BioCycle March 2010, Vol. 51, No. 3, p. 27
Presence of bifenthrin in some municipal green waste composts is threatening their certification for use in organic agriculture, and raising broader questions on limits for environmental contaminants detected in compost.
Dan Sullivan
BioCycle West Coast Conference 2010 Related Session:
Compost Utilization Trends, Opportunities
Tuesday, April 13, 2010
Presentation:
Municipal Compost Use In California Organic Agriculture

AS PART of routine inspection practices by organic regulators, live wheatgrass labeled “organic” was randomly pulled for testing from supermarket shelves in California in July 2009. The test turned up the synthetic pyrethroid pesticide bifenthrin. Following the July discovery and further testing, the California Department of Food and Agriculture (CDFA) – which oversees the National Organic Program (NOP) in California for the U.S. Department of Agriculture – sent letters to organic certifiers and some 3,000 organic farmers naming compost products that tested positive for bifenthrin. These included Nortech Gold, Grover Wonder Grow and Clean City Compost.
The first such letter, following consultation with the NOP, was sent to certifiers on August 5, 2009 concerning Nortech (a Nortech Waste LLC product). It stated in part: “Based upon a review of information obtained from the manufacturer and on-site sampling of suspected compost, laboratory test results have identified residues of bifenthrin and dichlorophenyl-dichloroethylene (DDE) in the compost. These chemical compounds are considered prohibited substances by NOP and are therefore prohibited for use in organic production.”
Subsequent letters were sent out Sept. 29, 2009 concerning Grover Wonder Grow (a Grover Landscaping product) and October 7, 2009 concerning Clean City Compost (a Recology product), telling certifiers that their clients could not use these products and that the contaminated compost should be disposed in a manner consistent with NOP requirements. The reason for this time lapse, according to one of the involved composters, was that the wheatgrass farmer kept switching product in order to remedy the problem, but each time the new compost tested positive for bifenthrin.
DDE is a breakdown product of the long-banned pesticide DDT. Bifenthrin is commonly found in commercial and residential pesticide products typically used to control ants such as Bifenthrine, Brigade, Capture, Ortho Home Defense Max and Scotts LawnPro Step 3.
“[DDE] is ubiquitous in the environment,” says Brenda Smyth, a division chief for CalRecycle, a new department within the California Natural Resources Agency that administers programs formerly managed by the state’s Integrated Waste Management Board and Division of Recycling. “Everybody knows it’s there, and there’s nothing anybody can do about it because of the historic uses of DDT.”
The major concern, she notes, is with the presence of bifenthrin because it’s still being produced and applied. While the U.S. EPA now considers bifenthrin relatively benign to humans and other mammals at levels it would most likely be encountered in the environment, it was at one time listed as a class C (suspected carcinogen) and Restricted-Use Pesticide (available for sale and use only to certified applicators or under their direct supervision). The Pesticide Action Network continues to include bifenthrin on its “Bad Actor Chemical” list as a possible carcinogen and suspected endocrine disruptor. What is not in dispute is its toxicity to fish; the California Department of Pesticide Regulations (DPR) is currently testing all synthetic pyrethroids, including bifenthrin, for their potential deleterious effects on aquatic species (juvenile species in particular).

A PERSISTENT PROBLEM
This isn’t the first time commonly used agricultural chemicals have turned up in compost. In 2000, the herbicide clopyralid began showing up in compost in the Northwest at levels of around .03ppm, hardly detectable but substantial enough to do damage to farmers’ and gardeners’ crops. A major difference with bifenthrin is that there is no indication it will either damage or be taken up by plants.
To obtain a broader perspective, CalRecycle gathered together a wide range of stakeholders for two roundtable discussions, one held at its Sacramento offices in October 2009 and another at the Ecological Farming (Ecofarm) Conference in January, 2010. Invited parties included representatives from CalRecycle, the NOP, California Certified Organic Farmers (CCOF), CDFA, DPR, commercial composters and consultants. Also invited were The Organic Center (TOC), an industry think tank, and the Organic Materials Review Institute (OMRI), a nonprofit that provides independent review and certification of products used in organic agriculture.
The difficult question at hand, noted Chuck Benbrook of TOC during an Ecofarm panel discussion entitled “Organic Farming in a Contaminated World,” is “what to do about low levels of contaminates that wind up in organic production through no fault of the organic farmer or even the organic input manufacturer, like a compost manufacturer … How do we not lose the benefits of compost in building healthy soil and sequestering carbon and producing healthy food – and in sustaining the economic viability of organic farms?”
Benbrook, who has made a career of studying pesticide toxicity, explained that “the risk of bifenthrin at the levels it’s in compost ever being in a harvested foodstuff is essentially zero – it could not happen. Anyone with any experience in pesticide risk assessment and dietary exposure would very readily agree with that. We don’t have a food safety risk here.”
“The reason that this is such a big issue is that most of us anticipate that if the compost supply in the U.S. was looked at in even a minimally systematic way, we would find a substantial portion of it contaminated with one or more pesticides … which leads to the question of are we really going to start testing compost and all of the other inputs to organic production for prohibited materials and holding the organic community to a standard of purity which is simply not attainable in the real world anymore?”

BIFENTHRIN IN COMPOST
The initial sample that tested positive for bithentrin and DDE included the crop mixed in with the growing media – in this case compost (the live wheatgrass was growing in trays in the store). These chemicals did not show up in subsequent testing of the crop only. “The wheatgrass was grown in 100 percent compost, and that’s an unusual practice,” says Matt Cotton of Integrated Waste Management Consulting. “They just happened to go to one product in the produce section that was grown in compost. It’s very unusual circumstances that’s brought us to where we are today.”
Cotton, who recently completed an assessment of California’s compost industry for CalRecycle, adds the state generates about four million cubic yards of compost annually; about 80 percent is from green waste feedstocks. He estimates that about two percent of that compost goes toward organic production. Recycling yard trimmings goes hand in glove with California’s stated goal of diverting at least 50 percent of organic materials away from landfills.
The NOP must decide what to do about the bifenthrin issue with regard to organic production and inform CDFA, which has the latitude to either follow that directive or petition the USDA for its own stricter standard. “We feel that bifenthrin and clopyralid are just the tip of the iceberg,” says Rachel Oster of Recology (formerly Norcal Waste Systems, Inc.), which operates composting facilities in California, Oregon and Nevada and sells OMRI-certified compost made from municipal yard trimmings to organic farmers and others.
“The compost industry would like to see the USDA Organic Program take a broad approach,” she adds. “We’re not adding anything to our product, and we’re trying to do the right thing by diverting these organic materials away from landfills and to their higher and better use. Pesticides are so prevalent and this type of situation is going to occur. I think the discussion shouldn’t be piecemeal – test, enforce, test, enforce – that isn’t going to be effective. They need to take a broader approach to the idea of synthetics in compost and establish broader criteria for that – otherwise they’re not addressing the broader problem.”

A FARMER’S DILEMMA
Zea Sonnabend, an organic inspector and materials specialist with CCOF and longtime coordinator for the Ecofarm conference, says the bifenthrin problem has been made even worse by the fact that farmers who use compost to boost fertility, improve soil structure and for its myriad other benefits have been shying away from manure-based compost in favor of compost made with yard trimmings ever since the E. coli outbreak linked to spinach in 2006. “Many of them are moving away from using compost altogether, and we’re trying to rectify that,” she says. “This problem with bifenthrin is really serious for them.”
California’s Leafy Greens Marketing Agreement (LGMA), a voluntary program signed onto by all major packing houses that ship lettuce and salad mixes across the U.S. and beyond, spells out specific Good Agricultural Practices (GAPs) that must be followed by their growers. This includes rigid requirements for farmers who use compost, such as testing for pathogens – specifically fecal coliforms, salmonella and E. coli 0157:H7 (the culprit in several deaths related to the 2006 spinach incident, although the source was not compost).
Other compost-handling parameters include minimum turning/covering and temperature requirements (a minimum of 131°F maintained for 15 days with a minimum of five turnings for windrow composters, and covering with at least 12 inches of insulating material while maintaining a minimum temperature of 131°F for aerated static pile composters). Farmers are required to either keep scrupulous records that they are following these requirements themselves or must obtain records from their compost supplier (and hold onto them for two years).
OMRI testing and certification covers many, but not all, of these rubrics, still giving growers who use compost a leg up on meeting the GAP standards. Even though bifenthrin is a nonissue where LGMA is concerned – except for organic growers who are part of the program – losing OMRI certification also mean composters who serve these farmers also lose this marketing advantage.
OMRI has already revoked its certification of Nortech Gold compost and continues to evaluate the other two products identified by CDFA. “We follow a different protocol than CDFA, allowing for due process and are treating them as complaints,” explains Lindsay Fernandez-Salvador, OMRI’s Technical Director. As of early March, OMRI had only removed the first of the three composters initially cited for bifenthrin contamination from its list of allowable products for organic production. “The other two are still under investigation at this time,” says Fernandez-Salvador.

NEXT STEPS
According to Section 205.203 of the NOP regulations: “The producer must manage plant and animal materials to maintain or improve soil organic matter content in a manner that does not contribute to contamination of crops, soil or water by plant nutrients, pathogenic organisms, heavy metals, or residues of prohibited substances.” This section of the statute goes on to state: “The producer may not use any fertilizer or composted plant and animal material that contains a synthetic substance not included on the National List of synthetic substances allowed for use in organic crop production.”
Miles McEvoy, Deputy Administrator of NOP and a speaker/participant in the CalRecycle roundtables, has suggested that the language may not apply to bifenthrin and other prohibited materials that find their way into compost through no fault or intention of the composter. One near-term solution on the table would be to allow for the presence of these materials in compost based on EPA maximum allowable levels for pesticide residues on conventional food crops. The NOP regulations already specify that for organic food crops, this shall not exceed five percent of what’s tolerated for conventional crops.
EPA pesticide-residue tolerance levels for bifenthrin range from 4.5 ppm for cabbage to .05 ppm for peanuts. An NOP draft proposal put bifenthrin in a category of Unavoidable Residual Environmental Contaminants (URECS) specifically addressed in the NOP regulations and suggested a lowest allowable limit for compost of .05 ppm (if following the protocol for organic food, this could have been set as low as .0025 ppm).
Despite the apparent compromise, organic certifiers say such a protocol would be devastating. “The first thing we did is get back to the NOP with formal feedback on their proposed policy, and we said ‘let’s go get some data,'” said Jake Lewin, CCOF’s Chief Certification officer during the January Ecofarm panel discussion. “We went to farms using compost made with municipal yard waste. We took three samples. Two came up with bifenthrin in amounts of .09 ppm and .07 ppm, and another one with residues undetectable.” Lewin elaborated that the third sample tested had been made up of about one-third purchased compost mixed in with animal manure and farm residues.
“What we basically believe from that first test is this proposed policy would just legislate these materials out of existence,” he commented. “… It would make it impossible to have these materials in use because .07 ppm would be beyond the tolerance and the material would be out. That’s a problem.”
Following Lewin’s voiced concerns, McEvoy said there might be a better way. “We’re looking at changing the approach here and instead of requiring testing of municipal yard waste compost, requiring testing of the crops that come off the field where the municipal waste compost is used.”

MORE DATA
What’s clearly needed, says Smyth of CalRecycle, is more data. But gathering such data is made difficult by the uncertainties surrounding NOP’s, CDFA’s and OMRI’s next moves, with composters wary about getting involved – or even of looking too closely at their own products – for fear of being singled out. “What we have now is kind of a ‘don’t ask, don’t tell’ situation. … CalRecycle feels it needs to understand what’s going on and would like to have more data,” says Smyth. “But we can’t get the data without a time out where we won’t have [composters paying] punitive damage for increased knowledge.”
Smyth said a letter from NOP formally stating some of the salient points of the roundtable discussions would be helpful – specifically that the USDA Organic Program will indeed view environmental contaminants that show up in compost, such as bifenthrin, as URECS rather than disallowed synthetic substances, and that the agency is moving toward a strategy to test the final food product rather than the compost or the soil.
“We’re working on a letter and we hope to have it out before the National Organic Standards Board meeting at the end of April,” NOP Deputy administrator McEvoy confirmed to BioCycle. That meeting, scheduled for April 25-29, 2010 in Davis, California, is also when the NOP intends to make its next steps known. “What we’re working with is a way for growers who use municipal green waste compost to test crops to determine whether there’s any residual pesticides on the crops. We’re trying to figure out what the parameters are. Is it every field? Is it every crop? In theory it sounds great, but there are a lot of questions.”
In answering those questions, adds McEvoy – who headed up Washington state’s pioneering organic program for nearly two decades before joining the USDA this year – the policy put in place will have to balance identifying real environmental risks with not being so burdensome as to create a de-facto ban on municipal green waste composts. McEvoy also points to the need for more data, offering that current research by the Agricultural Marketing Service showed promise of offering just that. But as far as a “time out” to allow California officials an amnesty period to collect data from composters, he said that’s not in the cards.
“That’s what they had requested, but we’re not going to provide that,” he says. “We’re not going to say ‘these products can be allowed’ without having anything else in place. We’re going to put something else in place that’s different from what we have now. We have to recognize we don’t live in a pristine environment. At the same time, we have to be aware what contaminants are out there and eliminate them from the organic system as best we can, because that’s what consumers expect.”

Dan Sullivan is an environmental journalist specializing in food and agricultural issues.
Sidebar p. 30
DOES SUNLIGHT BREAK DOWN BIFENTHRIN?
A 2006 STUDY published in the Journal of Agricultural and Food Chemistry seems to corroborate what some California composters are saying anecdotally: The persistent pesticide bifenthrin breaks down upon exposure to sunlight. The article, entitled “Enantioselective Degradation and Chiral Stability of Pyrethroids in Soil and Sediment,” listed bifenthrin as one of a handful of synthetic pyrethroids susceptible to photodegradation and suggests that breakdown might be enhanced by bolstered microbial life.
One California composter whose product was prohibited for use in organic production by the California Department of Food and Agriculture this past summer due to the presence of bifenthrin reported moderate success with exposing yard trimmings feedstock to sunlight before mixing it into the compost pile. The composter, who asked not to be identified, said that while initial results showed promise, the levels didn’t come down enough. He added that increased microbial activity would likely have led to greater success.
While the research offers some promise, the suggested remedy – exposing as much of the compost pile to surface sunlight as possible via, for example, a frequently turned windrow – flies in the face of other emerging compost technologies aimed at reducing emission of volatile organic compounds (VOCs). “It’s very difficult when you have aerated static pile technology and not composting in open windrows,” says Rachel Oster of Recology, where a newly installed composting system at the company’s Jepson Prairie Organics site outside Vacaville, California, shows promise of reducing VOCs by as much as 90 percent. “We’re covering because of the VOC issue and we’re trying to get those down, while meanwhile you are not seeing the sunlight [exposure] like you are in a windrow.”