As the debate about the health attributes and risks of raw milk spills into capitols and courts across the country, a food-safety expert in Penn State's College of Agricultural Sciences is urging people to think carefully about the risks before consuming unpasteurized dairy products.

Pushing to make it easier for consumers to buy unpasteurized dairy products, proponents of raw milk claim that pasteurization -- the process of heating milk to destroy bacteria and extend shelf life -- destroys important nutrients and enzymes. The introduction of laws and lawsuits is leading to confusion.

"There is a lot of misinformation circulating about raw milk, but we recognize people's right to consume the foods that they want," said Kerry Kaylegian, director of industrial outreach for the university's Department of Food Science. "We are advising people to be cautious because we know that raw milk can carry an increased risk for bacterial contamination that can lead to illness and even death."

The issue recently made headlines in Pennsylvania when raw milk sales were suspended at two dairy farms in Centre and Clinton counties after random state checks revealed pathogen problems, underscoring concerns about the safety of unpasteurized milk.

"More than 1,500 people became ill from drinking raw milk between 1993 and 2006, according to the most recent data available from the Centers for Disease Control and Prevention," Kaylegian said. "Of those, 185 were hospitalized and two died. And the CDC said not all foodborne illnesses are reported, meaning the actual number likely is higher.

"Consuming raw milk is particularly dangerous for pregnant women, children, the elderly and people with weakened immune systems."

Some people want to drink raw milk for a variety of reasons, Kaylegian noted, including perceived health benefits, flavor, the desire to increase their connection with local food producers and the desire to consume less-processed foods.

To accommodate such consumers and dairy producers who want to supply them, Penn State Cooperative Extension dairy scientists offer educational programs for raw-milk providers, encouraging them to concentrate on farm sanitation, milk cooling, animal health and regular testing of milk.

Kaylegian pointed out that the sale of raw milk for human consumption in the Keystone State is limited to dairies with raw-milk permits issued by the Pennsylvania Department of Agriculture. But the state has more dairy operations licensed to sell raw, unpasteurized milk than any state in the nation.

"Permitted raw-milk dairies are evaluated by a milk sanitarian from the Agriculture Department," Kaylegian explained. "Essentially, the purpose of the farm evaluation is to assess farm cleanliness, animal health and potential food safety. Specifically, the milk sanitarian inspects the dairy farm using a risk-assessment checklist to make sure the dairy producer is following procedures in the Milk Sanitation Law.

"In addition, milk samples will be tested for hygiene, animal health and the presence of disease-causing bacteria," she said. "The intention of the law is to protect consumers from getting sick from consuming unpasteurized milk products."

Kaylegian suggested that many consumers aren't aware of the danger and that the rising popularity of unpasteurized milk has obscured the risks that come with consuming it. "A lot of people don’t realize that milk is a potentially hazardous food," she said. "Actually, most raw animal products do have a pathogen risk to them -- which is why we traditionally cook beef, eggs and poultry. Milk falls into that category."

Farms selling raw milk are tested twice a year for pathogens, but occurrence of pathogens in raw milk is sporadic, Kaylegian warned. "So just because a test last month came back negative doesn't mean your milk is pathogen-free," she said. "It is to your advantage to know as much as possible about your farmer and his or her sanitation practices."

The sale of raw milk is prohibited in 23 states, although seven of them let people get milk through so-called herdshare programs, in which customers can buy ownership in a cow in return for raw milk from the animal. Retail sales of raw milk is allowed in eight other states besides Pennsylvania, and 18 other states, like Pennsylvania, allow the sale of raw milk from a farm directly to an individual.

The controversy about the consumption of raw milk is intensifying across the country. Lawmakers in seven states -- Georgia, Iowa, Missouri, New Jersey, North Dakota, Wisconsin and Wyoming -- recently have introduced measures seeking to change laws governing raw milk. The Virginia-based Farmer to Consumer Legal Defense Fund also has filed lawsuits in California, Iowa, Missouri, New York and Wisconsin challenging various aspects of states' laws regarding raw milk.

"With raw milk, the concern is that it can be contaminated and that it provides a good environment for bacteria to grow to high levels, which increases the chance it can make people sick,'' said Kaylegian. She noted that the U.S. Food and Drug Administration and the Centers for Disease Control and Prevention support pasteurization. "The position of those organizations is that the process doesn't significantly change the nutritional content of milk," she said.

Consumption of dairy products (yogurt and cheese) can be traced back 8,500 years. For most of history, the world was an agrarian society in which milk was produced in small herds on family farms. In the mid-1800s there was a shift from agrarian to urban societies, and in the early 1900s milk consumption was found to be associated with diphtheria, tuberculosis, brucella and typhoid.

"In 1938, 25 percent of foodborne-illness outbreaks were traced to dairy products," said Kaylegian. "The pasteurization process was applied to milk for the purpose of killing pathogens. Pasteurization conditions were adopted in 1939 that were sufficient to destroy Mycobacterium tuberculosis, the most heat-resistant pathogen known at the time."

"In 1956, pasteurization conditions (time, temperature) were increased to destroy Coxiella burnetii, which causes Q-fever. Pasteurization was adopted nationwide in the United States in 1958."