Report: Mercury Scare Campaigns Unfounded

Published December 1, 2005

House Resources Committee Chairman Richard W. Pombo (R-CA) and Energy and Mineral Resources Subcommittee Chairman Jim Gibbons (R-NV) released on February 16, 2005 an exhaustive paper on the science of mercury and the environment, Mercury in Perspective: Fact and Fiction About the Debate Over Mercury.
The paper is a comprehensive synopsis of the peer-reviewed research regarding the debate over regulating mercury. Said Pombo in an accompanying news release, “We have simply highlighted, in documented fashion, the most important bodies of evidence on this subject. It is clear that research must be continued, and it is very clear that the current knowledge does not support the rhetorical campaigns of special interest groups.”
Below is the final installment in a series of articles that reproduces, in condensed form, the Pombo-Gibbons report.


Ads about the health risks of mercury are, at best, filled with misinformation and half-truths. Some claim that children are being poisoned by mercury emissions from power plants that get into the water and then into the fish. As noted [earlier in the report; see the October and November 2005 issues of Environment & Climate News], this notion is scientifically unsupported. Other ads claim that 8 percent of women of childbearing age are at risk.

The original number was postulated by the National Research Council (NRC) committee in its review of the toxicological effects of methylmercury and was estimated to be around 60,000.

Not Transferred to Fetuses

Following this NRC study, the 1999-2000 National Health and Nutrition Examination Study (NHANES) released the first actual blood level measurements of mercury in U.S. women of childbearing age, which showed about 8 percent had levels equivalent to mercury ingestion doses at or above the EPA Reference Dose. The analyses of blood-mercury concentrations in maternal-aged females (16-49 years) and young children (1-5 years) participating in the 1999-2000 (NHANES) “were below levels associated with in utero effects on the fetus, or with effects in children and adults.”

None of the children participating in this study had blood-mercury concentrations above EPA’s RfD [Reference Dose].

Scare Campaigns Unfounded

Environmental fundraising groups direct … scare tactics at young mothers and their unborn and infant children. This disingenuous campaign, coupled with numerous newly issued fish advisories (due to EPA’s lowered RfD for methylmercury, better analytical techniques, and more sampling), has presented a very scary scenario for pregnant women and other Americans who would normally enjoy fish as part of a healthy diet.

In fact, some of the same groups behind the current campaign were also responsible for the Alar-Apple hoax, a well-funded campaign launched in 1989 that claimed America’s favorite natural snack food was laced with “poison”–a pesticide called Alar. However, the FDA, the EPA, the United States Department of Agriculture (USDA), the American Medical Association (AMA), and numerous other medical and agricultural experts concur that Alar never posed a health threat.

Data Contradict Fears

A recent study published by scientists from the National Institute for Minamata Disease [methylmercury poisoning] casts even more doubt on claims that regular fish consumption poses a threat to pregnant women and their unborn children. In a study conducted between 1999 and 2002, mercury hair measurements for over 8,000 Japanese individuals suggested that approximately 74 percent of females of childbearing age (15-49 years) had hair mercury levels exceeding EPA’s RfD.

This is especially interesting in light of international educational achievement scores in which Japanese children consistently score higher than children in the United States. For instance, Japanese children in the fourth grade scored significantly higher in mathematics. In the eighth grade scores, Japanese children outperformed U.S. children in mathematics and science achievement.

Overall, Japanese children are educationally outperforming U.S. children. This fact directly undercuts claims that mercury exposure in utero will negatively affect children’s IQ.

The scenario begs a series of questions for us all. If the U.S. has significantly reduced mercury emissions since 1990, why does the “problem” appear to be getting worse? What do the advisories mean, and are they valid? What is the real risk to people from exposure to methylmercury from fish consumption? Are there other health risks associated with not including fish in our diets?


The differences in methylmercury exposure levels between direct poisoning events in Japan and today’s American population are significant. Tainted fish from Minamata Bay, Japan had methylmercury concentrations as high as 40 ppm. The fish that we buy at our grocery stores range from non-detectable to 0.358 ppm, levels that are significantly less than the tainted fish from Minamata Bay and the level of FDA advisories.

American women of childbearing age and children that participated in the NHANES study had concentrations of mercury in hair that averaged just 0.2 ppm and 0.12 ppm respectively. Even the mean for the 95th percentile mercury concentration for the NHANES women’s sample is 1.4 ppm.

The lowest concentration of mercury associated with neurological problems in the Japanese people was 50 ppm in hair and 200 micrograms per liter (mcg/liter) in their blood.

Reference Dose Very Low

The FDA reviewed the available data for Japan, noting that the lowest concentration of mercury in hair samples associated with neurological disorders was 50 ppm, and established an action level of 1 ppm methylmercury in fish, or 0.4 mcg/kg/day (micrograms/kilograms of body weight/day), in 1979. In 1985, EPA established an RfD of 0.3 mcg/kg/day.

Likewise, the U.S. Agency for Toxic Substances and Disease Registry (ATSDR) has set its methylmercury minimal risk level at 0.3 mcg/kg/day and the World Health Organization (WHO) set their risk level for methylmercury at 0.5 mcg/kg/day. Japan has set a risk level of 0.48 mcg/kg/day.

Several studies have been conducted on various populations around the world that have been exposed to relatively high doses of methylmercury. The authors of the two most notable long-term epidemiological studies with several hundred cohorts designed to evaluate the subtle effects of prenatal methylmercury exposure have come to different conclusions. One group of researchers claim they observed an effect from mercury consumed in fish and pilot whale meat, and the other group saw no adverse effect from mercury consumed in fish, but rather increased benefits from eating fish.

These studies, funded by the U.S. National Institute of Environmental Health Sciences, looked at populations in the Faroe Islands and the Seychelles Islands, both known for their high intake of marine fish and/or mammals. The Seychelles and Faroe Islands studies where designed to test for subtle effects from in utero dietary exposure to methylmercury.

EPA Reduced Level Further

Children participating in the Faroe Islands study were evaluated at birth and at age seven. The Seychelles Islands group was assessed at multiple points over a twelve-year period. According to ATSDR, there were “no clinical signs of neurotoxicity or delayed developmental milestone attainment” in either group studied. However, the Faroe Islands researchers believed they observed “equivocal, subtle, functional neuropsychological effects” as some of the children involved in their study showed impaired performance on the Boston Naming Test.

Without taking into consideration the early findings of these epidemiological studies, EPA arbitrarily lowered its RfD to 0.1 mcg/kg per day in 1995.

Thus, EPA used the Faroe Island study to justify its RfD since researchers reported they had observed adverse effects from in utero exposure to methylmercury. EPA calculated a “benchmark dose lower limit” (BMDL) of 58 ppb mercury in blood (this corresponds to 12 ppm methylmercury in hair), the lowest dose where a subtle adverse effect was thought to be observed. Once the BMDL was established, EPA used a composite “uncertainty” (safety) factor of 10 to calculate the RfD of 5.8 ppb methylmercury. An RfD is the highest daily dose that the most sensitive in the population can be exposed to without experiencing an adverse effect over a lifetime of exposure.

However, EPA, supported by the NRC, rejected the Seychelles Island study because there was no adverse effect observed. They argued that without an adverse effect they could not establish a BMDL and calculate an RfD. Therefore, EPA had to rely on the Faroe Island study to justify its lowered RfD for methylmercury.

EPA Ignored Other Chemicals

There are several differences between this study and the Seychelles Islands study. The women in the Faroe Islands actually consume less fish than the women in the Seychelles. However, pilot whale is a significant component of the Faroe Islanders’ diet. The whale meat is known to have other contaminants, including PCBs and DDT, that have also been linked to neurological disorders.

The Faroe Islanders’ exposure to PCBs is 600 times higher than EPA’s RfD for Aroclor 1254 (a specific chemical in the PCB family).

Laboratory in vitro research has also shown that PCBs and methylmercury act synergistically in affecting brain tissue and chemistry.

Dr. Gary Myers, the lead researcher for the twelve-year longitudinal study conducted in the Seychelles Islands, found no negative effects from dietary exposure to methylmercury through regular fish consumption. The Seychelles population consumes an average of 12 fish meals a week and has hair methylmercury concentrations approximately ten times higher than the U.S. population.

In his July 29, 2003 testimony before the Senate Environment and Public Works Committee, Myers stated, “We do not believe that there is presently good scientific evidence that moderate fish consumption is harmful to the fetus. However, fish is an important source of protein in many countries and large numbers of mothers around the world rely on fish for proper nutrition. Good maternal nutrition is essential to the baby’s health. Additionally, there is increasing evidence that the nutrients in fish are important for brain development and perhaps for cardiac and brain function in older individuals.”

EPA Remains Adamant

EPA has not revisited its RfD, despite publication of the latest research from the Seychelles Islands in 2003. EPA’s RfD, the most restrictive in the world, has resulted in freshwater fish advisories being issued in almost every state. Unfortunately, many people find the advisories too complicated and have been frightened away from eating fish entirely.

Environmental organizations have shamelessly used these fish advisories to further their political agenda and have created the false impression that U.S. anthropogenic mercury emissions are increasing. Their ads are filled with misleading information and have contributed to a sharp decline in domestic fish consumption.

Scaring people away from consuming fish is creating a public health crisis in its own right. Fish is an important part of a healthy diet. Research has demonstrated that a diet rich in omega-3 polyunsaturated fatty acid through fish consumption has beneficial health effects for people with heart disease and various types of cancer, including breast, prostate, and endometrial. In addition, fish consumption has beneficial impacts on people suffering from Alzheimer’s disease and type-2 diabetes.

Fish’s Beneficial Effects Missed

But perhaps the most tragic aspect of this scare is the potential impact on the targeted populations–pregnant women, infants, and young children. A healthy diet that includes fish is known to significantly reduce the risks of pre-term delivery and low birth weight and has [been] shown to have positive impacts on physiological and mental development in children. A recent National Institutes of Health study found that women whose breast milk was rich in omega-3 fatty acids, of which fish is a good source, were less likely to suffer from postpartum depression.

Another recent study evaluated the association between maternal fish intake during pregnancy and children’s language and communications skills. In the assessment of 7,421 British children born in 1991 and 1992, data showed that fish intake by the mother during pregnancy and by the infant postnatally was associated with higher scores on developmental tests.


The politicization of the mercury emissions rulemaking process and the ensuing campaign launched by environmental organizations have misinformed and frightened Americans about the impacts of mercury emissions from power plants.

These claims [seek] to force an expensive, prescriptive, and currently unachievable emission reduction standard, a standard that will not produce any environmental benefit to the U.S., but promises to burden the economy and exacerbate our energy problems.

Worse, this misinformation has effectively reduced or even eliminated fish from the diets of women of childbearing age out of fear of harming their unborn children. Fish is known to be an important source of protein, omega-3 polyunsaturated acids and other important nutrients. A balanced diet that includes fish is known to significantly reduce the risks of pre-term delivery and low birth weight, and is known to have positive impacts on physiological and mental development in children.

In addition, people with heart disease and various types of cancer, Alzheimer’s disease, and type-2 diabetes realize many health benefits from including fish in their diet. Studies have consistently shown regular consumption of fish effectively reduces the risk of heart disease. With 320,000 women dying annually from heart disease, women should be encouraged to eat more fish, not less.

Most of the fish consumed in the U.S. are ocean fish harvested from many places around the world and are not impacted by domestic power-plant emissions. The average concentration of mercury in fish that Americans buy in the grocery store ranges from non-detectable to 0.358 ppm, below FDA’s action level of 1.0 ppm methylmercury.

Eliminating the fewer than 50 tons of mercury emitted from U.S. power plants will not impact mercury availability in the ocean basins. The world’s ocean basins alone contain millions of tons of naturally occurring mercury. Further, reductions in U.S. emissions are anticipated to have a minor impact on deposition within the U.S., estimates of which range from 2.7 to 3.4 percent in total U.S. mercury deposition to the environment.

Naturally occurring mercury emissions make up approximately 61 percent or more of the world mercury budget, while U.S. power plants contribute less than 1 percent of the mercury emissions.

In the U.S. mercury usage and emissions resulting from human activity have decreased significantly since 1970 and are expected to decline further.

To date, there is no commercially available, cost-effective, and reliable technology designed to consistently reduce mercury emissions on all coal types.

The mercury emissions draft rule issued by the Bush Administration is the first attempt by any administration to regulate mercury emissions from coal-fired power plants. Their preferred plan is a cap and trade program that would allow flexibility in technologies required to address mercury emissions from power plants. This approach was favored by President Clinton’s OMB [Office of Management and Budget] and even credited by former EPA Administrator Browner.

A cap and trade approach achieves another important goal. It allows the utility industry to meet new emission standards without fuel switching from coal to natural gas or from one coal type to another or causing the premature closure of existing plants.

EPA’s RfD for methylmercury should be reassessed: It is the most restrictive in the world and is based on an epidemiological study that examined a group of people exposed to multiple pollutants, primarily through the consumption of ocean-going mammals.

Results from the nine-year assessment of the Seychelles epidemiological study have been published showing no effect from exposure to methylmercury from consumption of ocean fish; and other epidemiological studies have shown positive benefits from fish consumption.

For more information …

The full text of the February 16 report by House Resources Committee Chairman Richard W. Pombo (R-CA) and Energy and Mineral Resources Subcommittee Chairman Jim Gibbons (R-NV), Mercury in Perspective: Fact and Fiction About the Debate Over Mercury, is available online at