Pesticide regulatory laws and policies around the world are well established, rigorous in many ways, and to a large extent, are harmonized. The methodologies and underlying data required to conduct pesticide risk assessments generally follow detailed and openly vetted international norms.
The outcomes of similar risk assessments sometimes vary from country to country, as is the case today in the evaluation of glyphosate carcinogenicity. But such differences arise more from variance in statutory or policy-driven evaluation criteria and burdens of proof, and/or acceptable risk thresholds, than from differences in the art and science of risk assessment.
Compared to pesticide regulation, the regulatory policy and infrastructure governing approval and review of GE crop impacts is in its infancy. The need for better science in support of the regulation of GE crop technology is made clear in a series of reports from 2002-2016 from the U.S. National Academy of Sciences (NAS).
Dozens of policy statements and reports from other scientific organizations and professional societies raise concern over the science base supporting GE crop technology regulation, and have called for basic science investments in GE-crop environmental and human risk-assessment methods, tools, and decision-making. Most such recommendations have not been acted upon.
The pesticide registration process defines and governs legal uses of pesticides in the US, while tolerances establish legal limits for pesticide residues in food and animal feed.
The end-point in the registration process isapproval of a legally binding pesticide product label, which gives rise to the often-repeated statement “the label is the law.”
Pesticide product labels specify the concentration of theor ingredients in , end-use products, as well as the concentration of other so-called “inert” ingredients in the product.
In most formulated pesticide products, as sold to farmers or applicators,make up one-third, to two thirds or more of the weight of the product.
The nation’s basic pesticide regulatory law – the Federal, Fungicide, and Rodenticide Act, or FIFRA –allows pesticide registrants to classify the identify and concentrations of inert ingredient(s) as “ ( ).”
FIFRA also allows registrants to shield CBI from disclosure via pesticide product labels, or in regulatory documents. For this reason, no one other than officials in the company owning a registration and the EPA knows the identity of the chemicals that account for one-third to two-thirds, and sometimes more, of the contents in a given pesticide product.
The failure to disclose herbicide product inert ingredients has become a major global issue, because of a series of published papers reporting that formulated glyphosate-based herbicides (GBHs) are 10-fold to 100-fold or more toxic to various organisms than 100% pure glyphosate.
This relatively new scientific insight raises significant concerns, since virtually all of the environmental, toxicology, and cancer tests conducted to date have been carried out using pure glyphosate, rather than formulated GBH products. Yet all users of GBHs, and the general public, never spray, nor are exposed to pure glyphosate alone.
Key Label Provisions
Pesticide product labels set forth how, and under what restrictions and conditions, a pesticide can be legally applied in the US. Pesticide labels are the predominant way that registrants and the EPA strive to avoid “unreasonable adverse effects on man or the environment.” Labels set forth maximum application rates, how many times a pesticide can be applied, and places and circumstances in which applications should be avoided, or are prohibited.
Labels also describe the safety precautions and protective equipment and clothing that individuals must wear when mixing, loading, and applying pesticides.
EPA efforts to curtail pesticide risks often play a supporting role in pesticide company efforts to shift market share from older products that are off-patent and marginally profitable, to newer, seemingly lower-risk proprietary products that generate greater profit per acre treated. The net impact of EPA actions taken to reduce risks is sometimes modest and short-lived.
The most consequential gap in EPA’s authority, and the way pesticides are regulated in the US and worldwide, is that regulators only focus on one pesticide at a time, without taking into account trends in overall pesticide use on a crop or set of crops, or in a given farming region.
There is no assessment, or weight placed upon how overall use, and the mix of pesticides accounting for the majority of use, might be impacting environmental and public health outcomes.
This is a major reason why public health professionals are concerned over recent intensification in overall herbicide use in the US, as well as the soybean production regions in Brazil and Argentina.
Strategies to Reduce Herbicide Risks
The EPA does have tools that could be used to make progress in reducing risks, if and when it becomes clear such action is warranted and politically viable.
EPA can alter the intensity of herbicide use in the Midwest in four primary ways.
The best options will impact several, if not all, herbicides in a similar way. Tackling the problem of rising herbicide use and risk one herbicide at a time is like “Whack-a-Mole.”
Achieving meaningful, net reductions in risk through actions impacting one herbicide at a time will take far too long and prove excessively expensive for both the EPA (taxpayers) and the industry, and farmers will grow weary of the perpetual, regulatory limbo.
Whenever possible and in the interest of fairness, the EPA should take similar actions on all herbicides associated with GE-HR. Impacted crops will include corn, soybeans, alfalfa, canola, and sugar beets. The top-priority herbicides would include glyphosate, glufosinate, 2,4-D, dicamba, and the “fop” family of ACCase inhibitors.
Key steps in the process could include:
1. Extend the pre-harvest intervals applicable to all herbicide labels governing post-emergence herbicide applications to GE-HR crops.
By increasing pre-harvest intervals (PHIs, the time between the last, legal application of a herbicide and the day the crop can be harvested), the EPA would reduce the time period during which herbicides could be applied, while also eliminating higher-risk, mid-summer applications.
Longer PHIs also reliably reduce residues in food at harvest, decreasing the quantity of herbicide active ingredient entering the food supply.
2. Limit when, how often, and at what rate GE-HR herbicides can be applied.
Herbicide labels set binding, maximum one-time application rates, and also set limits on the number of applications and/or the total volume of use on a given crop in a given year.
The EPA has recently approved significant label changes for several herbicides associated with GE-HR crops. These labels generally authorize much higher rates than typically the case in the past, more applications, and big increases in the maximum, season-long volume applied.
For example, historically over the last 30 years, 5% to 12% of national corn acres have been treated once with 2,4-D at a rate of about 0.4 pounds of active ingredient per acre. Farmers increased the average application rate to 0.57 pounds in 2014, as they intensified efforts to control glyphosate-resistant weeds.
The new Dow AgroSciences, Enlist Duo label for 2,4-D herbicides approved for use on GE-HR corn allows for three applications at a rate up to 1.0 pound per acre, for a maximum total of 3 pounds applied per acre per season – about seven-times more 2,4-D per acre than historic use patterns.
The industry will continue petitioning the EPA to approve herbicide labels that allow higher maximum rates, more applications per season, and higher limits on overall applications. Unless there is a change in policy, the EPA is likely to approve most such requests.
Instead, the EPA should develop and implement a policy that caps the increase in one-time application rates and the maximum, allowed number of applications, such that season-long use can increase no more than some fraction (say 50%) of historic, pre-GE crop rates and overall use.
3. Apply the additional 10-X safety factor mandated by the Food Quality Protection Act () when setting or reviewing the maximum allowable human exposure to herbicides associated with GE-HR crops.
To protect vulnerable segments of the population, and in particular pregnant women, their developing child, and infants and children, the FQPA calls for up to an added, 10-fold safety factor in setting what is called the “Population Adjusted Dose” (PAD) for pesticides.
This key regulatory parameter sets the volume of the “risk cup” that all uses of a given pesticide can fill, but should not exceed.
When the EPA lacks solid toxicological data to quantify pesticide risks to pregnant women, infants, and children, the FQPA mandates that the agency impose an added, 10-fold safety factor. This step, in effect, cuts the size of the allowable “risk cup” to one-tenth of its former volume.
In addition, the FQPA directs the EPA to impose up to a 10-X added safety factor when the agency lacks sufficient, current and credible exposure data to conduct high quality and refined human-health risk assessments.
Dramatic changes have occurred in herbicide uses and exposures through drinking water, food, and the air over the last decade, yet the EPA has not required, nor has access to credible, up-to-date dietary exposure data on any given herbicide, let alone exposures to all herbicides.
Only one crop in a single year has been tested for glyphosate residues by the U.S. Department of Agriculture – soybeans in 2009.
Because of uncertainty over contemporary herbicide use and exposure levels, the EPA should impose the full 10-X added safety factor on herbicides associated with GE-HR crops. Given that most herbicides rarely are detected in food at harvest, this reduction in the size of the allowable “risk cup” will likely not have a major or immediate impact, but for a few key herbicides, it likely will within the next five to 10 years.
One thing is clear from the dozens of petitions advanced by the pesticide-seed-biotech industry in recent years seeking higher tolerance levels – the way herbicides are applied on GE-HR crops can markedly, and even dramatically increase residues in food and animal feed, and such increases are bound to alter human exposure levels.
But because the EPA lacks solid data to estimate by how much, the agency is on solid grounds in imposing the added, FQPA safety factor.