S. Rayne, K. Forest
2011
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Influential Citations
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Journal
Environment international
Abstract
In their article, Zhang et al. (2010) investigate several software prediction methods for equilibrium partition coefficients between octanol and water (Kow), air and water (Kaw), and octanol and air (Koa) in the context of regulatory categorization methods for persistence, bioaccumulation, toxicity, and long range transport potential of various chemicals. The authors use a database of 529 compounds selected from two lists of substances previously identified by Brown and Wania (2008) and Howard and Muir (2010). Our review of the Supplementary materials in Zhang et al. (2010) shows that 18 compounds are duplicate pair structures (given as the following CAS numbers): 2276906 and 13087531; 117964 and 131497 (diatrizoic acid); 20566352 and 77098078 (1,2-benzenedicarboxylic acid, 3,4,5,6tetrabromo-, 2-(2-hydroxyethoxy)ethyl 2-hydroxypropyl ester); 88722 and 1321126 (1-methyl-2-nitrobenzene); 58899 and 319846 (1,2,3,4,5,6-hexachlorocyclohexane); 2176627 and 68412408 (pentachloropyridine); 335671 and 72968388 (octanoic acid, pentadecafluoro[n-PFOA]); 68140181 and 68140192; and 678397 and 68391082 (1-decanol, 3,3,4,4,5,5,6,6,7,7,8,8,9,9,10,10,10heptadecafluoro[8:2-fluorotelomer alcohol]). One of each of these pairs should be removed from the database. As we noted in our previous comparative assessment of various Kow prediction methods for compounds on the Canadian Domestic Substances List (DSL) (Rayne and Forest, 2009), and our investigation into the potential for corresponding false positives/negatives that are dependent on the software employed in regulatory screening frameworks, such databases contain substantial numbers of structural errors and duplication, necessitating rigorous screening. The database in Zhang et al. (2010) contains the following five acid halides: CAS 98099 (benzenesulfonyl chloride); 98599 (p-toluenesulfonyl chloride); 719324; 69116730; and 52314677. Acid halides are extremely reactive toward abiotic hydrolysis, giving the corresponding parent acids in rapid and quantitative yields. Their sensitivity towards atmospheric moisture is also well established from work in synthetic organic chemistry. For example, the International Programme on Chemical Safety (IPCS) Screening Information Dataset (SIDS) document for p-toluenesulfonyl chloride (CAS 98599) states that “[d]ue to the rapid hydrolysis [∼2 min at pH 7] of 4-methylbenzenesulfonyl chloride, water solubility and partition coefficient n-octanol/water cannot be measured.” (http:// www.inchem.org/documents/sids/sids/98599.pdf). As we read the Supplementary materials in Zhang et al. (2010), EPI Suite, SPARC, and ABSOLV flagged this compound as having long range transport potential, and EPI Suite and COSMOtherm flagged it as having bioaccumulation potential in the terrestrial environment. It appears problematic that a regulatory screening system examines compounds for persistency, bioaccumulation, and transport in the environment using computationally generated properties when the literature clearly indicates the compounds are so reactive that the