major differences between studies of mercury’s effects. The Faroe Island study found adverse health effects at 1-2 ppm in the mother’s hair, while no
effects were seen in the Seychelles Island study at an average of 6.8 ppm in the mother’s hair. Differences between study design, the
population studied, the type of
mercury-containing fish eaten (people in the Faroe Islands eat pilot whales
containing about 3 ppm mercury, 50% of
which was methylmercury), the confounding of other contaminants (PCBs were in the fish eaten in the Faroe Islands).
people have interpreted the Faroe Island study, where a measurable effect was
observed in all people in the study, to mean that effects from mercury exposure can be measured for all exposures to mercury. This is conclusion is incorrect. As noted previously, other studies have
shown no measurable effect for people with
more exposure to mercury than in the Faroe Islands.
percent of women have mercury levels in their blood between 5.8 and 58 ug/L,
within a factor of 10 of the level (58
ug/L) where adverse neurological effects have been observed.
in six (or 16%) women in the US have blood mercury levels equal to or greater
than 3.5 ug/L. This blood mercury level is lower than blood mercury
levels corresponding to exposures equal to the Reference Dose, 5.8 ug/L. Human
studies have correlated maternal blood mercury levels to health effects occurring to their fetuses. However, the researchers who believe this
correlation has not been adequately
considered are those who suspect babies are at “increased risk” of subtle
neurological damage when maternal blood
levels are 3.5 ug/L. This opinion is
not shared by all researchers.
important to point out that the term “increased risk” is not the same as
“measured adverse health effects.”
comment was that rain in Chicago contained 42 times the mercury allowed by
federal standards and 65 times the amount
“safe” for humans in Detroit. It is
inappropriate to compare the mercury in rainfall to standards for mercury in Great Lakes and water that is
safe for wildlife. These standards are
established to keep mercury in surface
waters at amounts where mercury levels in fish and other wildlife should stay below certain amounts.
In fact, the amount of mercury in rain in these cities was much lower
than the federal standard for mercury in