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.

Liquid crystal monomers (LCMs) in liquid crystal displays (LCDs) may be released into the environment, especially in electronic waste (e-waste) recycling industrial parks with a high pollution risk. However, little has been known about the environmental release and human exposure to LCMs until now. Herein, a total of 45 LCMs were detected in LCDs of commonly used smartphones and computers by high-resolution mass spectrometry with suspect screening analysis. Fluorinated biphenyls and their analogs were the dominant LCMs. Based on available standards of the screening results and previous studies, 55 LCMs were quantified in samples from an e-waste recycling industrial park in Central China. The LCMs were frequently detected in outdoor dust (n = 43), workshop #1 indoor dust (n = 53), and hand (n = 43) and forehead wipes (n = 43), with median concentrations of 6950 ng/g, 67,400 ng/g, 46,100 ng/m2, and 62,100 ng/m2, respectively. The median estimated daily intake values of the LCMs via dust ingestion and dermal absorption were 48.3 and 16.5 ng/kg body weight/day, respectively, indicating a high occupational exposure risk of these compounds. In addition, 16 LCMs were detected in the serum of eight elderly people (≥60 years old) with over 5 years of experience in e-waste dismantling operations, resulting in a total concentration range of 3.9–26.3 ng/mL.

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A landfill is an important sink of plastic waste and potential sources of microplastics (MPs) when mineralized refuse is reused. However, limitations are still present in quantifying MPs in mineralized refuse and assessing their degradation degree. In this study, laser direct infrared spectroscopy and liquid chromatography-tandem mass spectrometry (LC-MS/MS) were used to identify MPs of mineralized refuse from a landfill. Although 25− 113 items/g MPs were detected in particles subjected to flotation, 37.9−674 μg/g polyethylene terephthalate (PET) and 0.0716− 1.01 μg/g polycarbonate (PC) were detected in the residual solids by LC-MS/MS, indicating a great amount of plastic polymers still presented in the residue. This suggests that the commonly used flotation-counting method will lead to significant underestimation of MP pollution in mineralized refuse, which might be due to the aging and aggregation process caused by the long-term landfill process. The ratio of "bisphenol A/PC" and "plasticizer/MPs" was found to be positively correlated and negatively correlated with the landfill age, respectively. Therefore, in addition to the spectral index such as the carbonyl index, new indexes based on the concentrations of polymers, free monomers, and plasticizers were proposed to characterize the degradation degree of MPs in a landfill.