Organophosphite Antioxidants in Mulch Films Are Important Sources of Organophosphate Pollutants in Farmlands

Abstract

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.

E-Waste Recycling Emits Large Quantities of Emerging Aromatic Amines and Organophosphites: A Poorly Recognized Source for Another Two Classes of Synthetic Antioxidants

“…All the remaining OPAs, except TiDePi, PEPQ, and AO 618, could be detected but showed low DFs (< 50%). Consistent with previous studies on selected OPAs, ,− the compounds TCEPi, TPHPi, TEHPi, TiDePi, TNPPi, and AO 626 were difficult to find in other environmental matrices or were positively detected but with low levels and DFs. According to the US EPA CDR database, some OPAs, such as TPHPi and TNPPi, are also HPV chemicals similar to AO 168.…”

“…AO 168 was extensively detected in all e-waste dust samples and identified as the most abundant OPA, with the median and highest levels reaching 918 and 3.30 × 10 4 ng/g, respectively, which is 2 orders of magnitude greater than its previously reported levels in indoor dust . AO 168 is an HPV chemical recorded in the US EPA CDR database, which has been reported to be detected at very high concentrations in commercial mulch film and face masks . Our finding of highly abundant AO 168 in e-waste dust implies that it is extensively used in substantial amounts across diverse e-products, such as wires and cables.…”

“…Our finding of highly abundant AO 168 in e-waste dust implies that it is extensively used in substantial amounts across diverse e-products, such as wires and cables. Interestingly, AO 168 was rarely or not detected in outdoor matrices, such as air fine particles and film-mulching soil. , Considering the similarity in molecular structures of OPAs and OPEs, evidenced partly by previous studies, OPAs may readily undergo environmental oxidative transformation to generate OPEs, representing an important indirect source of environmental OPEs that had been previously overlooked. ,− This raises another emerging issue worthy of further concern.…”

Massive Emissions of a Broad Range of Emerging Hindered Phenol Antioxidants and Sulfur Antioxidants from E-Waste Recycling in Urban Mining: New Insights into an Environmental Source

“…Even though most of these antioxidants have been used for >10 years, the environmental pollution by many of them has not been assessed until recently. In addition to the screening of two new categories of antioxidants in this study, many others, such as organophosphite , and amine antioxidants, − may have been commonly used in e-products as well and end in e-waste. As e-products are highly related to all aspects of our daily lives, the increased use of these “novel” antioxidants in different areas of life will certainly result in their massive emissions into the environment and the chance of exposure of humans and organisms to them.…”

Single-Use Face Masks as a Potential Source of Synthetic Antioxidants to the Environment

“…Previous studies have identified high concentrations of AOs in plastic-containing products. , A recent study using nontargeted analysis identified AO168 and tris­(2,4-di- tert -butylphenyl) phosphate (AO168O) in face masks . Although previous studies have identified some AOs in both human matrices (urine, , serum, , milk, and fingernails) and environmental ones (indoor dust, − air particulates, , sludge, , soil, sediment, and water), there is very little information about whether single-use face masks may act as a source of AOs. In this study, we selected as target chemicals 15 SPAs, five OPAs, and five corresponding OPA oxidation products that have previously been detected in commercial products and environmental matrices.…”