materially affect the mercury effects.

In this session we will present and discuss our findings, i.e. methylmercury exposure and its sources and neurotoxic effects on children. Furthermore we will discuss confounding problems and statistical modeling.