Consumers can't always tell if bacteria levels in raw milk products such as cheese are dangerous by smelling or tasting them, says the U.S. Centers for Disease Control and Prevention. (Associated Press)The rate of disease outbreaks caused by raw milk and related products was 150 times greater than outbreaks linked to pasteurized milk during a 13-year period, according to a study by the U.S. Centers for Disease Control and Prevention.

The review, published in the Atlanta-based CDC's Emerging Infectious Diseases journal on Tuesday, also found that states where the sale of raw milk was legal had more than twice the rate of outbreaks as states where it was illegal.

“While some people think that raw milk has more health benefits than pasteurized milk, this study shows that raw milk has great risks, especially for children, who experience more severe illnesses if they get sick,” said study co-author Dr. Barbara Mahon in a release. "Parents who have lived through the experience of watching their child fight for their life after drinking raw milk now say that it’s just not worth the risk.”

The study reviewed outbreaks of dairy products such as milk, cheese and yogurt from 1993 to 2006 in 50 states. It compared the amount of milk produced in the United States during the study period to the amount that CDC estimated was likely consumed raw (about one per cent) to determine the 150-times-higher rate for outbreaks caused by raw milk products.

The study included 121 dairy–related disease outbreaks, which caused 4,413 illnesses, 239 hospitalizations and three deaths. In 60 per cent of the outbreaks, state health officials determined raw milk products were the cause.

Nearly all of the hospitalizations (200 of 239) were in those who became sick during the raw milk outbreaks, which occurred in 30 states. Seventy-five per cent, or 55, of the raw milk outbreaks occurred in the 21 states where it was legal to sell raw milk products at the time. The study also noted seven states changed their laws during the study period.

CDC recommends restricting raw milk sales

The CDC says looking at, smelling or tasting raw milk won't signal if it's safe to consume. It adds that even under ideal conditions of cleanliness, collecting milk introduces some bacteria and that without pasteurization — heating milk to extreme temperatures — bacteria can multiply and grow.

"Pasteurization is the most reliable and feasible way to render dairy products safe for consumption," the study concludes. "Although warning labels and signs or government-issued permits are prudent where the sale of non-pasteurized dairy products is legal, they have not been shown to be effective and, given the results of this analysis, do not seem to reduce the incidence of outbreaks involving non-pasteurized dairy products to the degree that pasteurization does."Ontario farmer Michael Schmidt was found guilty last year of contravening a law against selling raw milk, and fined $9,150. (Colin Perkel/Canadian Press)

In the CDC news release, Dr. Robert Tauxe, deputy director of CDC's division of food-borne, water-borne and environmental diseases division, said restricting the sale of raw milk products "is likely to reduce the number of outbreaks and can help keep people healthier."

In recent years, the issue of raw milk safety has arisen in other countries as well, with some organizations arguing raw milk can be produced hygienically, and it has health benefits that are destroyed when it's pasteurized.

In Canada, while it's legal to drink unpasteurized milk, selling it is against the law because of the risk of food-borne diseases

In September, the Ontario Court of Justice found Durham dairy farmer Michael Schmidt guilty on 15 of 19 charges of selling and distributing raw milk. The decision overturned a January 2010 acquittal of all 19 charges by Justice of the Peace Paul Kowarsky.

In November, Schmidt was fined $9,150.