Neurodevelopmental retardation, as assessed clinically and with magnetoencephalography and electroencephalography, associated with perinatal dioxin exposure

•Long term follow-up into adolescence of a mother-child cohort with known prenatal and lactational dioxin exposure.•41 children were tested clinically and with magnetoencephalography (MEG) and electroencephalography (EEG).•Higher prenatal dioxin exposure was associated with a 10 % longer reaction time, indicating defective myelinisation.•Higher prenatal dioxin exposure was associated with decreased cognitive ability, using odd ball, in the N200 and P300.•Clinical psychological intelligence tests and clinical neuromotor tests showed no relation with perinatal dioxin exposure. Behavioral problems at the age of 7-12 years were related to pre and postnatal dioxin exposure.•In adolescence behavioral problems were associated with current dioxin levels and levels of dioxin-like PCBs.

In 1980s Western Europe, human perinatal exposure to background levels of dioxins was rather high. We therefore evaluated the neurodevelopment of our cohort during the prepubertal period and in adolescence.At prepubertal age (7–12 years) 41 children were tested. Both neuromotor functioning and psychological testing were performed (Dutch version of the Wechsler Intelligence Scale for Children (WISC-R) and the Dutch version of the Child Behavior Checklist for ages 4–18 years (CBCL 4–18) and the Teacher Report Form (TRF)). Neurophysiological tests were performed using magnetoencephalography and electroencephalography.In adolescence (14–18 years) the behavior of 33 children was studied again (CBCL and TRF). And the levels of dioxins and dioxin-like PCBs (dl-PCBs) were measured in serum.ResultsAt prepubertal age no association was found between perinatal dioxin exposure and verbal, performal and total IQ or with the Touwen's test for neuromotor development. There were behavioral problems associated with both prenatal and postnatal dioxin exposure. In adolescence there were problems associated with the current dioxin levels and dioxin-like-PCBs.Neurophysiological tests revealed clear negative dysfunction. An increase in latency time after a motion stimulus (N2b) of 13 ms (= a delay of 10%) is associated with the higher prenatal dioxin exposure. A similar delay was measured in testing cognitive ability by analyzing the odd ball measurements, N200 and P300, together with an amplitude decrease of 12 %. The delay is indicative of a defective myelinisation and the decrease in amplitude of a loss of neurons.ConclusionWe found effects on behavior in association with the perinatal dioxin exposure and in adolescence in association with the current dioxin levels.Neurophysiological testing is instrumental in the detection of effects of perinatal background levels of chemicals on brain development in normal, healthy children. The clinical, neurological and psychological tests commonly used are not sensitive enough to detect important effects.