The EPA reference dose (RfD) is defined as the amount of mercury a
person, including sensitive subpopulations, can be exposed to on a
daily basis over a lifetime without appreciable risk of effects.
The EPA RfD is 0.1 µg mercury per kg body weight per
day. When using the mercury calculator at GotMercury.Org, this value
(adjusted for a week of exposure) is the value to which your mercury
levels are being compared.
This level corresponds to a blood mercury level of 5.8
ug/L or 5.8 parts per billion (ppb) mercury. Blood mercury levels below
this value are considered to be without appreciable risk by the EPA.
For hair, the mercury level that corresponds to the RfD is 1 part per million (ppm).
A study by Turtle Island Restoration Network (TIRN) of mercury levels in
swordfish found that 68% of the swordfish samples were above the FDA
Action Level of 1 part per million mercury and 16% were over 2 parts
per million (twice the FDA's Action Level). The average mercury
concentration was 1.38 parts per million, which is 38% higher than the
FDA Action Level.
The FDA has set an "action level" of 1 part per
million (ppm) for seafood. Ironically, the FDA fails to take action
when fish in grocery stores or restaurants exceed the "action level"
In 2004, a study found that the number of infants that
are potentially exposed to dangerous levels of mercury in the womb was
630,000 children in the U.S. annually. This was double the previous
estimates and was determined from mercury levels in umbilical cords,
which contain mercury levels 1.7 times higher than those of the
mother's blood level. Based upon this data, far more babies are being
exposed to the reference dose than previously thought.