Chlorinated hydrocarbon and arsenic poisoning in cattle
By Travis Mays, Analytical Chemistry Section Head
A herd of 14, six-month-old crossbred cattle was turned out into a new pasture. Within five days, five head died suddenly. An old barn with various abandoned and discarded metal and equipment was noted to be in the pasture. Chemical poisoning of an unknown origin was suspected. A 500-pound steer was submitted to the Texas A&M Veterinary Medical Diagnostic Laboratory (TVMDL) in College Station for necropsy. The animal was noted to be in good body condition. No gross lesions were observed during the necropsy. Rumen content and fresh liver were collected and submitted to the toxicology section for chemical analysis.
A comprehensive metals profile was performed on the fresh liver using inductively coupled plasma mass spectrometry (ICP-MS). A toxic amount of arsenic (77.66 micrograms per gram dry weight) was measured in the liver by ICP-MS. Further testing to identify the source of the arsenic (organic vs. inorganic) was not pursued. A toxic chemical screen was performed on the rumen content using gas chromatography – mass spectrometry (GC-MS). Heptachlor, chlordane, and nonachlor were all detected in the rumen content by GC-MS.
Arsenic is a metalloid with many applications, including rodenticides, insecticides, herbicides, and fungicides, the latter found in some treated lumber. However, these applications are declining due to the toxicity of arsenic and its compounds. Most cases received by TVMDL involving arsenic are the result of exposure to both organic and inorganic forms, historically used as poisons and herbicides, that are not properly disposed of, resulting in inadvertent exposure. Examples of inorganic arsenic include Paris Green and calcium arsenate. Examples of organic arsenical compounds used in agriculture include monosodium methyl arsenate (MSMA) and disodium methyl arsenate (DSMA). Arsenic can be detected by ICP-MS in a variety of samples including liver, kidney, urine, whole blood (EDTA or heparinized), and rumen content. A qualitative Reinsch test can also be performed on rumen content, source material, and soil to determine if the arsenic source is organic or inorganic.
Chlordane is a mixture of closely related chlorinated hydrocarbon compounds, including heptachlor and nonachlor, that was historically used as a pesticide for corn and citrus crops, and termite control. Chlordane was banned by the EPA in 1983, except for termite control in wooden structures. The EPA banned this remaining use of chlordane in 1988. Chlorinated hydrocarbons are best detected in rumen content or liver using GC-MS. Chlorinated hydrocarbons can also be detected in non-biological samples, such as water and soil using GC-MS.
Many losses can be avoided by examining old buildings or disposal areas for harmful chemicals before turning animals out. TVMDL can perform testing on unknown or unlabeled chemicals for identification purposes.
For more information about this case, contact Travis Mays, analytical chemistry section head. To learn more about TVMDL’s testing services, visit tvmdl.tamu.edu or call 1.888.646.5623.