Fate, Metabolism, and Toxicity of 3‐isopropyl‐1H‐2,1,3‐benzothiadiazin‐4(3H)‐1‐2,2‐dioxide in a Model Ecosystem

Abstract

Abstract Bentazon, (3‐isopropyl‐1H‐2,1,3‐benzothiadiazin‐4(3H)‐1‐2,2‐dioxide) a new experimental herbicide, was studied in a model ecosystem. The radioactivity could not be ether extracted from the water until the solution was acidified with HCl. We believe that HCl may be either releasing the parent material from conjugates or that it simply needs acidification before it can be extracted. The major metabolite found in the water was N‐isopropyl anthranilic acid amide, but bentazon was also present in significant amounts. A fresh water crab ( Uca minax ) contained anthranilic acid, N‐isopropyl anthranilic acid, and bentazon. The aquatic organisms did not accumulate the chemical to any significant degree, although the fresh water crab accumulated it 50 times over the amount found in the water. This was not considered large when compared to DDT. This compound generally does not pose a threat to aquatic food chains on the basis of toxicity nor metabolism results. These data are the first to be published on an experimental herbicide and suggest that the model ecosystem can be used as a tool for routine evaluation of herbicide biodegradability.