The US Environmental Protection Agency (EPA) estimated that one in six (630,000) babies born in the US in the years 1999 and 2000 already had unsafe levels of mercury in their blood. The estimate was much higher than before because new research had shown that, contrary to current belief, mercury levels in the baby’s umbilical cord were not the same as in the mother’s blood, but usually 70% higher. A pregnant woman with a ‘safe’ level of, say, 3.5 parts per billion will give birth to a baby with a level way over the supposed ‘safe level’ of 5.8 parts per billion.

Agency biochemist Kathryn Mahaffey stated that most of the mercury in newborns comes from fish eaten by their mothers. Data gathered by the US Centers for Disease Control showed that women who had eaten fish at least nine times in a month had seven times as much mercury in their blood as women who had not eaten fish during the previous month.

Ed.- (i) Two studies by researchers from the Harvard School of Public Health and institutions in Japan, Denmark and the Faroe Islands found that:

• high levels of mercury passed from pregnant mothers to their unborn babies causing irreversible impairment to specific brain functions in children. The researchers knew that the babies had gained their mercury contamination while in the womb because prenatal and postnatal mercury exposure appear to affect different areas of the brain. Even supposedly ‘safe’ levels of mercury caused lasting changes in brain function [1]

• the neurological changes are also linked to decreased nervous system control of the heart function. At higher mercury exposures, the children were less capable of maintaining the normal variability of the heart rate necessary to secure proper oxygen supply to the body [2]

(ii) The EPA says that the largest sources of environmental mercury contamination in the US are coal-fired power plants, whose annual atmospheric emissions contain 48 tons of mercury, much of which drifts into lakes, streams and the ocean, where it enters the food chain, including fish eaten by people.

The Bush Administration has recently proposed a 'pollution credits trading system' similar to the Kyoto Protocol's carbon credits system. Under the proposal, rather than reduce their toxic emissions, dirty factories would be able to buy pollution credits from super-clean factories which did not need the credits they had been allocated. The proposal has been widely criticised because it would allow the continuation of, for instance, mercury 'hot spots' for much longer.

(iii) According to a 1991 WHO report, amalgam fillings constitute the major human exposure to mercury. [3] The UK and US Governments, keen to blame sources of mercury as far away as possible from their approved dental procedures, put the emphasis on industrial pollution.