ESPE Abstracts

Background: The exposure to environmental toxicants has been estimated to contribute directly to 3% of human neurodevelopmental disabilities (NDDs). Organochlorine pesticides (OCPs), which are widespread persistent organic pollutants, have been implicated mainly because of their endocrine disruptive nature. Several studies have reported the above relations between maternal serum, the placenta barrier and the breast milk levels of OCPs and NDDs.

Aim: The aim of this cross-sectional study was to evaluate serum concentrations of dichlorodiphenyltrichloroethane (DDT) and its metabolites, hexachlorocyclohexane (HCH) and its isomers, cyclodienes and methoxychlor in serum samples from children diagnosed with High Functioning Autistic Disorder (HFA), Attention-Deficit Hyperactivity disorder (ADHD), and Moderate Learning Difficulties (MLD) compared to Typically Developing children (TD).

Method: The study sample consisted of 114 schoolchildren of normal intelligence, aged between 6 and 13 years old, distributed into four groups: HFA (n=39), ADHD (n=21), MLD (n=32) and TD (n=18). Serum concentrations of OCPs were determined by gas chromatography. Total cholesterol and triglyceride levels were evaluated by an enzymatic colorimetric method.OCPs concentrations were adjusted for serum total lipids and are presented as nanograms/gram lipid.

Main Results: Each clinical group was compared to the TD group. The levels of β-HCH, ΣHCHs (i.e. the total concentration of HCH isomers) and 2,4′DDD (i.e. a DDT breakdown product) were significantly higher in HFA children: HFA vs. TD, mean ± SD: 10.5±7.7 vs. 6.1±4.0, P=0.049; 12.0±10.3 vs. 6.6±4.0, P=0.025; 7.4±6.5 vs. 2.8±2.3, P=0.0019, respectively. Interestingly, the detection rates (i.e., at least one substance from the group detected) of 4,4′DDT, ΣDDTs and Heptachlor epoxide (group of Cyclodienes), were significantly lower in HFA children: HFA vs TD: 12.8% vs. 38.9%, P=0.037; 69.2% vs. 94.4%, P=0.044; 10.3% vs. 38.9%, P=0.026, respectively. No statistically significant differences regarding both the concentrations and the detection rates of OCPs were found between the ADHD or MLD groups and the TD group.

Conclusion: Our findings demonstrate higher serum concentrations and lower detection rates of selected OCPs in HFA children than TD children. No differences were observed between the ADHD or MLD group and TD children. These findings are in line with previous studies reporting that exposure to environmental toxicants during the fetal period, infancy and early childhood is associated with NDDs in children. Yet comprehensive evidence in children is limited, highlighting the need for in-depth research towards the understanding of possible mechanisms linking OCPs with autism spectrum disorders.