N,N'-Substituted p-phenylenediamines (PPDs) are widely used as antioxidants in the rubber industry and are released into the environment in large quantities during the production and use of rubber products. We quantified PPDs and PPD quinone derivatives (PPD-Qs) in rubber consumer products, including car tires, rubber belts, rubber gloves, rubber cables, and rubber hoses, to obtain information on the degree of weathering over time during their use. Additionally, we investigated the occurrences and sources of PPDs and PPD-Qs in dust samples collected from four typical urban environments (roads, parking lots, automotive repair shops, and residences). The detected compounds included the highly toxic N-(1,3-dimethylbutyl)-N'-phenyl-1,4-phenylenediamine quinone, which can cause acute mortality of coho salmon (Oncorhynchus kisutch). Concentrations of PPDs in the automotive repair shops reached 56.0 μg/g, and were much higher than in the other environments, while the residential samples had the lowest contaminant concentrations. In road and residential samples, N,N'-di-2-naphthyl-p-phenylenediamine accounted for 17 %-30 % of the PPDs, and may have originated from different sources. We preliminarily identified 32 transformation products, and 11 of these were N,N'-di-2-naphthyl-p-phenylenediamine transformation products. The average daily intakes of PPDs and PPD-Qs were calculated to assess the health risks of dust exposure in each environment. Workers had high total intakes of PPD [60.3 ng/(kg day)] and PPD-Qs [20.1 ng/(kg day)], and were at some risk of occupational exposure. These results improve our understanding of the environmental occurrences, sources, transformation, and health risks of PPDs and PPD-Qs.

The conservation and sustainability of the Yongding River Watershed attracted great attention as Beijing and Zhangjiakou jointly hosted the Winter Olympics in 2022. The government has implemented many management measures and restoration programs in the past decade. However, information and opinions from the public perspective were rarely considered. This paper investigates 626 residents neighboring the Yongding River Watershed through a face-to-face questionnaire survey to reveal public perceptions, attitudes, concerns, and behaviors toward sustainable watershed protection and proposes multiple regression models to explore factors affecting their concerns and behaviors. The results show that the majority of respondents (52–58%) have limited knowledge about the watershed environment, and their views are influenced by living places. More than half of the respondents (52%) believe that upstream should take responsibility for watershed protection, but 72% are not aware that upstream suffers economic restrictions. Public behaviors toward watershed protection are diverse depending on knowledge, attitudes, and concerns about the watershed environment as well as on sociodemographic background. Our results highlight that a better understanding of watershed protection can be used to foster public participation and increase support for watershed management initiatives.

The Chinese mitten crab (Eriocheir sinensis) holds significant importance as a popular aquaculture food source; however, there are concerns about its potential contamination with polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs), polychlorinated biphenyls (PCBs) from both food and aquatic environment. To assess the associated health risks and identify potential sources of contamination in crabs, a comprehensive investigation was conducted, including a total of 70 samples from the crab food web. The results demonstrated that crabs predominantly exhibited elevated concentrations of PCBs and dl-PCBs, with mean concentrations of 12 207 ± 11 962 pg g^-1 and 554 ± 203 pg g^-1, respectively, while PCDD/Fs concentrations were comparatively lower at 20 ± 17 pg g^-1. The accumulation of PCBs in crabs significantly surpassed that of PCDD/Fs. The material balance of PCDD/Fs and PCBs in the crab food web was estimated, indicating that sediments and feeds likely constitute the two primary sources of PCDD/Fs and PCBs in crabs. The monthly intake of PCDD/Fs and PCBs through crab consumption accounted for 30% of the dietary intake, which was well below the provisional tolerable monthly intake (PTMI) limit. The weekly intake of PCDD/Fs and PCBs for adults consuming one crab (100 g) does not pose health risks and the recommended weekly intake of white crabmeat and brown crabmeat is 443 g and 21 g, respectively.