Workplace Presence and Exposure of p‑Phenylenediamines and Their Quinones in Rubber Production

p-Phenylenediamines (PPDs), widely
utilized as antioxidants
in
rubber products, have emerged as contaminants of environmental concern,
yet their fate and associated health risks in rubber manufacturing
environments remain poorly characterized. This study quantified the
occurrence and estimated worker exposure based on settled dust concentrations
of PPDs and their quinone derivatives (PPD-Qs) in two representative
rubber manufacturing sectors, i.e., tire and seal factories, and the
surrounding areas. Results showed that median concentrations of ∑PPDs
(114 μg/g) and ∑PPD-Qs (354 μg/g) in indoor workshops
far exceeded the levels in industrial park road dust (∑PPDs:
1.84 μg/g; ∑PPD-Qs: 0.410 μg/g) and surrounding
road dust (∑PPDs: 219 ng/g; ∑PPD-Qs: 217 ng/g) in tire
rubber factories. In addition, PPD and PPD-Q concentrations exhibited
interfactory disparities (tire factories exceeding seal factories
by 397-fold and 227-fold, respectively) and intrafactory variations
(peaking in high-temperature/abrasion workshops), highlighting the
necessity for targeted ventilation and protection. Distribution patterns
differed by facility type, with concentrations halving within 0.3
km of plant boundaries. This study identifies rubber manufacturing,
particularly large rubber tire plants, as a major source of PPDs and
PPD-Qs, emphasizes the need for targeted worker protection and chemical
management in high-emission zones such as mixing and vulcanizing workshops,
and provides production-specific contamination profiles to guide effective
regulatory and mitigation strategies.