Prenatal methylmercury exposure as a cardiovascular risk factor at seven years of age

Blood pressure in childhood is an important determinant of hypertension ris k later in life, and methylmercury exposure is a potential environmental ri sk factor. A birth cohort of 1,000 children from the Faroe Islands was exam ined for prenatal exposure to methylmercury, and at age 1 years, blood pres sure, heart rate, and heart rate variability were determined. After adjustm ent for body weight, diastolic and systolic blood pressure increased by 13. 9 mmHg [95% confidence limits (CL) = 7.4, 20.4] and 14.6 mmHg (95% CL = 8.3 , 20.8), respectively, when cord blood mercury concentrations increased fro m 1 to 10 mu g/liter cord blood. Above this level, which corresponds to a c urrent exposure limit, no further increase was seen. Birth weight acted as a modifier, with, the mercury effect bring stronger in children with lower birth weights. In boys, heart rate variability decreased with increasing me rcury exposures, particularly from 1 to 10 mu g/liter cord blood, at which the variability was reduced by 47%, (95% CL = 14%, 68%). These findings sug gest that prenatal exposure to methylmercury may affect the development of cardiovascular homeostasis.