In the recent publication, Zhang et al. (2020) have reported a screening analysis of new persistent and bioaccumulative organic substances unique to China. In this analysis, physicochemical properties and environmental fate (HLa, HLw, and BAF) were estimated using EPI Suite v4.1 if no measured data were available, while the overall persistence (Pov), and transfer efficiency (TE) were calculated using the OECD Pov and LRTP Screening Tool (the OECD tool). All chemicals were screened for the POP-like materials using three indicators: Pov as an indicator of persistence, bioaccumulation factor (BAF) as indicator of bioaccumulation potential, and TE as indicator of long-range transport potential. Substances omitted from the screening included polymers, UVCBs (unknown or variable composition, complex reaction products or biologicals) and organometallies due to limitation of the screening tools. In our opinion, the assessment represents some good progress on the assessment methodology for general chemicals including (l) using the Pov, not medium-specific half-lives, in the persistence evaluation; (2) using bioaccumulation factor (BAF), not just bioconcentration factor (BCF) in the bioaccumulation evaluation; and (3) using deposition potential(e.g., transfer efficiency (TE), not characteristic travel distance (CTD), in long-range transport potential evaluation). By this approach, the uncertainty of the screening results may have been significantly reduced for general chemicals. However, the screening results of organo-silicon compounds are highly uncertain because the tools used to generate physicochemical properties and environmental fate data are not suitable for organosilicon substance as detailed below.
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