Assessing the Impact of Arsenic on Upper-Midwestern Dairy Operations
Vince Crary, Minnesota Extension, Otter Tail County; Barb Liukkonen, U of M Water Resources Center; Jim Linn, Department of Animal Science, U of M; Mike Murphy, College of Veterinary Medicine, U of M; and Mindy Erickson, Department of Civil Engineering, U of M
If dairy cows drink water containing high levels of arsenic, will milk laced with arsenic end up in cheese, butter, milk and yogurt? A group of Otter Tail County dairy farmers posed this question to their local Extension educator, Vince Crary, back in 2003. When a 1999 Minnesota Department of Health study detected high levels of naturally-occuring arsenic in some domestic wells in western Minnesota, water treatment programs and alternate sources were recommended to families to minimize human exposure to arsenic.But that study didn't answer the dairy question, so Crary called his colleagues at the University of Minnesota (U of M).
The U of M mobilized a multi-disciplinary team of researchers who worked together to secure external funding and design a research protocol. Funding came from the Great Lakes Regional Water Program, as well as from the U of M College of Food, Agricultural, and Natural Resource Sciences' Rapid Response Funds.
Water from over 100 wells in Otter Tail and surrounding counties was sampled. Producers with elevated arsenic levels were invited to participate in the study. Water, feed, and forage were sampled to identify potential sources of arsenic.
In humans, hair, fingernails, urine, and blood are useful indicators of arsenic exposure. No indicators had previously been identified to assess whether cattle exposed to arsenic in drinking water were absorbing it into their systems or experiencing any ill effects from exposure. Hair, hooves, blood, and urine from 5-7 cows on each of the study farms were analyzed for arsenic. Most hair, hoof, and blood samples did not contain arsenic, but arsenic levels in urine correlated well with the level of arsenic in the drinking water supply - making it a good bio-indicator of arsenic exposure.
The research team determined that arsenic does not transfer into milk or cheese, even from cattle exposed to arsenic at 10 times the human drinking water standard.
Well owners were given all the results from their water tests, which included measurements of 27 different constituents (including arsenic, of course). Most owners had never had their well water tested for arsenic and many were very surprised at the results. 51% of the 116 wells tested (in areas where arsenic was expected) had arsenic levels greater than the 10 ppb recommended by the USEPA for safe drinking water.
Several of the farmers installed water treatment units to reduce their exposure to arsenic in drinking water and protect their family’s health.
During 2005 and 2006, the team held five public meetings to inform study participants, other producers, veterinarians and June 12, 2007 was – and is – paramount, yet participants were informed about their own herds throughout the study. Results will be submitted to a peer-reviewed journal in 2007.