Page 7 - Spring2008

RAW MILK SAFETY
I have been considering starting on raw milk, but have been unsure as to its safety, so I started some research. These
are my results. All of this is based on data from the CDC and USDA. I’m a scientist by training, so I’m always looking at
data.
On the CDC website we learn that from 1998 to May 2005 CDC identified 45 outbreaks of food-borne illness that
implicated unpasteurized milk or cheese made from unpasteurized milk. These outbreaks accounted for 1,007 illnesses,
104 hospitalizations and two deaths. In most of these reports, raw milk is “implicated,” not “laboratory confirmed.” But
let’s assume all these cases are laboratory confirmed. Making these assumptions, we have about six outbreaks a year,
with 143 people getting sick each year from drinking unpasteurized milk or consuming cheese made from raw milk. This
may seem a very tough sell for raw milk because you can argue that not many people drink raw milk.
The most important piece of data would be the percentage of people who drink raw milk that get sick. I finally did
find this info, in a very roundabout way! I compared this info on raw milk outbreaks to the CDC data on overall food-
borne illnesses. In 2006, 17,252 laboratory-confirmed cases of food-borne infections were counted in a cohort of 15
percent of the US population. Extrapolating from this, we have about 115,103 cases of food-borne illnesses in the US
in 2006 alone, 143 of which came from drinking unpasteurized milk. Note that these are only lab-confirmed cases. Ac-
cording to another CDC website, approximately 76 million Americans suffer from a food-borne illness every year, with
5,000 deaths each year from this cause.
If there are 143 cases of raw milk-borne illness per year compared to a total of 115,103 cases of food-borne illness,
then one-tenth of one percent of all food-borne illnesses, or about one in 800, is due to drinking raw milk.
Still, we need to know what percentage of Americans drink raw milk. If 5 percent drink raw milk, then the percent-
age of illness is very small. If only 1 out of 100,000 drink raw milk, then the percentage of illness is very high. So it is very
important to find these data. . . and I finally did! The data I found for what I wanted were for the pathogen Listeria. Very
interesting information, which also allows me to estimate how many servings of raw milk are consumed in the US per
year! Then I can go back to calculate estimates for the above data.
Here’s the link. Scroll down to page 25, Summary Table 4 at www.fsis.usda.gov/PDF/Slides_092806_JSofos.pdf. This
table gives total cases of Listeria in the US as well as their food source. Most interestingly, it estimates the total number
of cases per serving of that food eaten. This is the data I wanted. As we can see, unpasteurized milk is actually the fourth
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highest risk for Listeria illness, with 7.1 x 10 illnesses per serving. However, take note that the highest risk is deli meats,
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which have ten times the rate of Listeria illness per food serving, at 7.7 x 10 .
To put that in perspective, for every serving of deli meat you eat, you have ten times greater risk of getting sick from
Listeria than from drinking a glass of raw milk. Smoked seafood (like lox) and precooked shrimp have about the same
rate as raw fluid milk.
Now, from this data, I can also calculate how many servings of raw milk are served per year in the US. There were
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3.1 cases of Listeria from drinking raw milk per year, according to that chart. There also were 7.1 x 10 illnesses per serv-
ing. From this I can reverse calculate that the USDA estimates that there are a total of 437 million servings of raw milk
consumed in the US per year. I can also calculate that there are about nine billion servings of pasteurized milk drunk in
the US per year. That is 20 times the number of servings of raw milk, which leads me to conclude about 5 percent of
the population, more or less, drinks raw milk, and 95 percent drinks pasteurized.
Out of a total of 437 million servings of raw milk in the US per year, 137 people got some sort of illness. On a per
serving basis, that is 3.18 x 10 . That means you would have to drink 3.18 million glasses of raw milk before you might
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expect to get an illness of any kind due to that milk. (Actually, you’d have to consume far more glasses than that, because
those 137 illnesses also included raw cheese, not just raw milk.)
Just to give some further perspective, 16.5 percent of all broiler chickens tested by the FDA in 2006 contained sal-
monella bacteria. The rate of human salmonellosis in the US was 14.7 cases per 100,000 people in 2004. This is 4200
cases per year. Since 16 percent of the poultry have confirmed salmonella bacteria in them, one might assume that a lot
of those cases come from eating chicken. But we don’t hear a big uproar about that, do we? The USDA hasn’t banned
people from eating chicken.
Greg Bravo
San Francisco, California

When you look at the statistics carefully, you find that virtually all of the Listeria cases from raw milk products occurred in
so-called raw soft cheeses. It is impossible to tell whether these cheeses are in fact made from raw milk because the test
for lack of pasteurization is based on the presence of the enzyme phosphatase, which is produced by cheese bacteria.
In any event, confirmed cases of Listeria from raw fluid milk are essentially nonexistent.

SPRING 2008 Wise Traditions 7