Raw Milk Found to Contain Harmful Bacteria

Tuesday, 10 March 2015

A report published today by the Food Safety Authority of Ireland (FSAI) shows that raw milk can contain harmful bacteria and therefore, the consumption of raw (unpasteurised) milk increases the risk of developing foodborne illness.  The FSAI continues to recommend that the sale of raw milk for direct human consumption should be prohibited in Ireland and advises that the most effective way to protect public health is to ensure that all milk is effectively heat-treated (e.g. pasteurised or boiled), especially when served to infants, children, pregnant women, older people and those with a weakened immune system or those suffering from a chronic disease.

The report details the results of an FSAI microbiological survey confirming the presence of pathogens in raw milk and the in-line filters used in the milking equipment.  For raw milk samples, detection rates of Listeria monocytogenes and Campylobacter were 7% and 3%, respectively.  However, detection rates in milk filter samples were considerably higher at 20% and 22% respectively, which suggests a greater potential for contamination of raw milk.  In addition, Salmonella was detected in 1% of raw milk filters and 0.5% of raw milk samples, while E. coli O26 (VTEC) was detected in 6% of raw milk filter samples showing its potential to contaminate raw milk.

Dr Wayne Anderson, Director of Food Science and Standards, FSAI, states: “Almost all milk on sale in Ireland is pasteurised and pasteurisation is the simplest and most reliable method to ensure that milk is safe to drink.  While the market for raw milk is small, it remains a serious concern given the well-documented public health risks posed by the presence of pathogens in raw milk.  We are therefore recommending that raw milk should be avoided by consumers, but for those who still wish to drink it, they should, at a minimum, boil the milk before drinking it to kill any potentially harmful bacteria.”

Commenting on the ongoing risk to farm families who continue to consume raw milk in their own homes, Dr Anderson states: “The FSAI is aware that any ban on the sale of raw milk would not affect those farm families who choose to consume raw milk.  But farm families should be particularly aware of the risk to young children and pregnant women posed by drinking raw milk and also the fact that farm visitors may not be aware that they are consuming raw milk. We therefore continue to recommend the use of home pasteurisers to ensure milk is safe.” 

Dr Anderson notes that, while on-farm hygiene and animal health on Irish farms have improved immensely over recent years, farms remain a significant reservoir for pathogens. Even under the best hygiene standards, it is possible that raw milk can become contaminated. Improving on-farm sanitation and hygiene will improve the quality of raw milk but will not always guarantee safety.


Note to Editor:

Glossary of terms:

• A bulk tank is a large stainless steel storage tank used for cooling and holding raw milk. It serves the purpose of agitating and storing the milk on the farm and maintaining it at an appropriate temperature until the milk is collected for transportation to the milk processing plant.

• A milk filter serves the purpose of filtering large particulate debris, e.g. faeces, soil, bedding and feed particles that may inadvertently enter milk from the milking process. The filter is usually placed in the milk pipeline, which transports the milk from the animal to the bulk tank. The filter is not fine enough to remove bacteria from the raw milk.

• Pasteurisation is a process of heating raw milk to a specific temperature for a pre-defined length of time (at least 72°C for 15 seconds or equivalent) and then immediately cooling it after it is removed from the heat. This process results in the destruction of harmful microorganisms and slows spoilage due to microbial growth in the food.

• Raw milk means any milk produced by the secretion of the mammary gland of farmed animals that has not been heated to more than 40oC or undergone any treatment that has an equivalent effect

Raw Milk and Raw Milk Filter Microbiological Surveillance Programme