How does milk get contaminated?
Milk can get contaminated in these ways:
- Germs from an animal’s poop can get in milk
- Germs from an animal’s skin can get in milk
- Germs in the environment (including the barn and milking equipment) can get in milk
- The dairy animal’s udder can be infected (mastitis)
- The dairy animal can have a disease (for example, bovine tuberculosis)
- Insects, rodents, and other small animals can get in milk
- Conditions in the milk processing plant can be unsanitary
- Cross-contamination from dairy workers can happen—for example, through contact with dirty clothing or boots
Pasteurization can kill germs in milk that can make people very sick.
Does milk have a “built-in” safety mechanism that prevents bacterial contamination?
No. Pasteurization is the best way to get rid of harmful germs in milk and the only method regularly used in the United States.
My farmer tests raw milk, so isn’t it safe?
No. Negative laboratory tests to detect germs in raw milk do not guarantee that raw milk is safe to drink. Tests do not always detect low levels of contamination. People have become very sick from drinking raw milk that came from farms that regularly tested their milk for bacteria.
My farmer uses grass-fed cows and goats to produce raw milk, so isn’t it safe?
No. Outbreaks of illness linked to raw milk have been traced back to both grass-fed and grain-fed animals.
My farmer’s raw milk is organic, so isn’t it safe?
No. Raw milk, regardless of whether it is organic, can contain harmful germs. Pasteurized organic milk is available in many places, including supermarkets, farmers’ markets, and dairies.
Is raw milk at the farmers market safe?
No. No raw milk is safe. Look for pasteurized milk at farmers markets and farm stands.
I’ve heard that many organic and raw milk producers are creating sanitary conditions for raising and milking animals. Does this help reduce milk contamination?
Following good hygiene practices on the farm and during milking can reduce the chance of milk contamination – but not eliminate it.
Illness-causing germs thrive in the environment of dairy farms, even if the farm or barns are kept clean and the farmers are careful when milking. Farmers cannot guarantee that their raw milk and the products made from it are free of harmful germs, even if tests indicate the raw milk does not contain harmful germs.
Can I still get a disease from raw milk and raw milk products if the animals are healthy, clean, and grass-fed or if the dairy is careful and clean when collecting the milk?
Yes. Even healthy animals may carry germs that can contaminate milk. Small numbers of bacteria can multiply and grow in milk from the time it is collected until the time a person drinks it. If the milk is not pasteurized to kill germs, people who drink it can get sick.
Methods for collecting milk have improved over the years but cannot be relied on to be sure milk is safe to drink. Raw milk from “certified,” “organic,” or “local” dairies is not guaranteed to be safe. Pasteurization makes milk safe to drink. You can find pasteurized organic milk and products made from it at many locations.
