Health Risk Characterization for Resident Inhalation Exposure to Particle-Bound Halogenated Flame Retardants in a Typical E-Waste Recycling Zone

Abstract

Inhalation of pollutants is an important exposure route for causing human health hazards, and inhalation exposure assessment must take into account particle size distribution because particle-bound pollutants are size-dependent. Such information is scarce, particularly for residents dwelling within e-waste recycling zones where abundant atmospheric halogenated flame retardants (HFRs) commonly used in electronic/electrical devices have been widely reported. Atmospheric size-fractioned particle samples were collected using a 10-stage Micro-Orifice Uniform Deposit Impactor from an e-waste recycling zone in South China. The deposition efficiencies and fluxes of sizefractioned HFRs including polybrominated diphenyl ethers (PBDEs), alternative brominated flame retardants, and Dechlorane Plus in the human respiratory tract were estimated using the International Commission on Radiological Protection deposition model. The majority of HFRs was found to deposit in the head airways, with coarse particles (aerodynamic diameter (Dp) > 1.8 μm) contributing the most (69−91%). Conversely, fine particles (Dp < 1.8 μm) were dominant in the alveolar region (62−80%). The inhalation intake of PBDEs within the e-waste recycling zone was 44 ng/d (95% confidence interval (CI): 30−65 ng/d), close to those through food consumption in non-e-waste recycling regions. The estimated total hazard quotient of particle-bound HFRs was 5.6 × 10 −4 (95%

Potential health risk for residents around a typical e-waste recycling zone via inhalation of size-fractionated particle-bound heavy metals

“…Besides Mn and As, 60% and 30% of the HQ values of Ni and Cd for children were also higher than 1. By comparison, the HQ values of total metals for adults were much greater than those of brominated and organophosphate flame retardants (5.6 × 10 −4 and 3.0 × 10 −4 ) [12,13], i.e., heavy metals pose stronger chronic non-cancer health hazards than these organic contaminants. In addition, the total ILCR of Cr, Co, Ni, As, and Cd for adults (1.3 × 10 −3 ; 95% CI: 4.1 × 10 −4 -3.0 × 10 −3 ) and children (3.9 × 10 −3 ; 95% CI: 1.3 × 10 −3 -8.6 × 10 −3 ) were substantially higher than the acceptable cancer risk threshold of 10 −6 set forth by the United States Environmental Protection Agency [22] (Fig.…”

“…By comparison, inhalation exposure is perhaps the hardest to alleviate. Our previous study demonstrated that the inhalation intake rate of particle-bound polybrominated diphenyl ethers in the e-waste recycling zone was similar to those through food consumption in the urban regions [12]. Although the health risk for residents was low from inhalation exposure to particle-bound brominated and organophosphate flame retardants [12,13], the amounts of heavy metals released from e-waste recycling activities were 1-2 orders of magnitude greater than those of organic pollutants [1], thereby human health effects induced from heavy metals must be further evaluated.…”

“…The fractions of inhaled particles deposited in three main parts of the human respiratory tract, i.e., head airways (HA, including nose, mouth, pharynx, and larynx), tracheobronchial region (TB), and alveolar region (AR) [12,17] were calculated. In particular, the deposition efficiency of a size-specific particle in the head airway (DF HA,i ), tracheobronchial region (DF TB,i ), and alveolar region (DF AR,i ) can be estimated by…”

“…Hence these elements were selected to estimate the ILCR. The formulas for calculating CDI, HQ, and ILCR are as follows [12,19,21,22]:…”

“…Most research efforts appear to have focused on health risk assessment based on total suspended particles, which may overestimate health risk from inhalation exposure [12,14,15]. Therefore, the size dependence of inhalation exposure should be considered.…”