In 2007 and 2008 there were two foodborne disease outbreaks attributed to milk in New England. In January 2008, Massachusetts public health officials announced that Listeria monocytogenes was found in the Shrewsbury milk plant implicated in the deaths of three elderly men and the illness and miscarriage of a 30 year old woman since June of 2007. The milk was pasteurized. Samples of the milk contained the bacteria that made people sick. It is likely that contamination occurred after the pasteurization process. As a result of the outbreak, the milk plant closed down.
Then, in August 2008, seven people became ill from E. coli O157:H7 after drinking raw milk from a Simsbury, Connecticut dairy (other unconfirmed, but likely linked, cases also were noted). Testing by the Connecticut Department of Agriculture found the strain of E. coli that caused the illness in the feces of one cow. None of the milk samples tested positive.
These outbreaks add fuel to both sides of the debate that is raging all over the country regarding whether raw milk should be available to those who want to buy it. Is raw milk safe to drink? How can pasteurized milk be implicated in a foodborne disease outbreak—isn’t pasteurization supposed to make it safe?
Among dairy product-associated outbreaks reported to CDC between 1973 and 2009 in which the investigators reported whether the product was pasteurized or raw, 82% were due to raw milk or cheese. From 1998 through 2009, 93 outbreaks due to consumption of raw milk or raw milk products were reported to CDC. These resulted in 1,837 illnesses, 195 hospitalizations, and 2 deaths. Most of these illnesses were caused by Escherichia coli O157, Campylobacter, or Salmonella. It is important to note that a substantial proportion of the raw milk-associated disease burden falls on children; among the 93 raw dairy product outbreaks from 1998 to 2009, 79% involved at least one person less than 20 years old.
Regulation and pasteurization
Prior to the 20th century, it was estimated that 25% of all food and water borne diseases were related to the consumption of milk. Studies regarding the role of milk and the spread of disease at that time indicated that in order to control milkborne diseases, there would need to be in place sanitation measures that addressed the safety of milk during production, handling, pasteurization and distribution of milk and milk products. In 1924, the United States Public Health Service (USPHS) developed the Standard Milk Ordinance, which was not a regulation, but guidance, and encouraged states to adopt it. This ordinance has been through several iterations and is now known as the Grade “A” Pasteurized Milk Ordinance; the most recent version being published in 2003. Most states, including Connecticut, have adopted this ordinance as their method of regulation of dairy products.
It wasn’t until 1973 that the United States Food and Drug Administration (FDA) banned interstate sales of unpasteurized or raw milk. At that time if the raw milk was “certified,” its sales were still permitted across state lines. That ended in September of 1987.
However, states are still free to make their own regulations regarding the sale of raw milk within their borders. Presently there are 28 states that allow the sale of raw milk either through retail sales or on-farm sales, including Connecticut.
Connecticut regulations
In Connecticut, those who choose to drink raw milk may purchase raw milk at farms, dairy stores and retail operations in this state. The Connecticut Department of Agriculture (DoAg) regulates the dairy industry in Connecticut. Producers of raw milk and raw milk cheese (called retail raw milk and retail raw milk cheese) must register with the CT DoAg and obtain a permit to operate. The regulation also states that the “Milk Regulation Board shall adopt regulations, in accordance with the provisions of chapter 54, establishing standards for sanitation, production, sale, labeling, handling and storage of retail raw milk and the manufacture of raw milk cheeses.”
In addition, inspections are performed regularly and include quarterly pathogen testing for Listeria monocytogenes, Salmonella species, E. coli O157:H7 and Campylobacter jejuni. Monthly tests are performed for coliform bacteria (indicators of fecal contamination) and other indicator bacteria to assess biological quality of the milk. If coliform bacteria counts are greater than 150/ml, an immediate regulatory response will result; if greater than 50, but less than 150, a warning letter is given. If there is a second coliform count greater than 50 within 6 months, regulatory action will result.
Dairy products can be risky foods:
Milk is produced by animals, including cows, goats and sheep. Like other foods from animal sources (meat, poultry, and eggs), dairy foods have the potential to be a source of the microorganisms that cause foodborne illness. These foods come from animals that may harbor pathogenic, or "sick-making," organisms, including bacteria, viruses and parasites. These organisms may be present in the farm environment, barn, manure or food (forage).
Most milk is pasteurized before it is sold as liquid milk, or before being made into cheese or ice cream. During pasteurization, raw milk is heated while being shaken so that every particle of milk, including the foam, reaches a temperature of 145°F. It is then held at 145° F for 30 minutes. Or, processors may heat milk to 161°F and hold for 30 seconds. The heating process destroys the pathogenic microorganisms that cause foodborne illness.
Pasteurized milk and dairy products made from pasteurized milk are considered to be free of pathogenic microorganisms. But, it is still possible for pasteurized milk to be the source of a foodborne disease outbreak like the one in Massachusetts in January. If not handled safely, pathogenic microorganisms may contaminate the dairy products at some point—perhaps when bottling or capping--after the pasteurization process.
Artisanal or farmstead cheeses are cheeses that are made on the same farm that produces the milk-bearing cow, sheep or goat. If the milk used to make the cheese is not heat treated, it is possible that the raw milk cheese made can be contaminated with the same pathogenic organisms that may be found in raw milk. Most states and the Federal Food Code only allow raw milk cheeses that have been aged for 60 days to be sold. The aging process is thought to destroy pathogenic organisms over time. However, that has been called into question recently and research is being conducted to determine the likelihood that pathogenic microorganisms will survive the aging period.
Unpasteurized dairy products are especially risky when consumed by people at greater risk for foodborne illness. Infants, young children, pregnant women, the elderly and those with chronic illnesses are all likely to have immune systems that may not be able to protect them from the pathogenic microorganisms that could contaminate raw milk or some raw milk cheeses. These folks should choose pasteurized dairy products.
Making your decision
In Connecticut, you are still able to make up your own mind about whether you want to drink raw milk or eat raw milk cheeses. Some folks insist that pasteurization destroys health promoting properties of raw milk, including beneficial bacteria, enzymes and proteins. But others dispute these claims. The Weston Price Foundation website, realmilk.com, contains information about the benefits of raw milk; rebuttals to the argument that raw milk should not be produced for human consumption, and sources of raw milk. One goal of the Foundation is, “the establishment of universal access to clean, certified raw milk.”
When consumers are allowed to make their own choices about the food they eat (ie. the consumption of raw clams and oysters is legal in all states, though some health authorities require a warning label on the menu), they must make these choices based on information available at the time regarding the risk of these decisions.
Want to read more?
Centers for Disease Control (CDC) Raw milk questions and answers
US Food and Drug Administration (FDA): The Dangers of Raw Milk