Skip to main page content
Access keys NCBI Homepage MyNCBI Homepage Main Content Main Navigation
. 2012 Jun;120(6):799-806.
doi: 10.1289/ehp.1104494. Epub 2012 Jan 24.

Evidence on the Human Health Effects of Low-Level Methylmercury Exposure

Free PMC article

Evidence on the Human Health Effects of Low-Level Methylmercury Exposure

Margaret R Karagas et al. Environ Health Perspect. .
Free PMC article


Background: Methylmercury (MeHg) is a known neuro-toxicant. Emerging evidence indicates it may have adverse effects on the neuro-logic and other body systems at common low levels of exposure. Impacts of MeHg exposure could vary by individual susceptibility or be confounded by beneficial nutrients in fish containing MeHg. Despite its global relevance, synthesis of the available literature on low-level MeHg exposure has been limited.

Objectives: We undertook a synthesis of the current knowledge on the human health effects of low-level MeHg exposure to provide a basis for future research efforts, risk assessment, and exposure remediation policies worldwide.

Data sources and extraction: We reviewed the published literature for original human epidemiologic research articles that reported a direct biomarker of mercury exposure. To focus on high-quality studies and those specifically on low mercury exposure, we excluded case series, as well as studies of populations with unusually high fish consumption (e.g., the Seychelles), marine mammal consumption (e.g., the Faroe Islands, circumpolar, and other indigenous populations), or consumption of highly contaminated fish (e.g., gold-mining regions in the Amazon).

Data synthesis: Recent evidence raises the possibility of effects of low-level MeHg exposure on fetal growth among susceptible subgroups and on infant growth in the first 2 years of life. Low-level effects of MeHg on neuro-logic outcomes may differ by age, sex, and timing of exposure. No clear pattern has been observed for cardio-vascular disease (CVD) risk across populations or for specific CVD end points. For the few studies evaluating immunologic effects associated with MeHg, results have been inconsistent.

Conclusions: Studies targeted at identifying potential mechanisms of low-level MeHg effects and characterizing individual susceptibility, sexual dimorphism, and non-linearity in dose response would help guide future prevention, policy, and regulatory efforts surrounding MeHg exposure.

Conflict of interest statement

The opinions presented here are those of the authors and do not necessarily reflect the policies of the U.S. EPA.

The authors declare they have no actual or potential competing financial interests.

Comment in

Similar articles

See all similar articles

Cited by 138 articles

See all "Cited by" articles


    1. Alves MF, Fraiji NA, Barbosa AC, De Lima DS, Souza JR, Dorea JG, et al. Fish consumption, mercury exposure and serum antinuclear antibody in Amazonians. Int J Environ Health Res. 2006;16(4):255–262. - PubMed
    1. Axelrad DA, Bellinger DC, Ryan LM, Woodruff TJ. Dose–response relationship of prenatal mercury exposure and IQ: an integrative analysis of epidemiologic data. Environ Health Perspect. 2007;115:609–615. - PMC - PubMed
    1. Barbone F, Valent F, Pisa F, Daris F, Fajon V, Ing D, et al. Prenatal low-level methylmercury exposure and child development in an Italian costal area. Seychelles Med Dent J. 2004;7(1):149–154.
    1. Bélanger MC, Mirault ME, Dewailly E, Plante M, Berthiaume L, Noël M, et al. Seasonal mercury exposure and oxidant-antioxidant status of James Bay sport fishermen. Metabolism. 2008;57(5):630–636. - PubMed
    1. Belles-Isles M, Ayotte P, Dewailly E, Weber JP, Roy R. Cord blood lymphocyte functions in newborns from a remote maritime population exposed to organochlorines and methyl-mercury. J Toxicol Environ Health A. 2002;65(2):165–182. - PubMed

Publication types

LinkOut - more resources