Exposure of polychlorinated naphthalenes (PCNs) to Pakistani populations via non-dietary sources from neglected e-waste hubs: A problem of high health concern

To date limited information’s are available concerning unintentional productions, screening, profiling, and health risks of polychlorinated naphthalenes (PCNs) in ambient environment and occupational environment. Literature reveals that dust is a neglected environmental matrix never measured for PCNs. To our knowledge, this is the first study to investigate the concentrations and health risks of PCNs in indoor dust, air, and blood of major e-waste recycling hubs in Pakistan. Indoor air (n = 125), dust (n = 250), and serum (n = 250) samples were collected from five major e-waste hubs and their vicinity to measure 39 PCN congeners using GC-ECNI-MS. ∑₃₉PCN concentrations in indoor air, dust, and serum (worker > resident > children) samples ranged from 7.0 to 9583 pg/m³, from 0.25 to 697 ng/g, and from 0.15 to 401 pg/g lipid weight, respectively. Predominant PCN congeners in indoor air and dust were tri- and tetra-CNs, while tetra- and penta-CNs were dominant in human serum samples. The higher PCNs contribution was recorded at the recycling units, while the lower was observed at the shops of the major e-waste hubs. Higher contribution of combustion origin CNs in air, dust and human samples showed combustion sources at the major e-waste hubs, while Halowax and Aroclor based technical mixture showed minor contribution in these samples. Mean toxic equivalent (TEQ) concentrations of PCNs were 2.79E⁺⁰⁰ pg-TEQ/m³, 1.60E⁻⁰² ng-TEQ/g, 8.11E⁻⁰¹ pg-TEQ/g, 7.14E⁻⁰¹ pg-TEQ/g, and 6.37E⁻⁰¹ pg-TEQ/g for indoor air, dust, and serum samples from workers, residents, and children, respectively. In our study, CNs- 66/67 and −73 in indoor air, dust, and human serum were the great contributors to total TEQ concentrations of PCNs. This first base line data directs government and agencies to implement rules, regulation to avoid negative health outcomes and suggests further awareness in regard of provision of proper knowledge to the target population.