Exposure to mercury in the diet of pregnant women can delay children's neurological development.

This finding of a recent study of almost 1000 children born in the Faroe islands, where mothers eat fish and pilot whale meat containing methylmercury, has implications for women with large amalgam fillings.

According to dentist Peter Lawson of the University of Surrey, mercury toxins can cross the placenta, increasing the concentration in the fetus by 40 per cent more than the concentration in the mother Maternal hair and fetal blood samples collected at birth detected in utero mercury exposure. These showed a direct correlation between mercury levels and children's future neurological defects. Nine out of 20 tests on seven year olds showed both neurological and behavioural deficiencies. A doubling in mercury exposure in utero has been found to cause a developmental delay of about two months for various functions.

Although the latest research did not concern amalgam fillings, this latest research should be of concern to pregnant women. In early scientific studies, mercury fillings have been proven to leak amalgam vapours from the mouth to various body' parts and to cross the placenta but no one has been sure if it caused actual damage to the fetus.

This research may mean that a large body load of mercury in the mother can cause neurological damage in her child (The Lancet, 1997; 350: 1453).