But raw milk drinkers argue that they should be allowed to decide whether to take that risk.
Many who drink raw milk believe that the unprocessed, non-homogenized version is more nutritious and that it can ease ailments such as allergies, 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.