Hazardous chemical residues in milk and dairy products present a public health concern, especially to children who are considered most vulnerable to many of the adverse developmental effects attributed to these compounds. The dairy industry has historically been instrumental in the efforts to standardize and implement production quality systems in response to microbial and sanitation concerns. However, food safety concerns extend well beyond microbiological hazards. The wider recognition of chemical hazards in milk and dairy products demand a more complex assessment of possible food safety issues to develop a scientific-based approach to exposure risks. Regular monitoring and risk assessment efforts for chemical hazards are needed; currently, those efforts vary greatly by country and geographic regions because of the high costs for testing, the need for advanced technologies, the lack of and/or differing maximum residue levels, the different use patterns of chemicals, the political climate, and the different environmental conditions. Overall, there are limited surveillance data available to estimate human intake of chemicals of concern through milk and dairy products. The few studies that examine the transport of chemicals from air and soil to forage and transfer into milk and dairy products focus primarily on persistent organic pollutants including PCBs, dioxins/furans, and some pesticides. Continued research is needed to offer insight into transfer of chemicals through food webs and to expand surveillance for residues to a broader range of chemicals.

Used in both beef cattle and dairy cows, monensin can provide many health benefits but can, when unintended overexposures occur, result in adverse effects. Information on serum and tissue concentrations following overexposure and/or overt toxicosis which may aid in diagnostics and clinical outcome is lacking. The aim of this study was to determine concentrations of monensin in biological specimens following oral exposure for 10 days to an approved dose (1 mg/kg) and a higher dose (5 mg/kg) of monensin given daily on a body weight basis to 10 dairy cows. No deaths were reported; cows receiving 5 mg/kg showed early signs of toxicosis including depression, decreased feed intake, and diarrhea after 4 days of exposure. Histopathological findings were minimal in most cows. Pharmacokinetic modeling of the detected serum concentrations for the 1 and 5 mg/kg dose groups determined the Cmax , Tmax, and t1/2λ to be 0.87 and 1.68 ng/mL, 2.0 and 1.0 h, and 1.76 and 2.32 days, respectively. Mixed regression models showed that the dose level and days since last dose were significantly associated with monensin concentrations in all four tissues, and with cardiac troponin levels. The high dose resulted in a significant elevation of monensin in tissues at approximately 4.7 times compared to the monensin concentrations in the tissues of animals from the low-dose group. The cTnI concentrations in the high-dose group were 2.1 times that of cTnI in the low-dose group. Thus, the ability to diagnose monensin overexposure and/or toxicosis will improve from knowledge of biological monensin concentrations from this study.

Large-scale toxic events on dairies can be difficult emotionally and financially. Many diseases of animals manifest over predicable time frames, whereas toxic events can appear quite suddenly and unexpectedly. Severity of toxic signs can range from non-clinical to clinical. Mortality rates can vary, but in today's concentrated animal feeding units high mortalities can be quite devastating. In addition to the potential disruption of milk shipped and cows lost, a toxic event also presents a possible food safety and public health issue that potentially erodes consumer confidence. Quick and accurate assessment of a toxic event is crucial for the health of both the animals and people consuming products derived from affected animals. The objective of this paper is to describe a smartphone or tablet application (app) that can be downloaded to assist field personnel investigating a toxic event.

Within an hour of the planned feeding of a group of 300 Holstein cattle, a large number of cattle developed tremors, diarrhea, weakness, and paralysis. All cows exposed to the feed, a total of 159, died within 24 hours despite treatment attempts with atropine in approximately 100 animals. An additional 8 exposed animals were culled within a week. A thorough investigation demonstrated the accidental mixing of phorate into the total mixed ration instead of the intended mineral mix. Diagnostics confirming phorate exposure in deceased animals included brain cholinesterase determinations and the analysis of liver, rumen content, milk, and feed for phorate. Phorate is a restricted-use organophosphorus pesticide commonly used in US agriculture because of target pest efficacy, cost, and availability. Even with known human, animal, and ecological risks, organophosphorus pesticides remain the most widely used insecticides in the world today. This necessitates awareness about how to identify pesticide exposure in food animals and the corresponding public health risks for humans, including the potential for meat and milk residues and exposure in children. This report describes a dairy’s catastrophic loss of 167 cows caused by human error and assesses the public health implications therein. Veterinary diagnosticians, public health officials, and veterinarians must be prepared to collaborate in order to advise clients on case work-up, management, and preventive measures.