Distribution and Emission Estimation of Short- and Medium-Chain Chlorinated Paraffins in Chinese Products through Detection-Based Mass Balancing

Abstract

Short-and medium-chain chlorinated paraffins (SCCPs and MCCPs, respectively) have raised environmental concern due to their potential for persistence, long-range transport, bioaccumulation, and toxicity. However, little is known about the production, use, and environmental emissions of SCCPs and MCCPs in China, the world's largest producer and consumer. In this study, we estimated the amounts of SCCPs and MCCPs produced and used in China in 2018−2019 based on a nationwide survey and measurements of concentrations in products, from which we estimated the environmental emissions of SCCPs and MCCPs in China. Our results show that 225.2 and 236.4 metric kilotons (kt) of SCCPs and 428.5 and 450.2 kt of MCCPs were used in China in 2018 and 2019, respectively, with poly(vinyl chloride) (PVC) products dominating SCCP and MCCP usage. Moreover, a total of 3.9 and 4.2 kt SCCPs and 3.8 and 4.1 kt MCCPs were emitted into China's environment in 2018 and 2019, respectively. Although less MCCPs are released into the air relative to SCCPs, their level exceeds the emission of SCCPs into soil. Finally, detailed mass balance calculation indicates that, although emissions from the use of PVC products dominate SCCP and MCCP inputs into the air, emissions from the use of polyurethane foam adhesives are more closely related to input into surface waters for SCCPs and MCCPs.For input into soil, the main emission sources are the use of polyurethane foam adhesives (for SCCPs) and rubber products (for MCCPs). This study provides a preliminary overview of the distributions of SCCPs and MCCPs in products and insight into the mass balance of SCCPs and MCCPs from their production and use to emission in China. This assessment also provides an important foundation for better understanding the environmental risks and fates associated with SCCPs and MCCPs in China and around the world.

Global Historical Production, Use, In-Use Stocks, and Emissions of Short-, Medium-, and Long-Chain Chlorinated Paraffins

“…Our estimated emissions are comparable to those from previous studies. For example, emissions of SCCPs and MCCPs during production and use in China had previously been estimated to be ∼3900 and ∼3800 t, respectively, in 2018 and ∼4200 and ∼4100 t, respectively, in 2019, whereas we estimated emissions of SCCPs and MCCPs from all lifecycle stages of ∼10,000 and 17,000 t, respectively, in 2018 and ∼10,000 and ∼16,000 t, respectively, in 2019. In addition, the estimated cumulative emissions of SCCPs (∼1.3 Mt) are 6 times higher than the “minimum scenario” estimate by Glüge et al (∼0.227 Mt) since our study (i) filled in data gaps by improving the data of production and use of SCCPs in countries such as Russia, India, and China, which were deemed to be highly uncertain by Glüge et al and (ii) reproduced better time-series data of production and use of SCCPs, especially for period 1950–2000.…”

“…We consider five end-use applications of CPs: (i) use as a plasticizer or flame retardant in PVC products (“PVC products”); (ii) use as a plasticizer or flame retardant in rubber and other plastic products (“rubber products”); (iii) use as an extreme pressure additive and boundary lubricant in metal-working fluids (“metal-working fluids”); (iv) use as a plasticizer or flame retardant in sealants and adhesives (“sealants and adhesives”); and (v) use as a plasticizer or flame retardant in paints and varnishes (“paints and varnishes”). These five end-use applications cover most of the total CP use in individual regions, while only small fractions that are used in other applications (e.g., as fat-liquoring agents in leather treatments), ,, are not considered in this study. Detailed input parameters are introduced in Sections –2.4, and CiP-CAFE’s built-in defaults were used for parameterizations, which were not specified here.…”

“…Emission and waste factors of CPs (SCCP-, MCCP-, and LCCP-specific) are summarized in Tables S5–S8, which take into account four lifecycle processes (i.e., production, industrial processes, instantaneous use, and the use phase or known as the in-use stock) and four waste disposal processes (landfill, wastewater treatment, dumps and simple landfill, and incineration) of CPs. Due to the lack of homologue-specific data, we did not distinguish emission and waste factors among homologues within SCCPs, MCCPs, and LCCPs and thus assigned the factors collected for the technical SCCPs, MCCPs, and LCCPs to all their respective homologues, with the exception of emissions to freshwater and soil from wastewater treatment where homologue-specific emission factors were calculated based on Wang et al When multiple sources were available for a factor, we selected the more conservative estimate as the input to CiP-CAFE since earlier studies , indicated that existing estimates had mostly underestimated the actual emissions.…”

“…However, such information is still missing for MCCPs and LCCPs. Closing this data gap is important because current preliminary information , suggests remarkably different use and emission patterns of MCCPs and LCCPs compared to those of SCCPs. For example, in Western Europe, while SCCPs were mainly applied in metal-working fluids, over 80% of MCCPs were applied in polyvinyl chloride (PVC) products. , Differences in emission patterns can be anticipated as a result of such distinct use patterns: CPs used in metal-working fluids largely end up in industrial wastewater treatment plants, leading to substantial emissions to the aquatic (through wastewater effluents) and soil (through land application of biosolids) environments, while CPs used in PVC products predominately volatilize to air. , Furthermore, there is insufficient information as to the homologue pattern of CP emissions because existing estimates , largely treat technical (SC)­CPs as a whole without considering the region-specific difference in homologous composition.…”

Effects of Pressurized Aeration on the Biodegradation of Short-Chain Chlorinated Paraffins by Escherichia coli Strain 2

“…According to the different carbon chain lengths, CPs can be divided into short-chain chlorinated paraffins (SCCPs, C 10 -C 13 ), middle-chain chlorinated paraffins (MCCPs, C 14 -C 17 ), and long-chain chlorinated paraffins (LCCPs, C 18 -C 30 ) [1]. Due to their excellent flame retardancy, electrical insulation, and low volatility, CPs can generally be used as high-temperature lubricants, plasticizers, flame retardants, adhesives, paints, rubbers, and sealants as additives [2,3]. China is a major producer and exporter of CPs [4], with a total production capacity of 2.08 million tons and an actual output that reached 0.835 million tons in 2018.…”