Distribution, Elimination, and Rearrangement of Cyclic Volatile Methylsiloxanes in Oil-Contaminated Soil of the Shengli Oilfield, China

Abstract

SUBJECT: REVIEW OF TOXICITY INFORMATION ON D5 ______________________________________________________________________________We are forwarding our review of available information on the toxicity and persistence of decamethylcyclopentasiloxane (D5), a proposed alternative for perchloroethylene in dry cleaning. The review was conducted to provide ARB with information on which to base a determination of whether D5 could be considered a non-toxic alternative to perchloroethylene for dry cleaning under AB 998 (Lowenthal, Chapter 821, Statutes of 2003), pursuant to contract number 05-414. In response to your request to evaluate available information on the toxicity of D5 under the statutory mandate, OEHHA staff have reviewed information submitted by the Silicones Environmental Health and Safety Council (SEHSC), including studies evaluating acute and subchronic toxicity, neuroendocrine activity, estrogenicity, genotoxicity, chronic toxicity and carcinogenicity and related mode of action studies, and pharmacokinetics. In addition, we evaluated an SEHSC white paper summarizing the toxicity of D5, and an exposure assessment conducted by Environ Corporation for SEHSC. We also searched the open literature for additional information, including government documents from other countries, and identified additional information on human exposure, environmental persistence and accumulation in biota. As requested by ARB, we focused on evaluating the applicability of the SEHSC-proposed mechanism of action of tumor formation in rodents to human health risk assessment. Our review of the available information is attached.In the process of reviewing the information, we met three times with the SEHSC representatives, including their toxicologists. We sought outside expertise from the University of California, Davis, regarding the merits of the proposed mode of action of D5 induced tumors in rodents. We also spoke with U.S.EPA scientists, who reviewed materials on D5 toxicity under

Occurrence and spatial distribution of neutral perfluoroalkyl substances and cyclic volatile methylsiloxanes in the atmosphere of the Tibetan Plateau

“…These values are 2-3 times and 1-2 orders of magnitude, respectively, higher than those for legacy chemicals (such as DDT and HCHs, with maximum concentrations in the tens of pg m −3 ; Wang et al, 2016b). Moreover, among the various legacy and emerging POPs in wild Tibetan fishes, the average level of PFASs is the third highest (just after those of DDT and HCHs; Shi et al, 2015;Wang et al, 2016a). All this evidence suggests that emerging POPs should be of great concern for the environmental safety of the TP, as they are large-volume-production chemicals that have not been regulated in the surrounding countries.…”

“…With the prohibition of these legacy POPs, their levels in the environment have largely deceased (Hung et al, 2016a, b). Compared with these legacy POPs, other organic substances, such as perfluoroalkyl substances (PFASs) and volatile methylsiloxanes (VMS), have attracted more attention in recent years in the environmental chemistry research community (Pedersen et al, 2016;Shi et al, 2015;D.-G. Wang et al, 2015;Xiao et al, 2015) due to their widespread production, bioaccumulative behaviour, and toxicity. In 2009, perfluorooctanesulfonic acid (PFOS) and perfluorooctane sulfonyl fluoride (POSF) based chemi-cals were listed under Annex B of the restricted substances of the Stockholm Convention (Zushi et al, 2012).…”

Occurrence and Spatial Distribution of the Neutral Per-fluoroalkyl Substances, and Cyclic Volatile Methylsiloxanes in Atmosphere of the Tibetan Plateau

“…These values are 2-3 times and 1-2 orders of magnitude, respectively, higher than those for legacy chemicals (such as DDT and HCHs, with maximum concentrations in the tens of pg/m 3 , Wang et al, 2016b). Moreover, among the various legacy and emerging POPs in wild Tibetan fishes, the average level of ΣPFASs is the third highest (just after those of ΣDDT and ΣHCHs, Shi et al, 2015;Wang et al, 2016a). All this evidence suggests that emerging POPs should be of great concern for the environmental safety of the TP, as they are large volume production chemicals that have not been regulated in the surrounding countries.…”

“…With the prohibition of these legacy POPs, their levels in the environment have largely deceased (Hung et al, 2016a;Hung et al, 2016b). Compared with these legacy POPs, other organic substances, such as per-fluoroalkyl substances (PFASs), and volatile methyl-siloxanes (VMS), have attracted more attention in recent years in the environmental chemistry research community (Pedersen et al, 2016;Shi et al, 2015;Wang et al, 2015a;Xiao et al, 2015) due to their widespread production, bioaccumulative behavior, and toxicity.…”

response to the comments

“…With the prohibition of these legacy POPs, their levels in the environment have largely deceased (Hung et al, 2016a, b). Compared with these legacy POPs, other organic substances, such as perfluoroalkyl substances (PFASs) and volatile methylsiloxanes (VMS), have attracted more attention in recent years in the environmental chemistry research community (Pedersen et al, 2016;Shi et al, 2015;D.-G. Wang et al, 2015;Xiao et al, 2015) due to their widespread production, bioaccumulative behaviour, and toxicity. In 2009, perfluorooctanesulfonic acid (PFOS) and perfluorooctane sulfonyl fluoride (POSF) based chemi-X.…”