Toxicologic evaluation of diisopropyl methylphosphonate and dicyclopentadiene in cattle

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Abstract
Diisopropyl methylphosphonate (DIMP), and dicyclopentadiene [3a,4,7,7a-tetrahydro-4,7-methyanoindene] (DCPD), were found as contaminants of groundwater in Colorado. Since there was a potential for cattle to be exposed to these chemicals by drinking well water, a study of their effects was initiated. Eight-to-ten week old calves were given a single dose of either DIMP at 62.5, 125, 250, 500 and 1000 mg/kg of body weight (b.w.) or DCPD at 250, 500, 1000 or 2000 mg/kg of b.w. The calves given DIMP developed tympanitis and ataxia, followed by depression, prostration, and death within two hr after dosing. A slight but significant increase in activated partial thromboplastin time was the only change observed in any of the clinical pathologic parameters. The only gross pathologic changes were acute gastroenteritis with hemorrhages in calves given 1000 mg/kg of b.w. Mild signs of intoxication, ataxia and excess salivation, were observed in calves given 250 mg of DCPD/kg of b.w. At higher doses, these signs were intensified; in addition, calves fell and, while prostrate, exhibited running movements and tonic, clonic spasms. The severity of the signs observed increased as the dose of DCPD increased. All calves given 2000 mg/kg of b.w. and one calf given 1000 mg/kg of b.w. died before seven days after dosing. The only clinical pathologic changes found were increased serum levels of creatine phosphokinase, glutamic-oxalacetic transaminase, and glutamic pyruvic transaminase. The only consistent gross pathologic change was congestion in a variety of tissues in calves given 2000 mg/kg of b.w. A variety of histologic changes were observed in tissues from calves treated with both chemicals. However, these changes were not consistent for any one dose level and were not dose dependent. DIMP was slightly toxic for calves, since no signs of intoxication were observed at doses less than 1000 mg/kg of b.w. DCPD exerted detrimental effects on calves at 250 mg/kg of b.w. and was classified as moderately toxic.