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High levels of mercury in newborns likely from mothers eating contaminated fish


Mercury in humans is often from eating
contaminated fish

Methylmercury is one of the strongest neurotoxins especially harmfull during the development of the brain. Therefore, even small amounts of mercury can hurt infants’ developing brain and nervous system. Unfortunately, methylmercury, the mercury species present in fish, can be absorbed from food nearly quantitively and can easily pass from a mother to her unborn child through the placenta. Fish gets contaminated with mercury by deposition of atmospheric pollution up to high contamination levels via bioaccumulation and biomagnification along the trophic levels of the food chain.

The new study:
A new study, conducted by the Minnesota Department of Health from 2008 to 2010, tested 1,465 newborns living in Michigan, Wisconsin and Minnesota for mercury. A wide range of total mercury concentrations was measured in blood spots from newborns in the US Lake Superior Basin. Forty three percent of the specimens were below the method detection limit (MDL) of 0.7 µg/l. Results between the MDL and the report level (RL) are reported by the MDH PHL as estimated. Estimated values were included in the data analysis. Given the high percentage of non-detects, median (50th percentile) values are reported. Eight percent of the specimens analyzed were above 5.8 µg/l; the US EPA Reference Dose (RfD) for methylmercury. Mercury concentrations in about one percent (14 of 1465) of specimens were above 58 µg/l; the Benchmark Dose Limit (BMDL) used by EPA in developing the RfD. The maximum concentration measured was 211 µg/l.

Babies born in warm months were more likely to have higher levels, which, when coupled with the methymercury findings, suggest that fish consumption is the culprit. Newborns that tested above EPA established mercury limits were broken down by state:

  •     No Michigan newborns
  •     3 percent of Wisconsin newborns
  •     10 percent of Minnesota newborns

Minnesotans report eating more locally caught fish, which could explain this difference.

Comparison with earlier data is not easy, since published data on levels of mercury in newborn blood is rare (see list of related studies below). However, the percentage of participants with mercury levels above the RfD in this study is similar to that for women of childbearing age who participated in National Health and Nutrition Examination Survey (NHANES). The results show that mercury exposure is a problem for some in this area. Although a direct link to fish consumption cannot be established from this study, the demonstrated seasonality of exposure provides suggestive evidence of that link. The researchers belive that these results provide fish advisory programs stronger evidence for the need to talk with women of childbearing age about reducing mercury exposure. They study concludes that increased public outreach and communication is needed to ensure the public has information that promotes eating fish that are low in mercury.

Source: Adapted from an article that first appeared on the Great Lakes Echo

The new study:
Patricia McCann, Mercury Levels in Blood from Newborns in the Lake Superior Basin, Final Report GLNPO ID 2007-942, November 2011, Minnesota Department of Health

Related studies (newest first):

  K.R. Mahaffey, R.P. Clickner, R.A. Jeffries, Adult women’s blood mercury concentrations vary regionally in the United States: association with patterns of fish consumption (NHANES 1999–2004), Environ. Health Perspect., 117/1 (2009) 47-53. doi: 10.1289/ehp.11674

Lubica Palkovicova, Monika Ursinyova, Vlasta Masanova, Zhiwei Yu and Irva Hertz-Picciotto, Maternal amalgam dental fillings as the source of mercury exposure in developing fetus and newborn, J. Expo. Sci. Environ. Epidemiol., 18 (2008)326–331; doi: 10.1038/sj.jes.7500606

K. Murata, M. Dakeishi, M. Shimada, H. Sato, Usefulness of umbilical cord mercury concentrations as biomarkers of fetal exposure to methylmercury, Nippon Eiseigaku Zasshi 62/4 (2007) 949-959. doi:10.1265/jjh.62.949

Elisabeth Oliveira Santos, Iracina Maura de Jesus, Volney de Magalhães Câmara, Edílson da Silva Brabo, Maria Izabel de Jesus, Kleber Freitas Fayal, Carmen Ildes Rodrigues Fróes Asmuset, Correlation between blood mercury levels in mothers and newborns in Itaituba, Pará State, Brazil, Cad. Saúde Pública, 23/S.4 (2007) S622-S629. doi: 10.1590/S0102-311X2007001600022

A.H. Stern, A revised probabilistic estimate of the maternal methyl mercury intake dose corresponding to a measured cord blood mercury concentration, Environ. Health Perspect, 113/2 (2005) 155-163. doi: 10.1289/ehp.7417

A.H. Stern, A.E. Smith, An assessment of the cord blood:maternal blood methylmercury ratio: implications for risk assessment, Environ. Health Perspect., 111/12 (2003) 1465-1470. doi: 10.1289/ehp.6187

K. Ask, A. Åkesson, M. Berglund, M. Vahter, Inorganic Mercury and Methylmercury in Placentas of Swedish Women, Environ. Health Persp., 110/5 (2002) 523-526. doi: 10.1289/ehp.02110523

P. Schramel, S. Hasse und J. Ovcar-Pavlu, Selenium, cadmium, lead, and mercury concentrations in human breast milk, in placenta, maternal blood, and the blood of the newborn, Biol. Trace Elem. Res., 15/1 (1988) 111-124, DOI: 10.1007/BF02990130

H. Tsuchiya, K Mitani, K. Kodama, T. Nakata, Placental Transfer of Heavy Metals in Normal Pregnant Japanese Women, Arch. Environ. Health,  39/1 (1984) 11-17. doi:

Analytical techniques used in this study

Inductively coupled plasma mass spectrometry

Related information

Minnesota Department of Health: Mercury in Newborns in the Lake Superior Basin 
Minnesota Department of Health: Guidelines for safe fish consumption for pregnant women, women planning pregnancy and children under age 15, as well as the general public

Related EVISA Resources

Link database: Mercury pollution
Link database: Mercury toxicity
Link database: Dietary mercury exposure
Link database: Mercury in fish

Related EVISA News (newest first)

December 21, 2011: Tracing the source of mercury pollution
December 20, 2011: Mercury is converted to oxidized species in the upper atmosphere facilitating its entrance into the food chain
October 15, 2011: Mercury pollution in the Great Lakes region -- nearly forgotten, but not gone
August 21, 2009: USGS Study Reveals Mercury Contamination in Fish Nationwide
February, 11, 2009: Mercury in Fish is a Global Health Concern
March 11, 2007: Methylmercury contamination of fish warrants worldwide public warning
February 18, 2007: New research results suggest that mercury hotspots in the northeastern US are home made
October 9, 2006: Linking atmospheric mercury to methylmercury in fish
August 16, 2006: Mercury pollution threatens health worldwide, scientists say
February 17, 2006:  Study shows link between clear lakes and methylmercury contamination in fish
February 9, 2006: Study show high levels of mercury in women related to fish consumption
September 13, 2005: Regulating Mercury Emissions from Power Plants: Will It Protect Our Health?
August 29, 2005: Is methyl mercury limiting the delight of seafood ? - To answer this question is a challenge for elemental speciation analysis
April 27th, 2004: FDA/EPA recommends pregnant women to restrict their fish consumption because of methylmercury content

last time modified: March 1, 2012


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