METHYLMERCURY

General Information


CAS number: 593-74-8
Functional Class:
  • Food Contaminant
    • METALS

Evaluations


Evaluation year: 2007
Comments: The Committee confirmed that the previous PTWI of 3.3 µg/kg bw had been withdrawn in 2003. The Committee confirmed the existing PTWI of 1.6 µg/kg bw, based on the most sensitive toxicological end-point (developmental neurotoxicity) in the most susceptible species (humans). For adults, the Committee considered that intakes of up to two times higher than the existing PTWI would not pose any risk of neurotoxicity, although in the case of women of childbearing age, intake should not exceed the PTWI in order to protect the embryo and fetus. Concerning infants and children up to 17 years, no firm conclusions may be drawn regarding their sensitivity compared to that of adults. While they are clearly not more sensitive than the embryo or fetus, they may be more sensitive than adults due to continuing neurodevelopment in infancy and childhood. Therefore, the Committee could not identify a level of intake higher than the existing PTWI that would not pose a risk of developmental neurotoxicity. The Committee has previously noted that fish makes an important contribution to nutrition, especially in certain regional and ethnic diets and recommends that the known benefits of fish consumption be taken into consideration in any advice aimed at different subpopulations. The Committee concluded that the setting of guideline levels for methylmercury in fish may not be an effective way of reducing exposure for the general population. The Committee noted that advice targeted at population subgroups that may be at risk from methyl mercury exposure may be effective in lowering the number of individuals with exposures greater than the PTWI.
Tolerable Intake: PTWI 1.6 µg/kg bw
Meeting: 33
Report: TRS 940-JECFA 67/57
Tox Monograph: 67th_2007_methyl mercury.pdf
Previous Years: 2003, TRS 922-JECFA 61/132, FAS 52-JECFA 61/565. PTWI 0.0016 mg/kg bw.The Committee reaffirmed its position that fish is an important part of a balanced nutritious diet and that this has to be appropriately considered in public health decisions when setti
Estimated exposure

Best estimate: 0.1-2 µg/kg bw/week

Toxicological study
Pivotal Study: Epidemiology studies conducted in children from the Faroe Islands & the Seychelles (Budtz-Jorgensen et al. (1999a, 2000, 2001); United States National Research Council (2000); Rice et al. (2003), Agency for Toxic Substances and Disease Registry (1999)): Children 5.5-7 years old were assessed for neurodevelopmental endpoints, and maternal hair Hg levels were measured. An average BMDL/NOEL of 14mg/kg (14 µg/g) was derived for concentrations of mercury in maternal hair in the studies of neurodevelopmental effects, which was calculated to arise from a daily Hg intake of 1.5 µg/kg bw. The PTWI was derived by dividing this intake by a total uncertainty factor of 6.4 to give a value of 1.6 µg/kgbw.
Animal specie: Human
Effect: Neurotoxicity
NOAEL: 1.5 µg/kg
PTWI: 1.6 µg/kg bw
Point of departure: BMDL: 1.5 µg/kg