Which of the following is listed as an environmental source of contaminants in milk?

• A. Feed contamination
• B. Environmental: water, soil, air
• C. Contamination of milking equipment
• D. Direct application to animal or barn

Answer: (B)

Environmental sources cover the broader surroundings of the dairy operation. Water, soil, and air in the farm environment can introduce contaminants into milk through several routes: water used for cleaning or in the cows’ environment can carry bacteria, dust and aerosols in the barn can settle on teats or equipment, and soil or manure particles can be carried into the milking area during barn activity. These pathways reflect contaminants arising from the general environment rather than from what the cow eats, the milking equipment itself, or direct topical applications to the animal or barn. Controlling environmental factors—clean water, good barn hygiene, proper ventilation, and minimizing dust and soil contact—helps reduce contamination before milk is collected and pasteurized.