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

Gaseous and soil OCPs and PCBs along the Indus River, Pakistan: spatial patterns and air–soil gradients

“…44 These areas are also characterized by mid altitude forest land and canopy interception which may play an important role in capturing the suspended particulate material from the surrounding areas and finally raising POP levels in the vegetation and soil of these areas. 1,4 Nevertheless, Bhakkar and Layyah showed net volatilization of DDTs due to historical agricultural activities. Although Abbottabad, Islamabad and Hyderabad showed ff ratios >0.5, suggesting net volatilization due to rapid urbanization and land use change (deforestation), this may be a result of emission of accumulated POP residues via soil volatilization processes in the context of micro-climatic change.…”

“…The Gulibagh Swat and Gilgit sites in the FMZ exhibited the highest concentration of DDTs (50-343 ng g −1 ), which highlighted the current illegal application of these banned pesticides for crop protection (i.e., fruits and vegetables). 1,4,17 Another reason for the high DDT concentrations in the FMZ could be LRAT from the low altitude areas to these high altitude valleys. A possible justication of POP build-up levels in the soils of these colder areas is the very high temperature and low organic matter content in the low altitude arid/semi-arid areas, which emitted most of the OCPs through volatilization and short and long term dust transportation to colder areas where they deposited into organic matter rich soils for longer times.…”

“…These trends indicated that in the colder regions (FMZ), the POP burden was dominated by transboundary movement via the LRAT process, which may act as a secondary source of POPs in these areas and re-emit through melting snow during the summer season. 1,4,17 Nevertheless, local sources also contributed towards the recent emission of these toxic chemicals and transportation into the Indus River ecosystem by wet/dry deposition processes. 7,17 In addition, lesser Himalayan areas were experiencing a signicant inuence from local land-use change in the Indus River oodplain and Indian Punjab and receiving several atmosphere mediated chemical impurities from these areas.…”

“…4 This may be due to POPs and other contaminants being ushed away due to strong air currents and these areas also experienced oods in previous years, which resulted in high uxes of POPs into the Arabian Sea. 1,4,17…”

“…due to their persistent nature and lipophilic properties. [1][2][3] Given that OCPs and PCBs are semivolatile in nature, these chemicals have the capability for long-range atmospheric transport (LRAT) to remote colder areas and may pose several ecological risks to the wildlife and human populations of these areas. 3,4 Moreover, the impacts of climate change also greatly affect the global and regional atmospheric air circulation, which ultimately inuences the trans-boundary movement, fate, and transport of POPs in different environmental compartments at local, regional and global scales.…”