Understanding PFAS Contamination in the Dairy Supply Chain
Per- and polyfluoroalkyl substances (PFAS) are a large group of man-made chemicals used widely in industrial and consumer products due to their resistance to heat, water, and grease. Nicknamed “forever chemicals,” they do not break down naturally and can persist in the environment and human bodies. The pathway for PFAS to enter cheese begins with the dairy cows themselves. These chemicals can contaminate a cow's feed or water supply, particularly in areas near military bases, industrial sites, or where contaminated biosolids (treated sewage sludge) have been used as fertilizer on farm fields. As a result, the cows absorb the chemicals, which can then be transferred into their milk.
How PFAS Gets from Farm to Your Food
- Contaminated Water Sources: Dairy cows drinking water from contaminated wells or surface water sources near industrial or military sites can be exposed to PFAS. Firefighting foams (AFFF) are a well-documented source of contamination around military bases.
- Fertilizer Application: The use of recycled sewage sludge (biosolids) as fertilizer on agricultural land can introduce PFAS into the soil. Crops grown on this soil can absorb the chemicals, and cows consuming this contaminated forage pass the chemicals into their milk.
- Dairy Processing and Packaging: While farm contamination is a major source, PFAS can also potentially enter the food chain during the processing and packaging stages. Some food contact materials, including certain paper and paperboard products, were historically treated with PFAS to make them grease-proof and water-resistant. Though many of these uses have been phased out, the persistence of the chemicals means they can still exist in the food processing environment or leach from older materials.
The Fate of PFAS During Cheese Production
Once PFAS is in the milk, its behavior during cheesemaking is complex. PFAS molecules are amphiphilic, meaning they have both fat-loving (lipophilic) and water-loving (hydrophilic) properties. Studies have shown that during the separation of milk into different components, PFAS distribution is affected by its chain length. Some PFAS variants, particularly long-chain ones like PFOS, can accumulate in the fatty cream, while others, like PFOA, may be found more in the watery, skimmed milk or whey fraction. The European food safety authority (EFSA) and other research have noted that milk cream can contain significantly higher levels of certain PFAS than whole or skimmed milk. This suggests that the type of cheese—full-fat, low-fat, or from whey—may influence the final PFAS concentration.
What do Food Safety Studies Tell Us?
Scientific literature and government testing reveal a varied picture of PFAS in dairy. The FDA's own Total Diet Study has, on several occasions, failed to detect PFAS in tested milk and dairy samples from the general food supply, though critics note their testing sensitivity and sample size may be limited. However, in specific cases where farms were known to be contaminated, testing has revealed concerning levels of PFAS in milk and, consequently, in cheese produced from that milk. A notable case involved a New Mexico dairy farmer who, after discovering his well water was contaminated from a nearby Air Force base, had his milk tested by the FDA, with some samples showing high levels of PFOS. This milk had been used to make cheese, which then entered the food supply. These incidents highlight that while widespread contamination might not be routine, it is a significant risk in geographically specific, contaminated areas.
A Comparison of PFAS Sources in Dairy
| Source of Contamination | Likelihood of Contamination | Impact on Dairy | Mitigation/Prevention | Example |
|---|---|---|---|---|
| Contaminated Water | High, especially near industrial or military sites | PFAS are ingested by cows and enter the milk supply | Strict monitoring and testing of water sources; using alternative, uncontaminated water | Dairy farm near a military base using firefighting foam contaminates the local groundwater |
| Biosolid Fertilizers | Variable, depends on historical and current practices | PFAS is absorbed from soil by crops used for cow feed | Banning the use of sewage sludge on farmland; testing soil before planting | Maine dairy farms contaminated by sludge spread decades ago |
| Food Packaging | Decreasing due to regulations, but legacy issues persist | PFAS can leach from certain grease-proof papers into food during packaging | Use of certified PFAS-free packaging; avoiding recycled materials with unknown history | Cheese wrapped in older-style, PFAS-treated paper can have chemicals migrate to its surface |
| Food Processing Equipment | Low, but possible in specific industrial settings | PFAS-containing components can release chemicals into the food | Use of safer, compliant equipment; rigorous supplier auditing | Non-stick surfaces in equipment used to make processed cheese could be a pathway |
Minimizing Your Risk of PFAS Exposure
For most consumers, the risk of significant PFAS exposure from cheese is low, but it is not zero. Given that the highest risks are localized, the ability to avoid contaminated products can be difficult. These steps can help reduce overall exposure from the food you eat:
- Stay Informed About Local Contamination: Pay attention to local news and environmental health reports, especially if you live near an industrial area or military base with a known history of PFAS use. Some states are taking proactive steps to test for and regulate PFAS in agricultural products.
- Choose Brands That Prioritize Transparency: Look for dairy brands that publicly disclose their commitment to regular water and feed testing and provide clear information about their supply chain. While no federal regulations require this, some brands are taking the initiative.
- Consider Your Cooking Equipment: Avoid non-stick cookware that may contain PFAS. While the risk of PFAS migrating from modern, intact non-stick surfaces is low, any scratching or damage can increase the risk. Opt for stainless steel, cast iron, or ceramic alternatives.
- Filter Your Drinking Water: Since drinking water is a major source of PFAS, using a high-quality water filter (carbon-based filters are most effective) can significantly reduce your intake.
Conclusion
In conclusion, while the presence of PFAS in cheese is not widespread, the potential for localized contamination is a real and documented concern. The primary pathways for PFAS to enter cheese are through contaminated water and feed sources on dairy farms, with lesser risk from packaging and processing equipment. Since PFAS can accumulate in dairy fat, the concentration of the chemical can vary depending on the type of cheese. Until broader, more sensitive testing is implemented across the food supply chain, consumers must remain informed and proactive about reducing their overall exposure to these persistent chemicals. Farmers, producers, and regulatory bodies must continue to work together to mitigate contamination at its source, ultimately ensuring the integrity and safety of dairy products for all consumers.
