Effects of pre and postnatal exposure to low levels of polybromodiphenyl ethers on neurodevelopment and thyroid hormone levels at 4 years of age.
There are at present very few studies of the effects of polybromodiphenyl ethers (PBDEs), used as flame retardants in consumer products, on neurodevelopment or thyroid hormone levels in humans. The present study aims to examine the association between pre and postnatal PBDE concentrations and neurodevelopment and thyroid hormone levels in children at age 4years and isolate the effects of PBDEs from those of PCBs, DDT, DDE and HCB. A prospective birth cohort in Menorca (Spain) enrolled 482 pregnant mothers between 1997 and 1998. At 4years, children were assessed for motor and cognitive function (McCarthy Scales of Children's Abilities), attention-deficit, hyperactivity and impulsivity (ADHD-DSM-IV) and social competence (California Preschool Social Competence Scale). PBDE concentrations were measured in cord blood (N=88) and in serum of 4years olds (N=244). Among all congeners analyzed only PBDE 47 was quantified in a reasonable number of samples (LOQ=0.002ng/ml). Exposure to PBDE 47 was analyzed as a dichotomous variable: concentrations above the LOQ (exposed) and concentrations below (referents). Scores for cognitive and motor functions were always lower in children pre and postnatally exposed to PBDE47 than in referents, but none of these associations was statistically significant (β coefficient (95%CI) of the total cognition score: -2.7 (-7.0, 1.6) for postnatal exposure, and -1.4 (-9.2, 6.5) for prenatal exposure). Postnatal exposure to PBDE 47 was statistically significantly related to an increased risk of symptoms on the attention deficit subscale of ADHD symptoms (RR (95%CI)=1.8 (1.0, 3.2)) but not to hyperactivity symptoms. A statistically significant higher risk of poor social competence symptoms was observed as a consequence of postnatal PBDE 47 exposure (RR (95%CI)=2.6 (1.2, 5.9)). Adjustment for other organochlorine compounds did not influence the results. Levels of thyroid hormones were not associated to PBDE exposure. This study highlights the importance of assessing the effects of PBDE exposure not just prenatally but also during the early years of life. In the light of current evidence a precautionary approach towards PBDE exposure of both mothers and children seems warranted.
Center for Research in Environmental Epidemiology (CREAL), Dr. Aiguader 88, 08003 Barcelona, Spain. mgascon@creal.cat
Mireia
M
Gascon
Martine
M
Vrijheid
David
D
Martínez
Joan
J
Forns
Joan O
JO
Grimalt
Maties
M
Torrent
Jordi
J
Sunyer
D000293:Adolescent; D000328:Adult; D001289:Attention Deficit Disorder with Hyperactivity / Q000453:epidemiology; D002652:Child Behavior / Q000187:drug effects; D002657:Child Development / Q000187:drug effects; D002675:Child, Preschool; D003071:Cognition / Q000187:drug effects; D004781:Environmental Exposure / Q000032:analysis / Q000706:statistics & numerical data*; D004785:Environmental Pollutants / Q000097:blood / Q000378:metabolism / Q000633:toxicity; D005260:Female; D005312:Fetal Blood / Q000378:metabolism; D005411:Flame Retardants / Q000378:metabolism / Q000633:toxicity*; D055768:Halogenated Diphenyl Ethers / Q000097:blood / Q000633:toxicity*; D006801:Humans; D008297:Male; D009043:Motor Activity / Q000187:drug effects; D009420:Nervous System / Q000187:drug effects* / Q000254:growth & development / Q000378:metabolism; D011247:Pregnancy; D011297:Prenatal Exposure Delayed Effects / Q000097:blood / Q000139:chemically induced / Q000453:epidemiology*; D013963:Thyroid Hormones / Q000097:blood*; D055815:Young Adult
D004785:Environmental Pollutants; D005411:Flame Retardants; D055768:Halogenated Diphenyl Ethers; D013963:Thyroid Hormones