Emissions of polycyclic aromatic hydrocarbons from primitive e-waste recycling: Particle size dependence and potential health risk

Highlights: • Particulate and gaseous PAHs dominate the total emissions in thermal treatment and open burning, respectively. • Gas-particle partitioning of PAHs is governed by absorption. • Significantly high cancer risk is incurred for e-waste recycling workers. • Particles, especially fine particles enriched with heavy PAHs, are largely responsible for cancer risk. Polycyclic aromatic hydrocarbons (PAHs) with great health implications have been identified as important by-products during primitive obsolete electronics (e-waste) recycling activities. Their distribution patterns and human exposure levels are highly particle size dependent, but have not been adequately examined due to the lack of emission data. The present study was conducted to address this issue by measuring the emissions of PAHs from thermal treatment and open burning of typical e-waste pieces. The emission factors from thermal treatment and open burning of plastic casings were 3.15 × 10⁴–1.56 × 10⁵ and 4.22 × 10³–1.96 × 10⁴ ng g⁻¹, respectively, with 6.37 × 10⁴–2.17 × 10⁵ and 1.98 × 10³–2.68 × 10³ ng g⁻¹ for printed circuit boards, respectively. Low-molecular-weight PAHs predominated the total PAH emissions in both procedures. Particulate PAHs contributed the most emissions in thermal treatment, but gaseous PAHs predominated in open burning. Generally, the size distributions of particle matter and PAHs were characterized by a unimodal shape peaking at 0.56–1 or 0.32–0.56 μm. Most PAHs especially high-molecular-weight ones were found on fine particles. Absorption appeared to be the main mechanism at emission sources and re-distribution of PAHs may have occurred between particulate and gaseous phases during progressive dispersal from combustion sources. High cancer risk (7.23 × 10⁻⁴) was incurred for e-waste recycling workers via inhalation and dermal absorption, mostly attributed to the exposure of fine particles. Improved techniques are needed to reduce potential health risk for e-waste recycling workers and residents living in adjacent areas.