Earthworms, not Chemours, the main source of PFAS in Zuid-Holland eggs

Earthworms, and not Chemours, are the main source of the high PFAS concentrations in eggs from hobby chickens in the Zuid-Holland Zuid region, the municipality of Hoeksche Waard reported based on a new study. Eggs laid by hobby chickens in the region contain between 6 and 1,000 times more PFAS than store-bought eggs, so the advice remains not to eat them.

Arcadis, the Omgevigsdienst Zuid-Holland Zuid, GGD Zuid-HOlland Zuid, Tritium Advies, and Wageningen Food Safety Research (WSFR) launched this investigation in October 2023 at the request of the municipalities in the region after reports of high PFAS concentration in hobby eggs. Municipalities like Dordrecht, Molenlanden, Papendrecht, and Sliedrecht wanted to know whether the contamination came from the nearby chemical factory Chemours.

The researchers collected and analyzed eggs at 31 locations and found that they contained significantly elevated PFAS concentrations. They could find no clear link between the PFAS content in the soil and the eggs and, therefore, expanded their research to other possible sources, including various types of feed, water, soil, ground cover, mealworms, earthworms, medicines, and vitamins.

“The research showed that earthworms are an important source of PFAS in eggs,” the researchers concluded. “Chickens eat the worms, which causes PFAS (especially the substance PFOS) to end up in the eggs. The measured quantities in the worms can explain the majority of the PFAS in the eggs.”

“As far as is known, PFOS has never been used in the production process of DuPont/Chemours,” the researchers said. “What the source of PFOS and other PFAS in the living environment is is unclear.”

The RIVM is conducting further research at a national level into the presence of PFAS in eggs.