Organophosphite antioxidants (OPAs) are important auxiliary antioxidants used in plastic polymers and can be oxidized to organophosphate esters (OPEs) during production and processing. In this work, the occurrence of OPAs and OPEs in farmlands with or without mulch film applications was investigated. Six OPAs and five OPEs were detected, with the median concentrations of 2.66 ng/g (∑ 6 OPAs) and 100 ng/g (∑ 5 OPEs) in the film-mulching soil and 1.16 ng/g (∑ 6 OPAs) and 47.9 ng/g (∑ 5 OPEs) in the nonfilm-mulching soil, respectively. The oxidative derivative of AO168 (tris (2,4-di-tert-butylphenyl) phosphite), a typical OPA, AO168O (tris (2,4-di-tert-butylphenyl) phosphate) was frequently detected in farmlands at the concentrations of 0−731 ng/g, which is much higher than that of the commercial OPEs (0−12.1 ng/g). This suggests that the oxidation derivatives of OPAs (OPAsO) might be important OPE contaminants in soils. Mulch films could be their important source. According to the simulation migration experiment, the emission risk ranges of AO168 and AO168O from mulch films to soils in China were estimated to be 3.96−87.6 and 10.5−95.3 tons/year, respectively, which were much higher than those of OPEs from sewage sludge applications. Simulation experiments also demonstrated that oxidation was the major pathway for OPAs in soils. OPAs with small substituent groups could be potential sources for organophosphate diesters. For the first time, the serious pollution of OPAs and OPAsO in soils has been reported, and mulch films have been identified as their potential source.

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The quantitative detection methods for many microplastic (MP) polymers in the environment are inadequate. For example, effective detection methods for nylon (polyamide, PA), a widely used plastic, in different environmental samples are still lacking. In the present study, a method based on acid depolymerization−liquid chromatography−tandem mass spectrometry (LC−MS/MS) and without the separation of MPs from samples was developed to quantify nylon MPs. After removing the background monomer compounds, PA6 and PA66 were efficiently depolymerized to 6-aminocaproic acid and adipic acid, respectively, and detected by LC−MS/MS. Accordingly, the quantity of nylon MPs was accurately calculated. By using the proposed method, the recovery of spiked PA6 and PA66 MPs in the environmental samples ranged from 90.8 to 98.8%. The limits of quantification for PA6 and PA66 MPs were 0.680 and 4.62 mg/ kg, respectively. PA MPs were widely detected in indoor dust, sludge, marine sediment, freshwater sediment, fishery sediment, and fish guts and gills with concentrations of 0.725−321 mg/kg. Extremely high concentrations of PA66 MPs were detected in indoor dust and fish guts and gills, indicating the unequivocal risk of human exposure through dust ingestion and dietary exposure.

Bisphenol A (BPA) is an important endocrine disrupting chemical. Although high levels of BPA in some new clothes have been reported, the occurrence of bisphenol chemicals including BPA in daily clothes is still unknown, and the human exposure to BPA in clothes has not been well assessed. In this study, used/washed clothes were collected from residents’ wardrobes and the concentrations of BPA and its analogues were detected. BPA was present in all the used clothes at concentrations ranging from <3.30 to 471 ng/g (median: 34.2 ng/g; mean ± SD: 57.5 ± 93.6 ng/g), while bisphenol S was also detected in 29% of the samples. Although higher average concentration (88.4 ± 289 ng/g) and maximum concentration (1823 ng/g) of BPA were found in the new clothes, the median concentration of BPA in the used clothes (34.2 ng/g) was even higher than that in the new clothes (17.7 ng/g). Cross contamination of BPA during laundering was identified by a simulated laundry experiment, which explained the homogenizing tendency of bisphenol contaminants in the used clothes. An estimated dermal exposure dose of 52.1 ng/kg BW/d was obtained for BPA exposure in children from the highly polluted sweaty clothes (with BPA concentration of 199 ng/g). This indicates a relatively high exposure risk in humans. Compared to other exposure routes, the contribution of dermal exposure dose of BPA from the daily clothes should not be neglected.

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