NEW DEVELOPMENTS IN 2003

The Committee considered this PTWI to be sufficient to protect the developing fetus, the most sensitive subgroup of the population. The Committee also reaffirmed its position that fish are an important part of a balanced nutritious diet and that this has to be appropriately considered in public health decisions when setting limits for methylmercury concentrations in fish.

NEW DEVELOPMENTS IN 2006

JECFA, during its sixty-seventh meeting in Rome, 20-29 June 2006 made some additional considerations relating to the provisional tolerable weekly intake (PTWI) for methylmercury as follows: 

The Committee made it clear that the previous PTWI of 3.3 µg/kg bw had, in fact, been withdrawn in 2003. The Committee confirmed the existing PTWI of 1.6 µg/kg bw, set in 2003, based on the most sensitive toxicological end-point (developmental neurotoxicity) in the most susceptible species (humans). However, the Committee noted that life-stages other than the embryo and fetus may be less sensitive to the adverse effects of methyl mercury. 

In the case of adults, the Committee considered that intakes of up to about two times higher than the existing PTWI of 1.6 µg/kg bw would not pose any risk of neurotoxicity in adults, although in the case of women of childbearing age, it should be borne in mind that intake should not exceed the PTWI, in order to protect the embryo and fetus. 

Concerning infants and children aged up to about 17 years, the data do not allow firm conclusions to be drawn regarding their sensitivity compared to that of adults. While it is clear that they are not more sensitive than the embryo or fetus, they may be more sensitive than adults because significant development of the brain continues 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 for infants and children. 

The Committee has previously noted that fish makes an important contribution to nutrition, especially in certain regional and ethnic diets. The present Committee recommends that the known benefits of fish consumption need to be taken into consideration in any advice aimed at different subpopulations. Risk managers may wish to consider whether specific advice should be given concerning children and adults, after weighing the potential risks and benefits. 

The Committee concluded that the setting of guideline levels for methyl mercury 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 provide an effective method for lowering the number of individuals with exposures greater than the PTWI. 

For more detailed information, see 

• FAO/WHO, 2003: Summary and conclusions of the sixty-first meeting of the Joint FAO/WHO Expert Committee on Food Additives (JECFA), Rome, 10-19 June 2003;  JECFA/61/SC  
  and 
• FAO/WHO, 2006:  Summary and conclusions of the sixty-seventh meeting of the Joint FAO/WHO Expert Committee on Food Additives (JECFA), 20-29 June 2006; JECFA 67/SC

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