Molecularly tracing of children exposure pathways to environmental organic pollutants and the Autism Spectrum Disorder Risk

Abstract

Organic pollutants (OPs) including organochlorine pesticides (OCPs), polychlorinated biphenyls (PCBs), polybrominated diphenyl ethers (PBDEs) and polycyclic aromatic hydrocarbons (PAHs) have showed neuro-damaging effects, but studies concerning the autism spectrum disorder (ASD) risk are limited. A case-control study with ASD (n = 125) and healthy control (n = 125) children was conducted on the different land use settings across Punjab, Pakistan. Serum concentrations of 26 OCPs, 29 PCB congeners, 11 PBDEs and 32 PAHs were measured. Serum PCB77 (AOR = 2.00; 95% CI: 1.43, 2.18), PCB118 (AOR = 1.49; 95% CI: 1.00, 2.00), PCB128 (AOR = 1.65; 95% CI: 1.01, 1.91), PCB153 (AOR = 1.80; 95% CI: 1.55, 1.93) were significantly higher, but PCB187 (AOR = 0.37; 95% CI: 0.24, 0.49) was significantly lower in the ASD cases when compared to the controls. Serum BDE99 (AOR = 0.48; 95% CI: 0.26, 0.89) was significantly higher in the healthy controls than in the ASD cases. Among the analyzed OCPs, p,p'-DDE (AOR = 1.50; 95% CI: 1.00, 1.85) was significantly elevated in the ASD cases with comparison in the controls. For PAHs, serum dibenzothiophene (AOR = 7.30; 95% CI: 1.49, 35.85) was significantly higher in the ASD, while perylene (AOR = 0.25; 95% CI: 0.06, 1.10) and fluorene (AOR = 0.21; 95% CI: 0.06, 0.72) were significantly higher in the controls. In addition, many of the serum pollutants were significantly associated with GSTT1, GSTM1 (null/present polymorphism) and presented the genotypic variation to respond xenobiotics in children. The children living in proximity to urban and industrial areas had a greater exposure to most of the studied pollutants when compared to the rural children, however children residing in rural areas showed higher exposure to OCPs. This comprehensive study documents an association between environmental exposure risk of several organic pollutants (OPs) from some contaminated environmental settings with ASD risk in children from Pakistan.

Keywords: Autism spectrum disorder; Estimated daily intake; Organic pollutants; Organochlorine pesticide; Pakistan; Polyaromatic hydrocarbons; Polybrominated diphenyl ethers; Polychlorinated biphenyls.