Exposure and human health risk assessment of chlorinated paraffins in indoor and outdoor dust from a metropolitan city, Lahore, Pakistan

Chlorinated paraffins (CPs) are widely used in commercial products due to their stability and durability and are subsequently released in the environment posing serious health risks in human population. In this study, dust samples from indoor and outdoor settings of residential, commercial and industrial zones as well as from vehicles were collected from a metropolitan city, Lahore, Pakistan. A total of 83 dust samples were analyzed for short (SCCPs) and medium (MCCPs) chained CPs through quadrupole time of flight mass spectrometer in atmospheric pressure chemical ionization (APCI QToF-MS) mode. The median concentrations of ƩCPs (C10-17) in outdoor dust were higher than indoor dust in industries (0.97 vs 0.48 μg/g), and residential areas (0.70 vs 0.13 μg/g) while lower in commercial areas (0.28 vs 0.44 μg/g) reflecting their higher prevalence in industrial and residential zones. The vehicular dust had median ƩCPs of 0.16 μg/g which was similar to residential indoor dust. Overall, ƩSCCPs were dominant among all zones with C10,12 and Cl7-8 as abundant carbon and chlorine congeners in both indoor and outdoor dusts. No significant correlations were observed between indoor and outdoor dust for ƩSCCPs and ƩMCCPs indicating their varying exposure. Health hazard index and margin of exposure revealed that toddlers were at higher risk compared to adults as a results of CPs exposure from both indoor and outdoor environments. This is the first ever assessment of CPs in Pakistan reflecting higher prevalence of SCCPs than MCCPs in dust of local environment posing some serious health consequences hence needed intensive investigation and effective management.