Isomeric effects on thiosulfate transformation and detoxification of 1,3-dichloropropene

The fumigant 1,3-dichloropropene (1,3-D) is one of the most heavily used pe sticides but also a suspected carcinogen. Previous research has shown that 1,3-D was rapidly transformed and detoxified by ammonium thiosulfate (ATS), a sulfur and nitrogen fertilizer. As common formulations contain cis and t rans isomers at roughly equivalent ratios, this study was conducted to unde rstand isomeric differences in thiosulfate transformation and detoxificatio n of 1,3-D. Under the same conditions, reaction of cis-1,3-D with thiosulfa te was more than three times faster than trans-1,3-D, which was correlated with a lower reaction activation energy for the cis isomer. The trans isome r was considerably more toxic to the luminescent bacteria Vibrio fisheri th an the cis isomer, but the toxicity was reduced by 14 times after thiosulfa te transformation. Mutagenic activity to strains of Salmonella typhimurium was observed for trans-1,3-D but was not detected after thiosulfate transfo rmation. These results suggest that thio sulfate transformation detoxifies 1,3-D primarily by deactivating the trans isomer, and the reaction is toxic ologically beneficial, as it negates the potential harmful effects of 1,3-D to the environment and human health.