I’m not through with my “Illusionist”-driven effort to re-visit milk data. (Don, afraid I’m a little slow on the uptake, so I didn’t figure the ending out till…the end.)
Last month, when I first inquired about the case of Dawn Sharts, New York’s Department of Agriculture and Markets forwarded me a dairy study as “background” . It has the fascinating title, “Prevalence of Salmonellae, Listeria monocytogenes, and Fecal Coliforms in Bulk Tank Milk on US Dairies”, published by the American Dairy Science Association in 2004.
Unfortunately, I only glanced briefly at it when I wrote the BusinessWeek.com article, but in light of the new case involving Lori McGrath, the comments about listeria monocytogenes on this blog, and my re-review of the CDC data yesterday, I decided to read the US Dairies study more carefully. My first reaction was “Yuck!”—from learning that “fecal coliforms” were detected in 818 of 860 bulk tank milk samples, or an astounding 95%. I can’t believe the raw milk currently being consumed around the country would have the same result, without lots of people becoming ill…or perhaps raw milk drinkers have built up amazing immunity?
In any event, there’s lots of pasteurized milk being consumed every day that is, literally, full of poop (even if it’s zapped poop).
More interesting from the perspective of the discussion about listeria monocytogenes were several points in the study. Listeria m was found in 6.5% of the samples, prompting the authors to conclude that “although the prevalence…was low, these pathogens represent a potential risk to consumers of raw milk and raw milk products.”
Obviously, the authors didn’t review the CDC data I reviewed yesterday, showing zero cases of illness from listeria m in raw milk over a period of 32 years. Or, maybe they did, but still felt compelled—perhaps based on not wanting to upset their audience–to talk about “potential risk.”
That little slipup by the authors is enough to call their credibility into question. But there is more to wonder about in the study. The authors mention that in 38 samples showing listeria m, the amount “was below our direct detection limit…” Was there a direct detection limit for listeria m on the New York dairies penalized for having the pathogen? The lab results sent to me for two farms don’t say.
Finally, there’s another statement in the study suggesting the authors’ bias: “Dairy products account for a small percentage of foodborne illness in the U.S., and many of these outbreaks are due to the consumption of raw milk and raw milk products.” Once again, if they had read the CDC data, they’d know raw milk accounted for less than 10% of the total dairy-related outbreaks between 1973 and 2005.
Here’s one statement I can agree with them on: “Public perception of food quality is critical in the marketing of any product.” Thus, if you continually smear one product, public perception should suffer…except if consumers realize who is doing the smearing.
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Note to farmer ed:
If you know more about the situation in Georgia, please let me know (david@davidgumpert.com). There have been recent stirrings in Georgia, including an article in the Atlanta Constitution saying three people got sick from raw milk, and a press release from the state’s director of agriculture warning about the dangers of raw milk.
He was only there four days, but each day he drank non-organic pasteurized milk. By the end of the week he had yellow junk coming out of his nose. His system is so pure, especially after not eating anything for two months and then once he began to eat, at least 90% of the food he consumes is organic.
This food reaction is interesting and Im sure has to do with all the dead bacteria and poop in the milk.
That was a very interesting paper from the American Dairy Science Association. Out of 861 samples, 56 (6.5%) tested positive for L. monocytogenes but only 18 of those samples could be detected by direct plating, indicating a presence of at least 4 cfu/mL. (Colony Forming Units per milliliter.) The remaining 38 samples had to be enriched and incubated for 48 hrs before any Listeria could be found. So, in reality only 2.1% of the samples had directly detectable levels of L. monocytogenes and the remaining 4.4% could only be found by chemically altering the samples.
Mark McAfee has always drawn a distinction between milk produced for pasteurization and milk produced for direct human consumption. The presence of high levels of fecal coliforms in the samples certainly indicates that these bulk tanks most likely contained milk intended for pasteurization! Even so, the contamination rate for the disease-causing Listeria strain is remarkably low. An interesting follow-up study would be to repeat the same tests and procedures on milk samples from dairies producing milk for direct human consumption, such as Organic Pastures or any of the raw milk permit holders in PA or NY.
–"The authors mention that in 38 samples showing listeria m, the amount was below our direct detection limit Was there a direct detection limit for listeria m on the New York dairies penalized for having the pathogen? The lab results sent to me for two farms dont say."–
Under the current FDA guidelines this is actually a moot point since it has adopted a "zero tolerance" policy towards L. monocytogenes. Therefore, detecting any amount of Listeria by any means necessary is grounds for declaring the sample to be contaminated, regardless of whether or not the bacteria could actually produce disease under reasonable conditions. So, finding even 1 cfu/ml by chemically altering the sample and heating it to 90 degress for two days is perfectly reasonable under the FDA guidelines, even though the process bears no resemblance to how the milk is handled in the real world.
The only defense I can imagine is for a farmer to educate his or her customers on the dectection methods and the politics behind the health alerts. A few choice quotes in the local media might also help inform the public and newspaper staff as to the mis-direction and sleight of hand that is really going on.
Then there is the time when a swishing tail delivered a watery shot of poo straight into my open mouth. Skipped the middleman that time!