The Chittenden Solid Waste District released a statement on Friday evening alleging that the trace amounts of herbicide in its Green Mountain Compost this spring has also been found in six compost products from five local companies.
The district has sent 84 samples of material from its own compost handling facility, including grass clippings, horse manure, leaves — in addition to commonly used feed for horses and compost from Vermont companies.
The district had seven other local compost products tested as part of an effort to figure out why its compost caused plants to die-off this summer. Horse manure from 12 stables that send material to the district also tested positive for trace levels of herbicides.
The Vermont Department of Health has said that trace levels of the herbicides, picloram and clopyralid, are not dangerous to human health.
Tom Moreau, general manager of the Chittenden Solid Waste District, said in a statement: “All 12 samples of individual horse farm manure and bedding show the presence of one or both of the persistent herbicides,” Moreau said. “Given that trend, we sampled some horse feed used by the farmers and four of the national brand of bagged products have tested positive for one of the herbicides.”
Samples of bagged horse feed from Purina, such as Equine Senior, Ultium and Strategy, tested for between 104 ppb and 465 ppb of clopyralid, a commonly used herbicide manufactured by Dow AgroSciences.
The concentration levels found in compost from Vermont Compost Company, Foster Brothers products (including MooDoo), Grow Compost and Champlain Valley Compost are less than those discovered in Green Mountain Compost, according to data from the district.
Green Mountain Compost has had concentrations of less than 16 parts per billion of picloram, another herbicide, and clopyralid. Other local compost companies have tested for trace amounts of one or the other of the persistent herbicides, ranging from 2.8 ppb to 13.3 ppb.
Steve Wisbaum, who owns Champlain Compost, says the results from Chittenden Solid Waste District are “questionable.” The district didn’t ask permission to test his compost which he said is sold retail via bulk delivery. The test results the district reported came from a customer claim and could not be verified, he said. He has received no reports of damage to plants.
None of the other local products have reported plant die-off or plant deformities like those caused by Green Mountain Compost.
Attempts to reach owners of compost companies and stable owners on Sunday were unsuccessful.
Moreau said he discovered the problem on June 25, when his own tomato plants failed to thrive. The district sent out samples to Anatek Laboratory in Spokane, Wash., which is widely used by scientists for chemical testing.
On July 25, the district began canvasing gardeners in the region, seeking out consumers who had problems with the compost. So far, 507 residents have filed claims for refunds at a total cost of nearly $1 million to the district. About 70 percent of the claims from 420 gardeners have been verified, according to the district. Field technicians from UVM are helping to confirm the claims.
Moreau estimates the district will spend $1.4 million on the rebates, testing and lost product sales.
The district is working with the University of Vermont College of Agriculture and the Vermont Agency of Agriculture, Food and Markets to determine the cause of the problem and mitigate damage to plants.
The Vermont Agency of Agriculture, which regulates pesticides and herbicides, is conducting an investigation into the source of the picloram and clopyralid found in Green Mountain Compost, according to a statement from Chuck Ross, secretary of the agency.
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“The focus of our investigation is to determine if these products were used in a manner that complies with state and federal regulations,” Ross said. “If misuse is detected within the state, we will take appropriate regulatory action. Once the investigation is complete, we will have information to provide guidance to growers and compost producers.”
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Ross says the herbicide residues could be from material imported from outside the state. “If that is the case, we will attempt to trace that matter back to its point of origin and bring the issue to the attention of the Environmental Protection Agency (EPA),” Ross said. Under the Federal Insecticide Fungicide Rodenticide Act, state agencies may report adverse impacts from pesticides to EPA.
Ross said his agency will not provide the public with any more information until after the probe has been completed.
Editor’s note: This story was updated at 1:51 p.m. with information from Steve Weisbaum.