Indirect Emissions from Organophosphite Antioxidants Result in Significant Organophosphate Ester Contamination in China

Abstract

Organophosphite antioxidants (OPAs) have been seriously neglected as potential sources of organophosphate esters (OPEs) in environments. This study utilizes a modeling approach to quantify for the first time national emissions and multimedia distributions of triphenyl phosphate (TPHP)�a well-known flame retardant�and three novel OPEs: tris(2,4-ditert-butylphenyl) phosphate (AO168�O), bis(2,4-ditert-butylphenyl) pentaerythritol diphosphate (AO626�O 2 ), and trisnonylphenol phosphate (TNPP). Emphasis is on the quantitative assessment of OPA source in China. TPHP has 1.1−9.7 times higher emission (300 Mg/year in 2019 with half from OPA sources) than AO168�O (278 Mg/year), AO626�O 2 (53 Mg/year), and TNPP (32 Mg/ year), but AO168�O is predominant in environments (63−79%) except freshwaters. About 72−99% of the studied OPEs are emitted via air, with 88−99% ultimately distributed into soils as the major sink. OPA-source emissions contribute 9.5−57% and 4.7− 56% of TPHP masses and concentrations (except in sediments) in different media, respectively. Both AO168�O and AO626�O 2 exhibit high overall persistence ranging between 2 and 11 years. Source emissions and environmental concentrations are elevated in economically developed areas, while persistence is higher in northern areas, where precipitation and temperature are lower. This study shows the significance of the sources of OPA to OPE contamination, which supports chemical management of these substances.

Discovering Novel Organophosphorus Compounds in Wastewater Treatment Plant Effluents through Suspect Screening and Nontarget Analysis

“…No suspect OPAs corresponding to the identified tri-OPEs were detected in the wastewater samples, although they are abundant in product materials and areas near emission sources, , indoor dust, − and airborne particles. , The absence of OPAs in WWTP effluents may be ascribed to their poor stability under environmental conditions ,,, or biotransformation during wastewater treatment. Note that corresponding OPEs are recognized as the predominant oxidation products of OPAs. ,, The OPA-OPE pairs, such as tris­(2,4-di- tert -butylphenyl) phosphite (AO168) and tris­(2,4-di- tert -butylphenyl) phosphate (AO168O), bis­(2,4-di- tert -butylphenyl) pentaerythritol diphosphate (AO626) and bis­(2,4-di- tert -butylphenyl) pentaerythritol diphosphate (AO626O2), and trisnonylphenol phosphite (TNPPi) and trisnonylphenol phosphate (TNPP), were indeed well established. Despite their ubiquity in other environmental matrices, ,,− these OPEs were not detected in the wastewater samples.…”

Occurrence of Multiple Classes of Emerging Synthetic Antioxidants, Including p-Phenylenediamines, Diphenylamines, Naphthylamines, Macromolecular Hindered Phenols, and Organophosphites, in Human Milk: Implications for Infant Exposure

“…OPAs represent the most commonly used auxiliary AOs in manufacturing plastics. A representative example is tris­(2,4-di- tert -butylphenyl) phosphite (AO 168), with a yearly output of 23,000 and 56,000 tons in the U.S. and China, respectively. , OPAs were first found in U.S. indoor dust . Recently, a few studies have shown that OPAs, represented by AO 168, also widely occur in outdoor dust, soil, and food contact materials .…”

“…Recently, a few studies have shown that OPAs, represented by AO 168, also widely occur in outdoor dust, soil, and food contact materials . Importantly, OPAs can readily undergo oxidative transformation into organophosphate esters (OPEs), representing an important indirect source of environmental OPEs. , Currently, environmental information on OPAs is limited, and no information is available regarding their toxic effects. In addition to the knowledge gaps in environmental and toxicological data, human exposure to OPAs also remains largely unknown.…”

“…Among three target OPAs, only AO 168 was detected in 24% of the milk samples, with concentrations ranging from <MQL to 484 pg/mL. The detection of AO 168 in human milk can be attributed to its high production volume (56,000 tons per year) in China, 42 which is the highest among all commonly used OPAs. 42 The low DF of AO 168 is a desirable result, because OPAs can be readily oxidized into OPEs in the environment.…”

“…The detection of AO 168 in human milk can be attributed to its high production volume (56,000 tons per year) in China, 42 which is the highest among all commonly used OPAs. 42 The low DF of AO 168 is a desirable result, because OPAs can be readily oxidized into OPEs in the environment. The novel OPEs indirectly formed from the transformation of the OPAs in human milk merit further study.…”