Originally published in The Weekly Packet, February 2, 2012
Bacteria levels become an issue in the raw milk debate
Testing and requirements explained
by Rich Hewitt
Although the Maine Department of Agriculture’s complaint against East Blue Hill farmer Dan Brown focuses on licensing and inspections, it is a microscopic organism that is behind the state’s licensing and inspection requirements and at the center of the debate over raw milk in Maine and around the country.
Bacteria are everywhere. They live in the soil and on plants in all different types of environments and they live in animals. And they thrive in milk.
Most bacteria are benign and don’t cause problems for humans. But some bacteria can be dangerous to human health, and some are deadly. Concerns over the risks of bacteria in raw milk have prompted many states to prohibit the sale of raw milk, and only 12 states, including Maine, allow its sale.
Milk is an ideal environment for bacteria, according to Al Bushway, a professor of food science at the University of Maine and a food science specialist with the university’s cooperative extension. The pH levels in milk are in the right range and it has the moisture and the nutrients bacteria need to grow. Quickly cooling milk can inhibit the growth of bacteria and chemical treatments can kill bacteria but, according to the Centers for Disease Control and Prevention, pasteurization is the only method used in the U.S. to destroy most of the bacteria in raw milk.
Pasteurization is the process of heating milk to a specified temperature for a specific amount of time. It was introduced in the U.S. in the 1920s and has been used regularly as a way to reduce bacterial contamination in milk since the 1950s.
According to the CDC, there are 31 known foodborne pathogens, as well as other unspecified organisms that can cause illness. According to David Marcincowski, an associate professor of animal science at the University of Maine and an extension dairy specialist, the five major foodborne pathogens are Staphloccoccus, E. coli, Salmonella, Listeria and Campylobactor.
“You can find all five in milk,” he said. “That’s why we pasteurize.”
Most of those bacteria can cause some type of gastric distress in those affected, including cramps, diarrhea and vomiting. According to information on the CDC Web site, most people recover in a week or so, but severe cases can last longer and can cause chronic ailments. The worst cases can result in debilitating diseases and even death.
For example, an outbreak of Listeria in cantaloupe last fall—though not related to raw milk—affected a total of 148 people in 28 states, according to the CDC Web site. Of the 148 affected, there were 30 deaths and one woman who was pregnant at the time had a miscarriage.
The Maine Milk Rule requires that all milk and milk products produced in Maine be tested four times in a six-month period. The Maine Agriculture Department’s Milk Quality Lab in Augusta is charged with testing milk and milk products for the presence of bacteria.
Although the state has set limits for different types of bacteria, it does not test milk or milk products for all potentially dangerous bacteria. The milk quality lab conducts a general aerobic test on milk, which provides a total bacteria count, according to Linda Stahlnecker, the lab’s director. The standard or maximum bacteria count for raw milk that will be pasteurized is 100,000 cfu/ml of milk. For raw milk that will not be pasteurized, the standard is 50,000 cfu/ml of milk. Cfus are “colony forming units,” and each cfu represents the presence of one bacterium in a milliliter of milk.
Although the complaint against Brown did not cite him for exceeding those standards, it noted that tests on milk products from Brown’s farm showed bacteria levels 10 times the standard.
According to Stahlnecker, the lab also conducts a test for coliforms, which is an indicator bacterium that can signify the presence of others.
The standards are considered fairly liberal, and Marcincowski said that most farms maintain levels of 10,000 cfus or less.
“A good, well-managed dairy farm will run between 0 and 1,000,” he said. “The university dairy maintains that pretty regularly.”
Stahlnecker noted that there are about 50 raw milk producers in the state and that the milk from most of those producers tests well under the state’s limits. Some actually meet the standards for milk that has been pasteurized, she said.
When bacteria counts get high, Marcincowski said, inspectors generally will look at four potential causes at the farm: improper cooling, improper cleaning of equipment, a dirty cow, and bacteria or disease in the cow itself.
Despite the bacteria standards, there does not seem to be a threshold count, an established number of a certain bacteria that will make a person sick. Much depends on the type of bacteria, the amount of contamination and the person’s immune defense, which can also affect the severity of the symptoms.
Marcincowski, for example, noted that he grew up on a farm drinking the milk produced there.
“My body adapted to contact with some bacteria levels,” he said. “For someone who had not had that prior experience, there would be more of a risk.”
Generally, according to the CDC, the risk is greater for infants and young children, pregnant women and people with weakened immune systems than it is for healthy school-aged children and adults.