Motor development following in utero exposure to organochlorines: a follow-up study of children aged 5-9 years in Greenland, Ukraine and Poland

Background: Prior studies on the association between prenatal exposure to polychlorinated biphenyls (PCBs) and dichlorodiphenyldichloroethylene (DDE) and child motor development have found contradicting results. Using data collected in the INUENDO cohort in Kharkiv (Ukraine), Warsaw (Poland) and Greenland (N = 1,103) between the years 2002 and 2012, we examined relations of prenatal exposure to 1,1-dichloro-2,2-bis(p-chlorophenyl) ethylene (p, p'-DDE) and 2,2', 4,4', 5,5'-hexachlorobiphenyl (CB-153) on motor development and developmental milestones; crawling, standing-up and walking. Methods: CB-153 and p, p'-DDE were measured in maternal blood in second or third trimester of pregnancy. Motor development was measured in terms of the parentally assessed screening tool Developmental Coordination Disorder Questionnaire 2007 and developmental milestones were assessed via retrospective parental reports of child age at the first time of crawling, standing-up and walking. Results: We saw no associations between tertiles of CB-153 and p, p'-DDE or log-transformed exposures and retrospective reports of the developmental milestones crawling, standing-up and walking in infancy or the motor skills measured as developmental coordination disorder at young school age. Conclusions: In utero exposure to CB-153 and p, p'-DDE was not associated with parentally retrospectively assessed developmental milestones in infancy or parentally assessed motor skills at young school age. The use of a more sensitive outcome measure may be warranted if subtle effects should be identified.