Phosphate Ester Flame Retardants in Soils and Rainfall Near a Plastics Recycling Plant.

[NNadir]

I'll post this link to a paper I won't have much time to discuss: Nontarget Identification of Novel Organophosphorus Flame Retardants and Plasticizers in Rainfall Runoffs and Agricultural Soils around a Plastic Recycling Industrial Park Xiaoxiao Li, Yiming Yao, Maosen Zhao, Ji Yang, Yumeng Shi, Hao Yu, Zhipeng Cheng, Hao Chen, Yu Wang, Lei Wang, and Hongwen Sun Environmental Science & Technology 2023 57 (34), 12794-12805.

Plastics recycling is a failure; and this paper suggests that some of the efforts to carry it out have environmental consequences in their own right.

Some text from the paper:

he global production of organophosphate ester (OPE) flame retardants and plasticizers has steadily increased from 300 to 1000 kt over the past decades, (1,2) driven by the phaseout of legacy brominated flame retardants. (3) In 2020, China dominated the market, accounting for 55% of global OPE production at 360 kt. (4) Other organophosphorus flame retardants, including organophosphonates and phosphine oxides, were also produced in China, totaling 235 kt annually. (4) Organophosphate diesters (OPdEs), previously recognized as metabolites of OPEs (mOPEs), also have direct industrial production and applications, exceeding 17 kt annually. (5) Most OPEs are additives rather than chemically bonded to consumer products such as textiles, building materials, and personal care products. Consequently, they are readily released via abrasion, volatilization, diffusion, or leaching, (1,6,7) posing ecological and health risks due to their endocrine-disrupting toxicities. (8–11) Furthermore, the release of OPEs can be expected to intensify during recycling and reprocessing, (12) but the source characteristics of this release remain unknown.
Agricultural soil is a highly concerning reservoir for OPEs as absorption and accumulation of OPEs by crops and vegetables can pose potential ecological and human health risks throughout the food chain. (13–16) Surveys conducted in China revealed Σ11OPEs concentrations ranging from 2.41 to 35.8 ng/g of dry weight (dw) in farmland soil samples from 109 cities. (17) A rather high Σ8OPEs concentration of 136 ng/g dw was reported in agricultural soil in Dalian, China. (18) However, investigations of mOPEs, including OPdEs, OP monoesters (OPmEs), and hydroxylated OPEs (OH-OPEs), in agricultural soils impacted by industry remain scarce. (5,14) Additionally, numerous unknown OPEs released from industrial sources have not been identified. OPEs may not only come from direct input through soil irrigation and amendment but also from precipitation and subsequent carrying effects by runoff from the atmosphere, especially close to point sources. (17,19,20) The process of air or particle-associated emission and subsequent precipitation is of particular concern due to the semivolatile nature of OPEs and their potential to form novel organophosphorus compounds (NOPs). (21)

Plastic recycling is vital for reducing landfill reliance, conserving resources, and protecting the environment from plastic pollution and greenhouse gas emissions. (22,23) However, the process can also produce harmful emissions that need urgent attention. (24,25) Previous studies have primarily focused on the impact of e-waste recycling, (26–28) neglecting plastic recycling activities. Only one study has reported soil contamination from plastic waste disposal, with concentrations of Σ8OPEs reaching 398 ng/g dw in onsite soils and 80 ng/g dw in agricultural soils. (13) Although this concentration was significantly higher than that of nationwide urban and rural soil (Σ19OPEs = 36.6 ng/g dw) in China (29) and farmland soils (Σ12OPEs = 3.91 ng/g dw) in Northern China, (30) it was lower than that of e-waste dismantling site soils (Σ12OPEs = 1.20 × 104 ng/g dw) and surrounding areas (Σ12OPEs = 256 ng/g dw) in South China. (31) Moreover, the concentrations remained below toxic levels, such as tri-n-butyl phosphate (TnBP) at 10,000 ng/g dw, which can cause intestinal damage in earthworms, (32) and tris(1,3-dichloro-2-propyl) phosphate (TDCIPP) at 5000 ng/g dw, which can inhibit the growth and reproduction of earthworms in the soil. (33) However, the potential environmental risks associated with plastic recycling and reprocessing activities remain, as the contamination profiles and underlying risks of mOPEs and unknown NOPs derived from these activities have yet to be clarified.

High-resolution mass spectrometry (HRMS) has been proven to be an effective tool for identifying NOPs in various environmental matrices. Nontarget analysis through HRMS has become an efficient and practical technique to identify NOPs in various environmental matrices. Two aryl-OPEs, namely, 2-biphenylol diphenyl phosphate (2-BPDP) and tris(2-biphenyl) phosphate (TBPBP), initially identified in smartphones, (34) were subsequently detected in indoor dust, soil, wild fish, and sediment from China. (35–38) Tris(2,4-ditert-butylphenyl) phosphate (AO168═O or TDTBPP), a novel OPE derived from its antioxidant precursor, has been reported to be an order of magnitude greater than known OPEs in airborne particulate matter...

...This study investigates the impact of plastic recycling and reprocessing activities on the agricultural environment in northern China. Samples were collected from farmland soil and surface runoff during a rainfall event around one of the largest plastic recycling industrial parks in the area. A total of 28 target OPEs were analyzed to determine their spatial distribution. NOPs and their metabolites were identified through nontargeted analysis using HRMS. The influence of plastic recycling and reprocessing activities on the nearby agricultural environment was evaluated...

A graphic on findings:



The caption:

Figure 2. Spatial distribution of target OPEs and the identified representative NOPs in runoff water (a–d) and agricultural soil (e–i) samples. The data used for the interpolation analysis consist of the individual concentrations of runoff water samples and the means of multiple soil samples collected at each sampling site. Two wind directions were recorded: the northeast wind, which was the instantaneous wind direction during rainfall (sampling), and the southeast wind, which was the prevailing wind direction in the month prior to sampling.

Certain insecticides and indeed chemical weapons feature phosphate esters, which is not to say that any of the above exhibit that kind of toxicity. Nevertheless, I certainly admit to a level of concern, since these can be to my mind isosteres to phosphocholine type phospholipids.

In the conclusion, the authors outline some possible risks:

Literature reports more than 20 OPdEs as contaminants in various environmental matrices or as metabolites of OPEs, associated with developmental toxicity, reproductive toxicity, nephrotoxicity, interference with thyroid homeostasis, and obesity. (5,100,101) Some mOPEs, such as BCIPP and BDCIPP, can be more toxic and persistent than their parent triesters. (102) OPdEs have been detected in wastewater, sludge, and indoor dust, but with limited congeners. The concentrations of BEHP, DPHP, and DBP were up to tens of ppm in sludge and indoor dust and even higher than their respective parent triesters in some areas, possibly due to direct industrial sources.

I'm a "if you have a hammer, every problem is a nail" kind of guy, I guess, but my preferred method of dealing with plastic pollution is through high temperature steam reforming, supercritical water oxidation, and dry reforming. These approaches do not require separation by type of polymer. Under these conditions, mixed plastics can largely be transformed into syn gas.

May you enjoy a productive and successful work week if you work.

[EarnestPutz]

1. Wondered about the environmental impact of syngas and found this quote -

“Renewable syngas will alleviate the exploitation of fossil fuels and make a major contribution to carbon reductions in industry and mobility”. Help me understand how syngas can be “renewable” unless we keep making more plastic, ostensibly from petroleum products. Less carbon dioxide in the air has to be our most immediate goal. Less plastic waste and reducing the resultant threats to health are only fractionally less important. Complicated, isn’t it?