Environmental exposure to polychlorinated biphenyls and quality of the home environment: effects on psychodevelopment in early childhood

Background There is uncertainty whether environmental levels of exposure to polychlorinated biphenyls (PCBs) adversely affect mental and motor develop ment in early childhood. We aimed to establish whether such an effect is of only prenatal or additional postnatal origin, and if a favourable home env ironment can counteract this effect. Methods Between 1993 and 1995 we recruited 171 healthy mother-infant pairs and prospectively measured psychodevelopment in newborn infants aged 7, 18, 30, and 42 months. We estimated prenatal and perinatal PCB exposure of new born babies in cord blood and maternal milk. At 42 months we measured postn atal PCB concentrations in serum. At 18 months the quality of the home envi ronment was assessed using the Home Observation for Measurement of the Envi ronment scale. Mental and psychomotor development of the children were asse ssed using the Bayley Scales of Infant Development until 30 months and the Kaufman Assessment Battery for Children at 42 months. Findings Negative associations between milk PCB and mental/motor developmen t were reported at all ages, becoming significant from 30 months onwards. O ver 30 months, for a PCB increase from 173 (5th percentile) to 679 ng/g lip ids in milk (95th percentile) there was a decrease of 8.3 points (95% CI -1 6.5 to 0.0) in the Bayley Scales of Infant Development mental scores, and a 9.1 point decrease (95% CI -17.2 to -1.02) in the Bayley Scales of Infant Development motor scores. There was also a negative effect of postnatal PCB exposure via breastfeeding at 42 months. Home environment had a positive e ffect from 30 months onwards (Bayley Scales of Infant Development mental sc ore increase of 9.4 points [95% CI 2.2-.16.7]). Interpretation Prenatal PCB exposure at current European background levels inhibits, and a favourable home environment supports, mental and motor deve lopment until 42 months of age. PCB exposure also has an effect postnatally .