title: Prenatal methylmercury exposure and language delay at three years of age in the Norwegian Mother and Child Cohort Study.
abstract: Prenatal methylmercury (MeHg) exposure and its possible neurodevelopmental effects in susceptible children are of concern. Studies of MeHg exposure and negative health outcomes have shown conflicting results and it has been suggested that co-exposure to other contaminants and/or nutrients in fish may confound the effect of MeHg. Our objective was to examine the association between prenatal exposure to MeHg and language and communication development at three years, adjusting for intake of fish, n-3 long chain polyunsaturated fatty acids (n-3 LCPUFAs) and co-exposure to dioxins and dioxin like polychlorinated biphenyls (dl-PCBs). We used data from the Norwegian Mother and Child Cohort Study (MoBa) collected between 2002 and 2008. The study sample consisted of 46,750 mother-child pairs. MeHg exposure was calculated from reported fish intake during pregnancy by a FFQ in mid-pregnancy. Children's language and communication skills were measured by maternal report on the Dale and Bishop grammar rating and the Ages and Stages communication scale (ASQ). We estimated odds ratios (OR) and 95% confidence intervals (CI) using logistic regressions. Median MeHg exposure was 1.3μg/day, corresponding to 0.14μg/kgbw/week. An exposure level above the 90th percentile (>2.6μg/day, >0.29μg/kgbw/week) was defined as the high MeHg exposure. Results indicated an association between high MeHg exposure and unintelligible speech with an adjusted OR 2.22 (1.31, 3.72). High MeHg exposure was also associated with weaker communication skills adjusted OR 1.33 (1.03, 1.70). Additional adjustment for fish intake strengthened the associations, while adjusting for PCBs and n-3 LCPUFA from diet or from supplements had minor impact. In conclusion, significant associations were found between prenatal MeHg exposure above the 90th percentile and delayed language and communication skills in a generally low exposed population.
authors.affiliation: Norwegian Institute of Public Health, P.O. Box 4404 Nydalen, NO-0403 Oslo, Norway. Electronic address: kristine.vejrup@fhi.no.
authors.forename: Kristine
authors.initials: K
authors.lastname: Vejrup
authors.affiliation: Norwegian Institute of Public Health, P.O. Box 4404 Nydalen, NO-0403 Oslo, Norway.
authors.forename: Synnve
authors.initials: S
authors.lastname: Schjølberg
authors.affiliation: Norwegian Institute of Public Health, P.O. Box 4404 Nydalen, NO-0403 Oslo, Norway.
authors.forename: Helle Katrine
authors.initials: HK
authors.lastname: Knutsen
authors.affiliation: Bjørknes College, Lovisenberggata 13, 0456 Oslo, Norway.
authors.forename: Helen Engelstad
authors.initials: HE
authors.lastname: Kvalem
authors.affiliation: Norwegian Institute of Public Health, P.O. Box 4404 Nydalen, NO-0403 Oslo, Norway.
authors.forename: Anne Lise
authors.initials: AL
authors.lastname: Brantsæter
authors.affiliation: Norwegian Institute of Public Health, P.O. Box 4404 Nydalen, NO-0403 Oslo, Norway.
authors.forename: Helle Margrete
authors.initials: HM
authors.lastname: Meltzer
authors.affiliation: Norwegian Institute of Public Health, P.O. Box 4404 Nydalen, NO-0403 Oslo, Norway.
authors.forename: Jan
authors.initials: J
authors.lastname: Alexander
authors.affiliation: Norwegian Institute of Public Health, P.O. Box 4404 Nydalen, NO-0403 Oslo, Norway.
authors.forename: Per
authors.initials: P
authors.lastname: Magnus
authors.affiliation: Norwegian Institute of Public Health, P.O. Box 4404 Nydalen, NO-0403 Oslo, Norway.
authors.forename: Margaretha
authors.initials: M
authors.lastname: Haugen
mesh_terms: D000818:Animals; D002648:Child; D002675:Child, Preschool; D015331:Cohort Studies; D015986:Confounding Factors, Epidemiologic; D004032:Diet; D004147:Dioxins / Q000032:analysis / Q000633:toxicity; D015525:Fatty Acids, Omega-3 / Q000032:analysis; D005260:Female; D005399:Fishes; D005506:Food Contamination / Q000032:analysis; D005865:Gestational Age; D006801:Humans; D007805:Language Development Disorders / Q000139:chemically induced / Q000453:epidemiology*; D008297:Male; D018811:Maternal Exposure / Q000009:adverse effects*; D008767:Methylmercury Compounds / Q000032:analysis* / Q000633:toxicity; D009664:Norway / Q000453:epidemiology; D011078:Polychlorinated Biphenyls / Q000032:analysis / Q000633:toxicity; D011247:Pregnancy; D011297:Prenatal Exposure Delayed Effects / Q000139:chemically induced*; D011446:Prospective Studies; D014874:Water Pollutants, Chemical / Q000032:analysis* / Q000633:toxicity
chemical_list: D004147:Dioxins; D015525:Fatty Acids, Omega-3; D008767:Methylmercury Compounds; D014874:Water Pollutants, Chemical; D011078:Polychlorinated Biphenyls
keywords: Diet; Fish intake; Language development; Methylmercury; Neurodevelopment; Norwegian Mother and Child Cohort Study; Prenatal exposure