Health implications for Faroe islanders of heavy metals and PCBs from pilot whales.

In the Faroe Islands marine food constitutes a considerable part of the diet. In addition to fish, both meat and blubber from pilot whales are included in the diet. Muscle tissue of pilot whales caught in the Faroe Islands contains an average mercury concentration of 3.3 micrograms/g (16 nmol/g), about half of which is methylmercury. In some years an evenly distributed annual catch of pilot whales would make the average dietary intake of mercury close to an excess of the Provisional Temporary Weekly Intake of 0.3 mg recommended by WHO. In one out of eight consecutive births, the mercury concentration in maternal hair exceeded a limit of 10 micrograms/g where a risk of neurobehavioral dysfunction in the child may occur; the maximum was 39.1 micrograms/g. Mercury concentrations in umbilical cord blood showed a similar distribution with a maximum of 351 micrograms/l. The large variation in mercury exposure is associated with differences in the frequency of whale dinners. The average PCB concentration in pilot whale blubber is very high, i.e. about 30 micrograms/g. With an estimated daily consumption of 7 g of blubber, the average daily PCB intake could therefore exceed 200 micrograms, i.e. close to the Acceptable Daily Intake. In Scandinavia, the average daily PCB intake is about 15-20 micrograms. To obtain an improved scientific basis for public health action, two major prospective studies have been initiated. A birth cohort of 1000 children has been examined at approximately 7 years of age for neurobehavioral dysfunctions associated with prenatal exposure to mercury and PCB. Preliminary analyses of the data show that several neurobehavioral tests are associated with mercury exposure parameters. With emphasis on prenatal exposures to PCB, another cohort has been generated during 1994-95, and this cohort will be followed closely during the next years.