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July 10, 2012

Frustration and Mystery Surround Contaminated Compost

Leaf_curlIt was two weeks ago that Tom Moreau, the general manager of the Chittenden County Solid Waste District, noticed his tomato plants were curling and wilting. That compelled him to alert the public that soil and compost from CSWD's Green Mountain Compost might be toxic. He suspended sales and sent off samples for testing.

Now that lab tests have confirmed that both bulk and bagged soil and compost from GMC is laced with two persistent herbicides — clopyralid and picloram — the fallout is broad. As CSWD scrambles to do damage control, the state is trying to pinpoint where the de-listed substances came from. Gardeners, meanwhile, are salvaging what they can of their plants.

Both compounds kill broad-leaf weeds such as thistle and clover, though clopyralid was de-listed for use on lawns a decade ago. Picloram — which is sometimes used to manage grasslands, such as those on horse farms — requires certification for purchase and use. Yet the two compounds were found at levels between 1.7 and 15.3 parts per billion in some of the eight soil and compost samples that GMC had tested, which mystifies both GMC and state officials.

“Based on our records, there’s very little use of clopyralid, and picloram is restricted and not available to homeowners,” says Cary Giguere, section chief of the Pesticide Program at the Vermont Agency of Agriculture, Food and Markets. “We’re very confused as to why it’s shown up in lawn clippings. We're investigating illegal uses.”

GMC collects scraps and clippings solely from within Chittenden County, and how the herbicides ended up at their Williston facility is a puzzle. "I think what's most bothersome for us is the source," says Moreau. Though he suspects that clopyralid is being used at one local high school, picloram is essentially banned. "We thought, 'Oh my God, who is using picloram?'" A matrix of test results supplied by CSWD shows even higher levels of the two herbicides in a few samples of horse manure and grass clippings that the district also had tested.

Though picloram is available through online retailers, a special license is needed to purchase and apply it in all 50 states, and by law it must carry the word "Caution" on the label. Moreau says CSWD is working with the state to gather information on possible sources, and the state has already sent an inspector out to one local horse farm.

Though GMC tests each batch of compost for heavy metals and other pathogens before they're sold to the public, they didn't test for two compounds they thought were not in use. "You always beat yourself up with woulda, coulda, shoulda," says Moreau. "I've beat myself up plenty. But we're getting hit by something that's legally not supposed to be there."

Perhaps it's cold comfort that the substances were found in such trace amounts that the Vermont Department of Health says it is safe to eat produce from affected plants. “The models we use to assess the risk are very conservative,” says Sarah Vose, a toxicologist with the VDH. The levels of herbicides would need to be increased “thousandfold” to justify a health warning or to urge people not to eat the produce from their garden, she adds.

Still, it was enough to cause curling, wilting and cupping in plants for the hundreds of GMC customers who have gotten in touch so far. Since last year, GMC has sold roughly 24,000 bags of compost, 10,000 bags of potting soil, and nearly 5,000 bags of topsoil, as well as 3196 cubic yards of bulk compost. Any compost sold in bags this year was bagged at GMC's former Intervale location last summer, which means the herbicide use goes back to last season at least. Though not all of it is contaminated, its reach is far and wide.

In Winooski, Tim Riddle grows most of his own food each summer in a 1300-square-foot patch at his home. He hadn't used Green Mountain Compost for about eight years — he bought compost directly from farmers — but this year visited their new facility in Williston to check it out for himself. "I asked a ton of questions," he says, before he purchased one yard of compost at the end of May and spread it in his garden.

Very soon, he noticed leaf curl and "real slow growth" in some of his tomatoes and other broad-leaf plants. A gardener most of his life — the Riddles' garden won Organic Garden of the Year in 2005 from Gardener's Supply — he was confounded by the plant's distress, until he saw the press release from CSWD about two weeks ago. "For about five days, I couldn't even go into the garden," he says, adding that is wife was close to tears. "[The garden's] too much work and too much effort to essentially, literally be undermined at a root level."

Jason Wolstenholme of Burlington was also mystified by cupping on his tomato plants until news of contamination emerged. “I was battling my tomatoes curling. I only had a couple of blossoms, and everything else stayed shriveled,” says Wolstenholme, who adds that his peas looked “horrible.”

Wolstenholme says he purchased three yards of compost and four yards of topsoil from Gardeners’ Supply in May, which he spread on his organic home garden. After he found out about the soil’s possible toxicity, he pulled his tomatoes to find “really tiny root balls.”

Despite the health department’s green flag, Wolstenholme, a chiropractor, plans to remove all the vegetables in his garden and replace the soil. “It looks like one of the pesticides [picloram] is absorbed into the plant,” he says. “I’m not a big fan of toxic stuff.”

Wolstenholme says at the least, he would appreciate recompense for the compost they purchased.  “I would like to get my money back for delivery. If I bought a spoiled product, I would bring it back to the store,” says Wolstenholme, who has been doing his own research into compound half-lives to determine how long it might take for the herbicides to break down in his garden.

Moreau is also consulting with experts and colleagues nationwide to pinpoint how fast the herbicides might break down, so the company can pass on the most accurate information to customers. He has already noticed recovery in his own garden. “We’re trying to determine, what’s the longevity of this in the soil? That’s critical.”

So far, the soil contamination does not seem to have spread to commercial farms, which would have a higher bar to meet in terms of selling affected produce to the public. Giguere says he hasn't heard from any commercial growers yet. A call to the Intervale revealed that none of the growers there were affected. Mara Welton of Half Pint Farm says she avoids compost drawn from such a wide source as Chittenden County, which can be "unreliable for germination. The result is very inconsistent from a grower's perspective."

The compost has impacted at least one school garden, though. Smilie School in Bolton used a $7,300 grant designed to fight childhood obesity to build its first-ever garden. School officials, too, noticed plant wilt this spring. "We were just heartbroken," says principal Mary Woodruff, who says that most of the plants, including the new raspberry patch, will probably need to be pulled out and the soil replaced. "But then you just have to say, what are we going to do next? The plan is to get this [soil] out of there and get new soil in and salvage what we can."

Moreau says that GMC will begin doing bioassay tests, or growth trials in each batch of compost, before releasing it. For now, however, all sales are suspended, and CSWD is feverishly working out remediation strategies, trying to balance the relatively low level of contamination toxicity with damage to customer's gardens.

“We’re asking, what’s fair to people?” says Moreau. “Do we rebate the cost [of compost]? How do we compensate for plants? Then, we have to deal with our insurance company.” All options — including monetary compensation — are still on the table, according to Moreau, and the company has sent out another batch of samples for testing.

He adds that he feels victimized. "To put this in perspective, first and foremost, our customers bought a product that they thought was healthy for their soils, and it wasn't," he says. "We've invested $2.3 million in a public facility, and for a regulated product to make it into our soil....perhaps we're not as much as a victim as the poor homeowners and gardeners, but we're just frustrated." 

Though Moreau plans to eat the produce from his own garden this summer, the jury is still out for Riddle. "I'm assuming everyone's yields will be way down. We'll wait and see," he says. He usually produces hundreds of pounds of produce for consumption throughout the year. "This is supposed to be a relaxing time of year where garden's in, everything's great, and we soon start harvesting. We're hoping for the best. We need to eat."

Photo courtesy of Tim Riddle

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