Omega-3 Fatty Acid and Methylmercury Effects on Intelligence Quotient (IQ) in Children Due to Prenatal Fish Exposure

ISEE-833

Background:

Fish has been recognized as a food item with various beneficial qualities but hazardous as well. Finns, among others, have been concerned about the seafood safety. The coast of Finland, the Baltic Sea, is highly polluted by organic pollutants. Methylmercury (MeHg) is also a concern when dealing with the food safety of fish. There are number of studies showing an adverse effect of MeHg on the brains and intelligence quotient (IQ). However, the beneficial effects of omega-3 fatty acids on IQ are also recognized. This makes the question of the total IQ effects due to fish consumption interesting. An important aspect is the fact that these two effects share a common metric and no conversion between different metrics is needed. Fortunately, the general population usually does not face a significant health risk from MeHg exposure. However, prenatal life is much more sensitive to the toxic effects of MeHg than adult life. Docosahexaenoic acids (DHA), a subgroup of omega-3 fatty acids, affect the brains as well by promoting brain development, particularly in children. IQ is a composite index that averages a child's performance across many functional domains, providing an overall picture of cognitive health. Child's IQ also predicts future outcomes in life such as occupational and academic success. We conducted a quantitative benefit-risk assessment of DHA and MeHg on the total IQ effects of prenatal fish consumption to children using Monte-Carlo simulation.

Methods:

We constructed different fish consumption scenarios for pregnant women and studied their effect on child's IQ. The data for the fish consumption scenarios were attained from the National Public Health Institute and the National Game and Fishery Research Institute, and concentrations of DHA in fish by using the nutritional database Fineli. To estimate the effects of MeHg, we used single-compartment model suggested by the World Health Organisation. Exposure-response function for MeHg effect based on studies conducted by Cohen et al (2005), and Axelrad et al (2007). Exposure-response function for DHA used values suggested by Cohen et al (2005).

Results and Discussion:

The small health benefits of DHA appeared to neutralize the small health risk of MeHg. The total result was very slightly on the beneficial side, depending on consumption scenarios. However, the differences between the consumption scenarios were small, and the net results were very close to zero in each scenario. We must also bear in mind that the results are not universally applicable to all parts of the World. Great geographical variation in concentrations of fish and fish intake exist. However, this study found that low level exposure to mercury in fish with the Finnish (North European) fish consumption pattern at least does not pose a large risk to the child. Conversely, the balance might be slightly on a beneficial side.