In May 2012, the Vermont Department of Health, Agency of Agriculture, Food & Markets, and the federal Agency of Toxic Substances and Disease Registry (ATSDR) conducted a study to determine if formaldehyde from used foot baths emptied into manure pits adds to public exposure when that manure is spread on farm fields.
Two sites (farm houses and properties in East Berkshire and Fairfax) were tested for both outdoor and indoor levels of formaldehyde in the air. Indoor air measurements ranged from 4.2 to 47 parts per billion, consistent with indoor air levels measured in nationwide studies. Outdoor air measurements were mostly below the detection limit; three detections ranged from 4 to 5.7 parts per billion, consistent with outdoor air levels measured in nationwide studies. Only one detection occurred on a day that manure was spread.
Manure was sampled just prior to spreading. Samples were taken from farms that use formaldehyde foot baths and from several that do not. Similar measurements of formaldehyde were detected in manure from farms that used and did not use formaldehyde foot baths.
There was no evidence that the spreading of manure from farms that use formaldehyde foot baths influenced either indoor or outdoor air concentrations of formaldehyde as compared to other farms.
The results of this study indicate that the current use of formaldehyde foot baths on farms, disposal into manure pits, and manure spreading on fields, does not contribute to elevated levels of formaldehyde in air. Spreading manure that has been mixed with formaldehyde from foot baths is not expected to result in acute health effects.
In the summer of 2011, several Franklin county residents voiced concerns about the practice of using formaldehyde in cow foot baths. Foot baths are used to treat hairy heel wart (papillomatous digital dermatitis), a contagious disease that causes lameness in cows.
To make the foot bath, a 37% industrial solution of formaldehyde is diluted with water to a 2 to 5% solution, which is poured into walk-through foot baths and used to treat the cows’ hooves. The used bath solution is typically emptied into a manure pit. Manure is stored in the pit over the winter, or for shorter periods of time during the growing season. Manure is then spread on farm fields as a soil amendment.
Every year, the Agency of Agriculture implements a winter manure spreading ban under the Accepted Agricultural Practices (AAPs) from December 15 through April 1 to reduce nutrient run-off from frozen ground. In 2012, due to the early ground thaw and dry warm weather in March, the ban was lifted 10 days early, on March 21.
On March 16, 2012, Vermont’s Secretary of Agriculture and Commissioner of Health petitioned ATSDR to perform a study to determine if there is increased public exposure to formaldehyde associated with this agricultural practice. ATSDR granted the petition on March 30. A similar study had been planned for late 2011, but cold weather conditions made it impractical at that time.
- Letter to National Center for Environmental Health and Agency for Toxic Substances and Disease Registry
Two sites (farm houses and property) were selected to be tested for both outdoor and indoor levels of formaldehyde in the air. The sites are located in East Berkshire and Fairfax, Vermont. Both sites are near fields that will have manure spread from farms that are using formaldehyde foot baths.
Air samples were collected for testing before and during agitation of the manure pit, before manure was spread on the fields, while it was being spread, and after spreading. At each site, manure spreading was documented and testing was conducted daily, both inside and outside the home. Testing was conducted in May 2012.
Staff from the Vermont Agency of Agriculture and the Health Department collected samples and documented when manure was spread. ATSDR funded the sample testing. Samples were tested at an ATSDR contract laboratory.
ATSDR shared the testing data with state agencies, and these data are detailed in two studies:
- The ATSDR study describes the formaldehyde measurements in air at these two farms.
- The Department of Health study describes both the ATSDR data and additional data obtained by the Health Department and Agency of Agriculture, Food and Markets before and after the ATSDR study.
Earlier in 2012, in response to residents' concerns, the Agency of Agriculture funded and collaborated with the Health Department to conduct tests at farms that use formaldehyde in their foot baths. These tests were done to assess the farm environment as the formaldehyde solutions are mixed, used and then emptied into the manure pit.
Tests showed detectable levels of formaldehyde in the area of the farm where formaldehyde was being poured into containers, or inches above the foot bath while in use.
No levels of formaldehyde were detected in the milking parlors. No levels of formaldehyde were detected in the breathing zone of workers while milking when the foot baths were in use.
Formaldehyde comes from both natural and manufactured sources. It is everywhere in the environment, both indoors and outdoors. Rural areas are likely to have lower levels of formaldehyde in outdoor air than urban areas.
Major sources of formaldehyde in indoor air are pressed wood, carpeting, personal care products, and cigarette smoke. Auto emissions and other combustion processes are the major sources of formaldehyde in outdoor air.
Formaldehyde breaks down readily in the environment. In air, it is reported to degrade completely in about a day. In water and liquid waste, sewage or sludge, it will break down within a few days.
For more information about formaldehyde and health:
If you have questions
About this study:
Call the Health Department at 1-800-439-8550.
About formaldehyde use on farms:
Call the Agency of Agriculture, Food & Markets at 802-828-6531.