But raw milk drinkers argue that they should be allowed to decide whether to take that risk.
asthma and gastrointestinal issues, although public health agencies and nearly every major medical association in the country say those benefits are unproved.
"It's more than a health issue; it's a human rights issue," said Kathryne Pirtle of Addison, Ill., a professional musician who credits raw milk with eliminating the chronic pain she experienced for 25 years. "Real food and the raw milk movement are the answers to our healthcare crisis and the future of our populations."
The FDA bans interstate sales of raw milk, but states regulate its sale within their borders. Sales are now legal in 27 states under some circumstances, with bills to legalize it pending in Georgia and Wisconsin. In several states, including California, Connecticut and Pennsylvania, raw milk can be sold in retail stores.
In some states, consumers who want raw milk must take their own containers directly to the farm. Another option is a cow share, in which a consumer contracts with a farmer or "milk club" operator to buy a share of the animal. As part-owner, the customer is entitled to some of the cow's milk.
Industry watchers suspect these arrangements may be one reason that federal officials are cracking down on raw milk sales, stepping up efforts to warn consumers of the dangers and urging states to strengthen their regulations.
Keith Parrish and Donna O'Shaugnessy, co-owners of a dairy farm in central Illinois, raised four children on raw milk and are avid proponents of its virtues.
"Consumers have a responsibility to decide what they will put in their mouths," O'Shaughnessy says. "It isn't our goal to convert everyone into drinking raw milk. We're not evangelists. We're just farmers."
From 1998 to 2008, 85 outbreaks of human infections resulting from consumption of raw milk were reported to the federal Centers for Disease Control and Prevention, causing 1,614 illnesses, 187 hospitalizations and two deaths.
The outbreaks — about five per year over the last few years — are due primarily to campylobacter, salmonella and E. coli, according to Robert Tauxe, deputy director of the CDC's food-borne and bacterial diseases division. "We view it as an ongoing problem, one that puts everyone who drinks raw milk at risk," he said.
Drinking contaminated raw milk can cause vomiting, diarrhea and abdominal pain. Most healthy people recover quickly, but the bacteria can be especially harmful for pregnant women, the elderly, children or those with weakened immune systems.
What confounds health officials is the sense that the more they warn against raw milk, the more people seem to want it. In addition to the supposed health benefits, drinking raw milk is seen as a way to support local farmers and bypass the industrial food chain.
"In America we've lost our sense of community, and we're trying to reestablish ties to that which sustains us," said Tim Wightman, founder and president of the Farm-to-Consumers Foundation and the author of the Raw Milk Handbook, a resource guide for farmers. "Raw milk is the gateway; it allows us to begin to question everything we call 'normal.' But this is widely misunderstood by governments and corporations."
Wightman says raw milk drinkers include older farmers, hippies and even doctors who drink it in secret. But health-conscious mothers are the core group pushing sales these days, he said.
Although the exact figure is unknown, an estimated 1% to 3% of milk consumers drink it raw. Many people go to great lengths to procure the controversial drink, which can sell for $4 to $16 a gallon. Some are reluctant to talk about where they get their milk, lest their supplier be shut down.
Raw milk, which fans say tastes like unsweetened vanilla ice cream, is hardly a new phenomenon. People have been gulping it straight from the source since sheep and goats were domesticated in the 8th or 9th century BC. A healthy animal's milk is sterile, but it can be contaminated by an infection in the udder, feces, dirt or unclean processing equipment.
Before pasteurization was instituted in the 1920s, disease outbreaks from raw milk were the No. 1 food safety concern in the country, the CDC's Tauxe said.
A pasteurized debate
Pasteurized milk is heated to a specific temperature for a set period to slow the growth of harmful pathogens. Some enzymes are destroyed, but "the enzymes in raw animal milk are not known to be important in human health," said Dr. Michele Jay-Russell, a veterinarian who is a food safety and security specialist at the Western Institute for Food Safety at UC Davis. "Vitamin C is also reduced by heat treatment, but even raw milk is not a good source of vitamin C."
The FDA and public health experts say there are no "meaningful" nutritional differences between pasteurized and raw milk.
The Weston A. Price Foundation — which advocates for community-supported farms, pasture feeding of livestock and universal access to clean, certified raw milk — disagrees. It also argues that pasteurization has outlived its usefulness.
"Modern stainless steel tanks, milking machines, refrigerated trucks and inspection methods make pasteurization absolutely unnecessary for public protection," its website states.
"Not true," responded Tauxe, who says that the dairy environment is inherently dirty. "Animals and bacteria are natural companions. Normal-looking and -tasting milk from a healthy cow can still be contaminated."
Research supporting the health benefits of raw milk is limited. Proponents often cite a European study that suggests it may have a protective effect against asthma and eczema in children. But the study authors note that other factors might be at play, including the farm environment, and concluded that the risk of pathogens in raw milk outweighs its potential benefits.
Taking a chance
More than three years ago, Mary McGonigle Martin, 51, believed many of the claims she found on the site of the Weston A. Price Foundation. A health-conscious mother who ate organic, she bought some raw milk from a California health food store for her son Chris, then 7.
For two weeks, Chris' chronic congestion eased, she said. But the third week he became violently ill; the milk had been contaminated with E. coli. Chris ultimately developed a serious complication called hemolytic uremic syndrome, marked by prolonged renal failure and pancreatitis. Although he has recovered, he may need a kidney transplant in the future, and the entire family is still shaken, McGonigle Martin said.
"People can drink raw milk their whole life and not get sick," said the Murietta, Calif., mother, who tells her story on realrawmilkfacts.com, a site started by health professionals and researchers. "But the reality is that you don't know when a pathogen is in there. And it's promoted to children and infants, which I think is a crime.
"I support people's right to choose it," she added. "I would never condone it."