First results on prenatal exposure to mercury


Mercury is a ubiquitous environmental contaminant with distributionthat comes from both natural sources and human activityDiet is themain source of exposure in the general populationespecially the consumption of fish. The big blue fish, like the emperor, shark or tuna,is the one with the highest concentrations.

Mercury, particularly methylmercury, its organic formis known to beneurotoxic in humans. The vulnerability of the nervous system to these substances increases during development, especially during the prenatal stage, since the ingested methylmercury can cross the placenta and blood brain barrier.

Epidemiological studies worldwide have tried to assess the possible effects of prenatal exposure to mercury, primarily related to a diet rich in certain types of fish, onneuropsychological development in childhood. However, the results have been controversialsince some of these studies found evidence of inverse associationbetween prenatal exposure to mercury and scores on tests of neurodevelopment, butnot in others. Importantly, fish intake during pregnancy leads to a contribution ofpolyunsaturated fatty acids and trace elements essential for fetal growth and neurodevelopment.

Study in cord blood samples in 1880 newborns

In the INMA Project has studied prenatal exposure to mercury levels in analyzing cord blood samples in 1880 newborn cohort of Valencia, Sabadell, Asturias and Gipuzkoa.

These levels (geometric mean = 8.4 mg total mercury / L95{3effe4377b6f02be2524d084f7d03914ac32a2b62c0a056ca3444e58c1f10d0b} confidence interval:8.1, 8.7), were similar to those of countries and communities with a high intake ofmercury and high in comparison with other studies in some European countries and USA. These levels were mainly associated with the consumption of large predatory fishduring pregnancy, such as swordfish or emperorThis finding agrees with the results of the cohort of Menorca and Ribera d’Ebre Granada, where mercury levels in hair of children / as at 4 years was associated with the consumption of large predatory fishduring childhood.

However, prenatal exposure to mercury is not associated with adverse effects onmental and psychomotor development of children evaluated at the beginning of his second year of life. The scientific evidence on the adverse effects of mercury on neurodevelopment is inconclusive, especially with average exposures and early age-low, which justifies the need for continuous monitoring of children / as, throughout his childhood and evaluate their possible association with levels of mercury and themodifying role of diet and other variables such as family and social environment.

Sabrina Llop  graduated in Biology, Technical research, and works in the INMA cohortin Valencia