|There are 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
|Some 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.
|Six 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.
|About one 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
|It is important to point
out that the term “increased risk” is not the same as “measured adverse
|One 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 drinking