Pesticide Residues in Organic Food — Delivering on a Promise
June 3, 2014
Avoiding pesticide exposure and risks remains the #1 reason most people choose organic food. This is not likely to change until there is convincing data that show only modest differences between the pesticide dietary risks associated with residues in and on organic food, compared to conventionally grown food.
Pesticide risk is a function of four interactive variables: the inherent toxicity of a specific pesticide, the level at which it is present in a given food, how much of the food is consumed in a typical day, and the timing of the exposure in terms of a person’s life history. Fortunately, much is known now about the frequency and levels of pesticides in commonly consumed foods (conventional and organic), as well as pesticide toxicity. In addition, ongoing research continues to discover and unravel factors that increase the risk stemming from a given pesticide exposure episode, like pregnancy, a compromised immune system, or certain genetic polymorphisms.
Using risk assessment methods based on Environmental Protection Agency (EPA) science policies and data on pesticide toxicity, the Measure to Manage (M2M) program has built and applied a pesticide Dietary Risk Index (DRI) system to residues in conventionally grown and organic foods, and also domestically grown versus imported foods.
With my colleague Brian Baker, I have published an open-access paper in the journal Sustainability analyzing the pesticide residues found in organic foods by the U.S. Department of Agriculture’s highly regarded Pesticide Data Program (PDP).
Our Sustainability paper provides an overview of all residues found in organic food in the last decade. We used four categories to characterize all residues found in organic food: legacy contaminants like the long-banned organochlorine insecticides, fungicides used post-harvest in packing sheds, pesticides approved for use on certified organic farms, and “other” pesticide residues.
In domestically-grown organic food from 2002-2011, post-harvest fungicides and legacy chemicals accounted for just under 50% of the total 905 residue detected. Organic farmers have little control over either of these sources of residues. Another 197 residues were found of pesticides allowed for use on organic farms – mostly the bioinsecticide spinosad. “Other” residues accounted for 29.2% (265) of the total number of residues detected (905).
The core of our paper assesses the impact of current National Organic Program (NOP) policies and requirements that target pesticide residues in organic food. We address the degree to which the NOP, organic rules, and certifiers are helping to avoid pesticide residues that pose even modest levels of risk.
Current NOP policy allows food to be sold as organic as long as it contains residues of a prohibited pesticide that are below 5% of the applicable EPA tolerance. We assessed the degree to which this policy targets relatively high-risk residues, and concluded it does not.
We also introduced a new concept that we feel will help the NOP and certifiers better target efforts to continuously drive down pesticide risks in organic food. We define “Inadvertent” residues in organic food as those over which the organic farmer has little or no control — residues in soil or irrigation water, residues that drift onto an organic field from a nearby conventional farm, or residues that find their way onto organic food during packing, storage, or shipment (like post-harvest fungicides).
We found that the vast majority of “inadvertent” residues are present at levels far below those found in conventional foods – 10-times to 1,000-times lower. We show that the vast majority poses very modest risk, and hence should not be the primary target of NOP and certifier enforcement actions focused on reducing pesticide risks.
Our analysis leads to three encouraging conclusions –
- Consumers hoping to reduce pesticide dietary exposures and risk through seeking out organic fruits and vegetables are accomplishing this objective;
- The majority of residues found in organic food are low, or very-low risk inadvertent residues over which the farmer has little control; and
- Data and tools now exist for the organic community to systematically target and avoid possibly risky pesticide residues in organic food, although some changes in NOP policy and requirements will be needed to fully exploit new knowledge in the effort to drive down pesticide risks.
Our paper is one of 12 in a special issue of the journal Sustainability focused on organic food and farming. All the papers are free to download (i.e., “Open Access”). WSU graduate Jennifer Reeves, now at Utah State University, served as the Guest Editor for this special issue. Here are the abstracts of all 12 papers.