By James V. Aidala, Lisa R. Burchi, and Barbara A. Christianson

On February 25, 2022, the U.S. Environmental Protection Agency (EPA) announced it has issued a response denying the objections filed against its final rule revoking all chlorpyrifos tolerances (Response). EPA issued the August 18, 2021, final rule in response to the Ninth Circuit Court’s Order directing EPA to issue a final rule in response to Pesticide Action Network North America and Natural Resources Defense Council’s 2007 petition, which requested EPA to revoke all chlorpyrifos tolerances.

After issuing the August 2021 final rule, and consistent with the Federal Food, Drug, and Cosmetic Act (FFDCA), EPA provided an opportunity for any interested party to file an objection to any aspect of the final rule and request a hearing on those objections. Several objections were filed, with concerns ranging from the scope of the revocation of tolerances, the economic and environmental impacts of the revocation, and the implementation timeframe. EPA stated that after careful consideration, it denied all objections, hearing requests, and requests to stay the final rule filed during the period for submitting responses to the final rule.

In addition to its Response, EPA issued letters to the registrants of chlorpyrifos products with food uses confirming revocation of the tolerances and providing options for cancellation and label amendments. In particular, these options include the ability for registrants to submit registration amendments to remove food uses from product labels or submit a voluntary cancellation for products where all uses are subject to the tolerance revocation. For registrations not voluntarily cancelled, EPA stated it intends to issue a Notice of Intent to Cancel under the Federal Insecticide, Fungicide, and Rodenticide Act to cancel registered food uses of chlorpyrifos associated with the revoked tolerances. A copy of its Response and the accompanying order in the chlorpyrifos final rule docket is available at EPA-HQ-OPP-2021-0523.

EPA states that this action will be incorporated into the ongoing registration review of chlorpyrifos and it will continue to review the comments submitted on the chlorpyrifos Proposed Interim Decision, draft Revised Human Health Risk Assessment, and draft Ecological Risk Assessment. These documents are available in the chlorpyrifos registration review docket at EPA-HQ-OPP-2008-0850. After considering public comments, EPA will proceed with registration review for the remaining non-food uses.

Additional information on chlorpyrifos is available on our blog and on EPA’s website.

Commentary

It is not surprising that EPA denied all objections to its tolerance revocation decision. Since the earlier decision in 2009 to revoke the tolerances for the insecticide carbofuran, EPA, along with advocates of greater restrictions on pesticide exposures, have found a pathway for terminating pesticide uses while avoiding the significant procedural requirements of FIFRA’s cancellation provisions. The elaborate legal niceties of either approach will likely not quiet those grower groups and others who challenged EPA’s decision in this case.

Of note, in its lengthy Response (51 pages in the Federal Register, 87 Fed. Reg. 11222 (Feb. 28, 2022)), EPA again admits that some uses of chlorpyrifos on certain crops in certain areas are “high benefit” uses that can meet the required safety standards even when using EPA’s most conservative assumptions. Those eleven crop uses were among the many additional uses of the insecticide, and here EPA is explaining its case that as part of its decision, all of the uses on the current label are to be assessed together. At the point in time when EPA most recently assessed chlorpyrifos uses (the 2020 registration review Pesticide Interim Decision), some uses may have been able to meet the standard, but as explained in this notice: “In the final rule, EPA assessed aggregate exposure based on all currently registered uses of chlorpyrifos as required by the FFDCA and consistent with its guidance.”

This will likely be of little satisfaction to growers who produce those crops identified by EPA as meeting the standard.

To affected growers, the revocation of tolerances for the identified crop uses that nonetheless could meet the standard, along with the long-winded denial of objections citing the fine points of the legal procedures, amount -- to them -- as what Justice Scalia once described as “pure applesauce.” (Ironically, according to EPA’s 2020 assessment, applesauce sourced from New York and Michigan apples would have met the required standards according to EPA’s 2020 risk assessment.) Those groups may decide to continue the legal back-and-forth process for further review of the original decision and now the objection denials.

But the larger question for all registrants and pesticide users, not just chlorpyrifos, is what longer term issues are raised by EPA’s approach.

• Email This
• Print
• Comments

By James V. Aidala

In early July 1996, I was returning on a flight from Amman, Jordan, wondering what kind of negotiation we in the Clinton Administration faced in completing the legislative text of what became the Food Quality Protection Act (FQPA). (I had been asked to go to Jordan to visit the Jordanian pesticide regulatory program by a friend who was a senior official at the State Department. The result of my visit may have played a very, very small role in the Middle East peace process -- but that is another story for another time).

Some weeks earlier, I had been approached by Congressional staff members whom I knew from my previous job at the Congressional Research Service (CRS) as the subject area expert on the Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA) and pesticide regulation. I joined the Clinton Administration as a political deputy in the U.S. Environmental Protection Agency’s (EPA) Office of Prevention, Pesticides, and Toxic Substances (OPPTS, now renamed as the Office of Chemical Safety and Pollution Prevention (OCSPP)). Dr. Lynn Goldman was the Assistant Administrator who had recruited me to join the efforts to reform, that is, modernize, the Delaney Clause of the Federal Food, Drug, and Cosmetic Act (FFDCA). Over the years since it was enacted in 1958, risk assessment methods and our understanding of possible cancer risks had changed greatly.

Setting the Context

In 1989, the National Academy of Sciences issued a report on “The Delaney Paradox,” examining how the Delaney Clause ironically prevented safer new pesticides from entering the market. After an important court decision (Les v. Riley), EPA was told that even if it was undesirable public policy, the law can only be changed by Congress. As EPA went along with its work, many feared that numerous pesticides might be forced off the market even if, using modern evaluation policies, they presented little risk or were in fact safer than the alternatives.

During this time, advocacy groups were concerned that the then-current law was not protective enough of the possible risks to children’s diets. A simple way to say this is, for purposes of risk assessment: “Children are not little adults,” and supporters emphasized that dietary risk assessments by EPA should pay special attention to possible children’s risk given differences in metabolism, growth stages, and other important physiological characteristics.

This led to another National Academy of Sciences report in 1994 on “Pesticides in the Diets of Infants and Children,” which recommended that pesticide regulation include particular attention and possibly greater regulation of estimated dietary risks from pesticides. Given that the new Assistant Administrator of OPPTS was Dr. Lynn Goldman, a pediatrician, this concern was a priority for the Clinton Administration.

“The Gingrich Revolution”

A less noticed irony, but also important to the history of FQPA, is the change in party control of the House of Representatives, led by Representative Newt Gingrich (R-GA) and the “Contract with America” during the 1994 elections. Unexpectedly, the Republicans had the majority in the House for the first time in 40 years, and they elected Representative Gingrich Speaker of the House.

Much longer stories have been and will be written, but shortly after taking power in the House in January 1995, the Republicans were viewed as letting lobbyists run amok -- even suggesting amendments to environmental laws while lobbyists were sitting on the dais of Committee meetings. By the end of 1995 and going into an election year in 1996, “word was” the leadership, at least on the House Energy and Commerce Committee -- chaired by Representative Thomas Bliley (R-VA) -- was looking for a “green vote” to offset the image of an anti-environment House majority. Led by staff from the office of Chair Bliley and Representative John Dingell (D-MI), who was the senior Democrat on the Committee, a draft of a compromise bill was floated and made its way to my office at EPA.

Meantime, during the previous Congress (103rd Congress, 1993 - 1994), a team of EPA staff, led by Jim Jones (a later even more famous name in EPA pesticide regulation) of the Assistant Administrator’s office, along with staff from the Office of Pesticide Programs (OPP) and the Office of General Counsel (OGC), and staff from the U.S. Department of Agriculture (USDA) and the U.S. Food and Drug Administration (FDA) (it takes a village), had developed a Clinton Administration bill that did not gather much support during 1994. The legislation did have the core concepts of “fixing Delaney” and including the “reasonable certainty of no harm” standard, and it incorporated strong protections about possible risks from residues in the diets of infants and children.

In the new Congress (the 104th), there was some action during 1995 in the House Agriculture Committee on FIFRA issues related to antimicrobial products, minor uses of pesticides, and ways to prod the registration process to become more predictable and timely (this was before the Pesticide Registration Improvement Act (PRIA)). The FIFRA amendments were not viewed as controversial and were successfully discussed between both sides of the aisle (the Agriculture Committees were much more bipartisan in those days). By itself, that package was not likely to make it through the legislative gauntlet, given the shift in political power on the Hill.

Also in 1995, Carol Browner (the EPA Administrator) cautioned us that successful bipartisan legislation was unlikely, so not much effort should be invested, given other priorities.

The key event came in the late spring of 1996, when we first saw a draft of the legislation floated by the staff of Representatives Bliley and Dingell. It was far from perfect, but it included the core elements of what the Administration had proposed in the previous Congress. Since that earlier bill had been drafted with the coordination of EPA, FDA, and USDA, if it had the essential ingredients, we thought it might be a viable vehicle for further discussion. We also sought comment from some of the influential environmental groups that had been disappointed in the Administration’s legislation in the previous Congress. Suffice it to say, inclusion of the core elements of a tough standard (reasonable certainty of no harm) and special protections regarding children’s diets made the proposals a “possible” vehicle for further discussion.

We also started to have discussions with the staff of Representative Waxman (D-CA) in the House and Senator Kennedy (D-MA). Representative Waxman was the ranking Democrat on the Energy and Commerce Subcommittee, and Senator Kennedy was the ranking Democrat on the Labor Committee, which had jurisdiction over the FFDCA.

Back to July 1996

To shorten the story, we had intense, long meetings with the various interested parties -- pesticide registrants; environmental groups; trade associations; agency staff at EPA, FDA, and USDA; Congressional staff from the authorizing Committees; and Administration leaders within the agencies and the White House. In an amazingly short time, we came to agreement over the text, which is now FQPA. Representatives Waxman and Roberts (R-KS -- Chair of the House Agriculture Committee) held a press event about the historic compromise -- even more historic since the two Representatives rarely agreed on significant legislation. Their joint endorsement and statement of support signaled to members of both parties on both sides of Capitol Hill that this was an unusual, and important, compromise. The Congressional staff then recognized the next hurdle: the August recess was approaching fast, and if not enacted into law by then, the delay could be fatal, or at least make matters more complicated, as the multitude of interest groups would likely pick apart and want further changes to the agreement that had been reached. So the rush was on to get the “green vote” to the floor of the House and Senate.

Some last-moment hiccups took a little more time. Senator Lugar (R-IN), the Senate Agriculture Committee Chair, wanted a hearing to at least review the legislation. This was not a huge hurdle, but finding time on the floor was a race against the clock before the August recess. The House was the first to vote on July 23, 1996. The bill was approved with a surprising unanimous roll call vote in the majority Republican House (the vote was 417-0 with 16 not voting). Unanimous bipartisan support! -- imagine that in today’s world.

Then, with a sprinkling of clarifying (that is, reassuring) pieces of correspondence, the Senate agreed to the House legislation under unanimous consent. (In fact, for any trivia nuts out there, if you watch the C-SPAN video of how long the Senate deliberation lasted at the end of the day on July 24, 1996 -- the request for unanimous consent and agreement clocks in under 30 seconds.)

So with unanimous support in both the House and the Senate, FQPA was approved.

One Last Step

One very important last step was needed before FQPA became law -- the President needed to sign the legislation. That happened at the White House when H.R. 1627 was signed by President Clinton on August 3, 1996.

• Email This
• Print
• Comments

By James V. Aidala, Lisa R. Burchi, and Barbara A. Christianson

On August 18, 2021, the U.S. Environmental Protection Agency (EPA) announced that it will stop the use of the pesticide chlorpyrifos on all food. In the pre-publication of the Federal Register notice released on August 19, 2021, EPA revoked all “tolerances” for chlorpyrifos, which establish an amount of a pesticide that is allowed on food. In addition, EPA states that it will issue a Notice of Intent to Cancel under the Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA) to cancel registered food uses of chlorpyrifos associated with the revoked tolerances. EPA has stated the cancellation order will follow in approximately six months after the tolerance revocations.

EPA’s announcement responds to the Ninth Circuit’s order, issued on April 29, 2021, that vacated EPA orders issued in 2017 and 2019 denying a 2007 petition filed by Pesticide Action Network North America and Natural Resources Defense Council. That petition requested that EPA revoke all chlorpyrifos tolerances, or the maximum allowed residue levels in food, because those tolerances were not safe, in part due to the potential for neurodevelopmental effects in children. The 2017 and 2019 orders denying the 2007 petition were challenged in the Ninth Circuit by a coalition of farmworker, health, environmental, and other groups.

In its order, the Ninth Circuit found that “...EPA had abdicated its statutory duty under the Federal Food, Drug and Cosmetic Act (FFDCA) ...” to “conclude, to the statutorily required standard of reasonable certainty, that the present tolerances caused no harm.” After vacating the 2017 and 2019 orders, the court remanded the matter to EPA with instructions to: “(1) grant the 2007 Petition; (2) issue a final regulation within 60 days following issuance of the mandate that either (a) revokes all chlorpyrifos tolerances or (b) modifies chlorpyrifos tolerances and simultaneously certifies that, with the tolerances so modified, the EPA ‘has determined that there is a reasonable certainty that no harm will result from aggregate exposure to the pesticide chemical residue, including all anticipated dietary exposures and all other exposures for which there is reliable information,’ including for ‘infants and children’; and (3) modify or cancel related FIFRA registrations for food use in a timely fashion consistent with the requirements of 21 U.S.C. § 346a(a)(1).”

In its announcement, EPA states that it has determined that the current aggregate exposures from the use of chlorpyrifos do not meet the legally required safety standard that there is a reasonable certainty that no harm will result from such exposures. Chlorpyrifos is an organophosphate insecticide used for a large variety of agricultural uses and has been continually reviewed with regard to potential adverse effects, including possible neurological effects in children, which has been the subject of considerable controversy for many years. EPA’s announcement notes that a number of other countries, including the European Union and Canada, and some states, including California, Hawaii, New York, Maryland, and Oregon, have taken similar action to restrict the use of this pesticide on food.

EPA states its action also will be incorporated into the ongoing registration review for chlorpyrifos. EPA is continuing to review the comments submitted on the chlorpyrifos proposed interim decision, draft revised human health risk assessment, and draft ecological risk assessment. These documents are available in the chlorpyrifos registration review docket EPA-HQ-OPP-2008-0850 at www.regulations.gov and a discussion of these issues is available on our blog here.

After considering public comments, EPA will proceed with its registration review of the remaining non-food uses of chlorpyrifos by issuing the interim decision, which may consider additional measures to reduce human health and ecological risks.

Commentary

Separate from any issues of science, evidence, or interpretation, the FFDCA’s channels of trade provision is designed to address what happens if EPA cancels a pesticide product for not meeting Food Quality Protection Act (FQPA) standards and then revokes the tolerance. EPA’s initial description of its decision was unclear on this important point regarding the status of food already in the channels of trade that may contain chlorpyrifos residues.

EPA statements at an August 18, 2021, phone briefing with agricultural stakeholders appeared to present a position that the tolerance revocations would be in effect immediately upon publication in the Federal Register. This implied that there may be an immediate revocation of the tolerances before any parallel action to cancel the associated pesticide registrations. The pre-publication version of the notice clarified that the revocation of chlorpyrifos tolerances would not become effective until six months after the publication of the notice in the Federal Register.  As of August 24, 2021, the notice has not been published in the Federal Register.

This revocation delay of six months aligns with the statement also made by EPA to cancel the registration of chlorpyrifos food use products six months after the revocation notice. EPA may face questions from some of the groups that have been advocating for this type of EPA action concerning why, if these tolerances need to be revoked, the use of the pesticide will continue in effect for the remainder of this growing season. Ed Messina, Office Director of the Office of Pesticide Programs, made a glancing reference to this at the phone conference when he stated EPA and the U.S. Food and Drug Administration (FDA) are “having discussions.” 

According to EPA, use of chlorpyrifos has been in decline due to restrictions at the state level and reduced production. EPA also notes that some alternatives have been registered in recent years for most crops, other chemistries and insect growth regulators are available for certain target pests, and that EPA is committed to reviewing replacements for and alternatives to chlorpyrifos. Some growers, however, are using registered chlorpyrifos products on food crops and hoped to be able to continue certain uses. 

EPA states in the pre-publication notice that some uses in certain areas appear to be able to meet the FQPA standard as evaluated in its 2016 and 2020 risk assessment documents, even if including the full 10x FQPA “extra” safety factor (these assessments are the reference documents EPA cites in its revocation notice). EPA further states that the Ninth Circuit’s order did not provide EPA with time to consider further changes to the use patterns or label restrictions to align with such changes hinted at in the revocation notice, and so EPA is issuing the revocation decision now. This begs the question of whether EPA might consider some continued uses in the future, although even considering any “new” tolerance would be very controversial.

In addition, none of the current actions affect (for now) the tolerances for stored grains using the sister chemical (chlorpyrifos-methyl) with a similar toxicological profile. There also are non-food use applications of chlorpyrifos, for example, mosquito control application of chlorpyrifos sprayed over a large area, that are not affected by the tolerance revocation.

This mix of messages may not be easy to explain to users and the consuming public. 

Issues regarding the timing of the revocations and continued uses are also likely to present challenges for FDA. For example, there are various blended commodities (e.g., animal feed grain, possibly co-mingling harvests from different times) where FDA may be unable to determine what part of any enforcement sample came from a particular date of use.

The orderly transition for treated commodities was designed to avoid public and grower confusion that characterized the episodes of StarLink corn chaos in 2000 or the Cheerios contamination incident in 1994 involving a reported over 100 million boxes of cereal that were eventually destroyed. EPA cites international trade obligations as another reason for the coordinated actions effective in six months to notify foreign trading partners with a “reasonable interval” for adjusting to a changed regulatory situation.

Additional information on chlorpyrifos is available on our blog.

• Email This
• Print
• Comments

By Lisa M. Campbell, Lisa R. Burchi, and James V. Aidala

On December 7, 2020, the U.S. Environmental Protection Agency (EPA) issued for comment the Proposed Interim Decision (PID) for chlorpyrifos.  85 Fed. Reg. 78849.  EPA announced it is proposing new risk mitigation measures to address potential human and environmental risks identified in EPA’s September 2020 draft risk assessments.  The PID proposes the following measures:

• Label amendments limiting application to address potential drinking water risks of concern.
• Additional personal protection equipment and application restrictions to address potential occupational handler risks of concern.
• Spray drift mitigation, in combination with the use limitations and application restrictions identified to address drinking water and occupational risks, to reduce exposure to non-target organisms.

EPA states that the PID presents proposed mitigation with the 10-fold (10x) Food Quality Protection Act (FQPA) safety factor, reflecting the uncertainties around doses that may cause pre- and post-natal neurodevelopmental effects.  Under FQPA, EPA evaluates new and existing pesticides to ensure they can be used with a reasonable certainty of no harm to infants, children, and adults.  EPA is required to consider the special susceptibility of children to pesticides by using an additional 10x safety factor unless adequate data are available to support a different factor.  EPA additionally included a FQPA factor of 1x to reflect the range of potential risk estimates of chlorpyrifos, as illustrated in the September 2020 draft risk assessments.

Comments on both the September 2020 draft risk assessments and the PID are due on or before February 5, 2021.  EPA states that by holding the comment period for both actions at the same time, the public has access to more information and can provide more informed, robust comments.  Comments can be submitted at EPA-HQ-OPP-2008-0850.

EPA announced that it will also consider the input and recommendations from the September 2020 Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA) Scientific Advisory Panel (SAP) meeting once it releases its report in December 2020.  Depending on the SAP’s conclusions, EPA may further revise the human health risk assessment. 

Commentary

The inclusion of both 1x and 10x calculations for the appropriate FQPA safety factor is unusual.  EPA states the final decision on the appropriate FQPA safety factor is partly dependent on any recommendations expected from the SAP meeting, which reviewed the “use of new approach methodologies (NAMs) to derive extrapolation factors and evaluate developmental neurotoxicity for human health risk assessment.”  This is part of a larger and longer evaluation of whether test methods that avoid using test animals can reliably substitute for current test guideline requirements, that is, whether it is appropriate to rely on in vitro test protocols to substitute for current in vivo testing protocols.

EPA’s articulation at this point in time of mitigation needed if the FQPA 10x safety factor is retained may indicate a prediction about the SAP’s likely recommendations.  It will be important to monitor developments on this issue closely.

• Email This
• Print
• Comments

By Lisa M. Campbell, Timothy D. Backstrom, and James V. Aidala

In September 2020, the U.S. Environmental Protection Agency’s (EPA) Office of Pesticide Programs (OPP) plans to convene a Federal Insecticide, Fungicide and Rodenticide Act (FIFRA) Scientific Advisory Panel (SAP) meeting to discuss New Approach Methodologies (NAM) for organophosphate (OP) pesticides.  EPA states that these NAMs could reduce reliance on default uncertainty factors for human health risk assessment and also reduce animal testing.

Under Administrator Wheeler’s directive to prioritize efforts to reduce animal testing, EPA is developing NAMs based on in vitro techniques and computational approaches that will also provide the opportunity to incorporate information relevant to humans.  OPP states that it is evaluating use of “in vitro data for 16 organophosphate compounds to reduce potentially reliance on default risk assessment uncertainty factors in favor of more refined data-derived factors.”  Human health risk assessment for OP pesticides has recently been focused primarily on potential developmental neurotoxicity, and the Office of Research and Development (ORD) has been working to develop a NAM to evaluate developmental neurotoxicity.  Initial analyses of data derived from neuron cell models have been completed for specific OP pesticides as a case study and, when possible, compared to in vivo results (an in vitro to in vivo extrapolation).

This case study of a NAM for developmental neurotoxicity using OP pesticides will be presented to the FIFRA SAP at the September meeting for its consideration and advice.  EPA will request external review and public comment on this research before implementing NAMs in human health risk assessments.  Additional details, including dates, times and agenda, will be forthcoming at www.epa.gov/sap.

Commentary

EPA has for some time had a general policy that it will try to develop and to implement alternatives to in vivo animal testing.  These alternatives to animal testing are typically based on new in vitro assays and modeling methodologies.  It is interesting that OPP has selected an in vitro NAM to assess developmental neurotoxicity of OP pesticides as a case study, given the controversy surrounding EPA’s use of the default Food Quality Protection Act (FQPA) uncertainty factor for all OP pesticides, which was based primarily on epidemiology data that EPA claimed may suggest a link between chlorpyrifos exposure and developmental neurotoxicity.  Prior to this determination, human health risk assessment for OP pesticides was generally based on expert judgments by EPA that neurotoxicity would not be expected below the established threshold for acetylcholinesterase (AChE) inhibition, and that infants and children are not likely to be more sensitive to neurotoxic effects than adults.  OPP adopted the FQPA determination for all OP pesticides even though it could not determine or propose a mechanism for the presumed developmental neurotoxicity of chlorpyrifos below the threshold for AChE inhibition, or evaluate whether other OP pesticides might share a similar mechanism.  Since the 2015 release of the Literature Review, additional epidemiology studies have become available and a number of concerns regarding the reliability of the epidemiology data have been raised.  EPA has also expressed concerns with the availability and reliability of the epidemiology studies.  These developments bring into question the accuracy and reliability of the Literature Review.

In its announcement, OPP states that the new NAM is intended “to reduce potentially reliance on default risk assessment uncertainty factors,” although it does not state which uncertainty factors may be supplanted or modified.  Standard uncertainty factors which may be implicated include the factor for extrapolating from animal data to human effects (“interspecies variation”), the factor for human variability (“intraspecies variation”), and the default uncertainty factor for potential increased sensitivity of infants and children (“FQPA uncertainty factor”).  The issues may spark additional controversy.  Additionally, even if OPP and the FIFRA SAP conclude that the proposed NAM for developmental neurotoxicity is a viable approach to human health risk assessment for OP pesticides, there are likely to be many related policy issues.  For example, it is unclear whether OPP would be sufficiently confident in the reliability of such an assay to propose cancellation or suspension of affected pesticide products based on a resultant human health risk assessment.

• Email This
• Print
• Comments

By Lisa M. Campbell, Timothy D. Backstrom, and James V. Aidala

On February 6, 2020, Corteva Agriscience (Corteva), announced it will discontinue all production of the organophosphate (OP) insecticide chlorpyrifos by the end of the year.  Corteva and its corporate predecessor, Dow AgroSciences, have been the principal global manufacturers of chlorpyrifos.  Corteva announced that its decision to stop selling chlorpyrifos was based entirely on financial considerations.  This announcement came on the same day that Corteva had previously agreed it would end further sales of chlorpyrifos in California, and less than a week after the date the European Union (EU) ended all sales of chlorpyrifos in member states.  These actions followed a number of prior actions taken by other national and state governments to ban or severely restrict chlorpyrifos.  Corteva emphasized in its public statements that the science demonstrates that chlorpyrifos can be safely used, but that the company made a business decision based on the declining markets for the product.  In an interview reported by the Washington Post, Susanne Wasson, Corteva's President for Crop Protection said, “It’s a tough decision for us to make, but we don’t feel like it’s viable going forward.” In other statements, Corteva noted that in the last ten years their share of the global chlorpyrifos market had declined from 75% to less than 20%.

Chlorpyrifos has been registered for use in the U.S. for over 50 years, but has become increasingly controversial in the dozen years since the Pesticide Action Network of North America and the Natural Resources Defense Council filed a petition in 2007 to cancel all registrations and revoke all tolerances for chlorpyrifos.  Following a protracted court battle and a decision by the Ninth Circuit Court of Appeals to force the U.S. Environmental Protection Agency (EPA) to take final administrative action concerning the 2007 petition, EPA proposed near the end of the Obama Administration to revoke all existing tolerances for chlorpyrifos.  A significant basis for this proposal was a controversial decision by a panel of EPA scientists that the default tenfold safety factor established by the Food Quality Protection Act (FQPA) for infants and children, which EPA had previously waived based on studies establishing a threshold for acetylcholinesterase (AChE) inhibition, should be reinstated.

The new EPA safety factor determination was based in large measure on epidemiology studies that reported an association between exposure to chlorpyrifos at levels below the presumed threshold for AChE inhibition and adverse neurodevelopmental effects in children.  Many industry scientists disputed the scientific basis for this EPA determination because confounding exposures and methodological biases in the epidemiology studies may have influenced the reported association with neurodevelopmental effects and because the EPA determination made unprecedented use of epidemiology data.  Beyond the effect on chlorpyrifos, the EPA decision will likely continue to be controversial because EPA included a similar safety factor determination for all OP pesticides, even though the mechanism responsible for the reported neurodevelopmental effects attributed to chlorpyrifos has not been identified and the other OP products were not studied in the epidemiology studies.

In the first year of the Trump Administration, EPA Administrator Scott Pruitt decided not to adopt EPA’s previously proposed tolerance revocation and instead to deny formally the 2007 petition, citing unresolved scientific issues.  This reversal of course, however, was not accompanied by any new scientific assessment or by any explicit revision of the prior FQPA safety factor determination.  Later, the California Department of Pesticide Regulation (DPR) decided to designate chlorpyrifos as a Toxic Air Contaminant, a decision that was noteworthy because it was based primarily on new toxicology studies that DPR stated reported neurodevelopmental effects well below the threshold for AChE inhibition.  DPR deemphasized the epidemiology data relied on in the EPA safety factor determination in its decision.  Although EPA later stated that it would address these new toxicology studies as part of an accelerated registration review process, there were intervening decisions by the EU and by California to ban new sales, which may have contributed to Corteva’s February 6, 2020, decision to cease chlorpyrifos production.

Commentary

The decision by Corteva to cease manufacturing chlorpyrifos reminds us that the decision to continue marketing any chemical substance cannot be based solely on the scientific data, but must also consider the regulatory climate and the economic viability of the product.  For those of us with a long memory, the decision by Corteva is reminiscent of the decision nearly 40 years ago by the Dow Chemical Company to pull the plug on 2,4,5-T and silvex, after Dow had expended millions of dollars and many years of effort to contest an emergency suspension and subsequent cancellation of these herbicides.  Dow made this decision even though it believed that the available data demonstrated the safety of those products.

• Email This
• Print
• Comments

By Timothy D. Backstrom and James V. Aidala

On December 18, 2019, the Office of Pesticide Programs (OPP) of the U.S. Environmental Protection Agency (EPA) issued for comment a Proposed Interim Decision (PID) in the ongoing registration review process for each of the three registered triazine herbicides: atrazine, propazine, and simazine.  EPA will allow 60 days for comment on each of these triazine PIDs, but the specific comment deadline will only be established after EPA has published notice concerning the proposed interim decisions in the Federal Register.  EPA can utilize an “interim registration review decision” under 40 C.F.R. Section 155.56 whenever it is not yet ready to complete the registration review process, but EPA has nonetheless completed sufficient review to determine that new or interim risk mitigation measures are needed or that additional data or information should be submitted to complete the review.  For each of the three triazine herbicides, EPA is proposing to impose specific risk mitigation measures for particular registered uses to mitigate potential health and environmental risks.  For each triazine herbicide, EPA is not yet ready to make a final registration review decision because EPA has not made findings in the Endocrine Disruptor Screening Program (EDSP) or an effects determination under the Endangered Species Act (ESA).  Several key factors that will affect the final registration review decision for each of the triazine herbicides are discussed below.

Common Factors for Triazine Risk Assessment

There are several common factors to consider with regard to the triazines risk assessment.  These include:

1. Atrazine, propazine, and simazine are all included in the chlorotriazine chemical class.  EPA has determined that these three herbicides, along with three specific chlorinated metabolites, share a common mechanism of toxicity, so human health risks from all of these substances are being assessed by EPA together through one cumulative triazine risk assessment. The contribution of each product to aggregate human risk differs because of somewhat dissimilar use patterns. The combining of risks resulting from use of each triazine means, however, that it may be necessary for EPA to coordinate the ultimate registration review decisions for the three active ingredients.
2. As part of the ecological risk assessment for each triazine herbicide, EPA plans to make an effects determination for potentially vulnerable species under the ESA, which in turn will determine whether it is necessary for EPA to consult with the Fish and Wildlife Service or the National Marine Fisheries Service (the Services) concerning potential impacts of each active ingredient and relevant metabolites on endangered or threatened species.  Atrazine, propazine, and simazine are all included in a stipulated settlement between the parties in Center for Biological Diversity et al. v. EPA et al. No. 3:11 cv 0293 (N.D. Cal.), and EPA agreed in that stipulated settlement to set August 14, 2021, as the deadline for EPA to make a nationwide effects determination for each active ingredient, and to request any required consultation with the Services, under ESA Section 7(a)(2).
3. EPA states that the predominant human health effect of concern for all three of the triazine herbicides and their chlorinated metabolites is potential suppression of the luteinizing hormone (LH) surge, which is considered to be both a neuroendocrine and a developmental effect.  Atrazine and simazine were both included on List 1 for screening testing under the EDSP required by the Food Quality Protection Act (FQPA) amendments.   All of the required Tier 1 screening assays for each of these substances are complete and have been evaluated by EPA, but EPA has not yet made human health or environmental findings under the EDSP.  The EDSP screening testing has not been completed yet for propazine.

Risk Mitigation Measures

Each PID proposes specific risk mitigation measures intended to address potential human and environmental risks identified by the EPA risk assessments.

For atrazine, the PID includes the following measures to mitigate aggregate human risk:

• Reduce the permissible application rates for use of granular and liquid formulations on residential turf.
• Require additional personal protective equipment (PPE) and engineering controls for certain uses.
• Restrict aerial applications to liquid formulations only.
• Limit backpack sprayer applications to landscape turf to spot treatment only.
• Prohibit pressurized handgun application to certain commodities.

To mitigate ecological risks, the atrazine PID proposes to require various spray drift reduction measures, to add a non-target advisory statement to labeling, and to adopt a nationwide stewardship program.

For propazine, the PID proposes to cancel the greenhouse use to mitigate aggregate human risk.  Ecological risks would be mitigated by proposing to require various spray drift reduction measures and by adding a non-target advisory statement to labeling.

For simazine, the PID includes the following measures to mitigate aggregate human risk:

• Cancel simazine use on residential turf.
• Require additional PPE and engineering controls for certain uses.
• Limit pressurized handgun applications to certain commodities to spot treatment only.

Ecological risks would be mitigated by proposing to require various spray drift reduction measures and by adding a non-target advisory statement to labeling.

Commentary

In each of the PIDs for the triazine herbicides, EPA has focused its efforts on adopting mitigation measures which should be efficacious in reducing human and ecological risks without materially impairing the availability of the products in question for key agricultural uses.  In some instances, the PID documents explicitly state that the product registrants have agreed to proposed changes.  An EPA Pesticide Program Update dated December 19, 2019, that discusses the interim decision for atrazine includes statements of support from several grower groups.

• Email This
• Print
• Comments

By Lisa M. Campbell, Timothy D. Backstrom, and James V. Aidala

On August 2, 2019, the U.S. Environmental Protection Agency (EPA) Office of Pesticide Programs (OPP) announced that it has decided to reduce the Food Quality Protection Act (FQPA) safety factor for infants and children for pyrethroids from its current value of 3X to a new value of 1X.  This decision is based on a July 1, 2019, OPP report entitled “USEPA Office of Pesticide Programs’ Re-evaluation of the FQPA Safety Factor for Pyrethroids: Updated Literature and CAPHRA Program Data Review.”  Risk assessments incorporating the new lower FQPA safety factor for pyrethroids will be utilized in developing proposed registration review decisions for these compounds, and EPA has stated it will be taking public comment on the OPP report reducing the FQPA safety factor for pyrethroids after EPA publishes a notice of availability for the proposed registration review decisions.

Pyrethroids are a group of insecticides that includes natural pyrethrins (found in chrysanthemums) and more than 30 synthetic compounds with similar structure and activity. EPA has determined that it is appropriate to establish one FQPA safety factor for all pyrethroid active ingredients because these compounds all have the same mode of action and similar patterns of toxicity.  Pyrethroid insecticides are widely used in and around residential structures, on pets, in treated clothing, for mosquito control, and in various agricultural applications.  EPA indicates that although pyrethroids have relatively low mammalian toxicity, EPA believes that the principal concern for human risk assessment is a potential to cause acute neurotoxic effects.

The FQPA safety factor is intended to account for “potential pre- and post-natal toxicity and completeness of data with respect to exposure and toxicity to infants and children.”  The FQPA safety factor is set by statute at a default value of 10X, but EPA may select a lower value for this safety factor if EPA determines based on “reliable data” that such a lower value will be safe for infants and children.  This determination necessarily depends on EPA’s assessment of the quality of the data that address the susceptibility to adverse effects of the pesticide of infants and children.  Based on current EPA guidance, OPP evaluates the need for the default FQPA safety factor of 10X in two components: a safety factor of about 3X assigned to pharmacodynamic (PD) differences and a safety factor of about 3X assigned to pharmacokinetic (PK) differences.  PD differences refer to the sequence of events at the molecular or cellular level leading to a toxic response to a substance, while PK differences refer to absorption, distribution, metabolism, and excretion of the substance.

EPA previously evaluated the adequacy of the database concerning risks to infants and children posed by pyrethroid active ingredients in 2011.  At that time, EPA decided that there were sufficient data concerning the mechanism for potential neurotoxic effects of pyrethroids to allow EPA to reduce the factor for PD differences to 1X, but EPA retained the 3X factor for PK differences because EPA believed that the available pharmacokinetic data for pyrethroids was not sufficient for EPA to conclude that infants and children would not confront a greater risk of neurotoxic outcomes.  After EPA made the 2011 determinations, the Council for the Advancement of Pyrethroid Human Risk Assessment (CAPHRA) conducted a variety of additional research to address whether children are more sensitive to the neurotoxic effects of pyrethroid exposure, and this research assessed both PD and PK differences.  CAPHRA submitted a peer-reviewed physiologically based pharmacokinetic (PbPk) model for pyrethroids to EPA in 2018.  After reviewing the new CAPHRA data and the current public literature for pyrethroids, EPA has now concluded that the factor for PD differences should be maintained at 1X, but the factor for PK differences should be reduced from 3X to 1X.  Collectively, these determinations mean that EPA has concluded that there are reliable data to support a determination that infants and children are not more susceptible to the neurotoxic effects of pyrethroids than adults, so there is no need to retain either the default FQPA safety factor of 10X or the previous FQPA safety factor used for pyrethroids of 3X.

Commentary

The adoption by EPA of a new FQPA safety factor of 1X for all pyrethroid active ingredients will likely facilitate retention of existing use patterns and use directions for a large number of pyrethroid insecticides that are commonly used in and around human residences and workplaces.

From a larger perspective, the process by which EPA evaluated and selected a proposed FQPA safety factor for pyrethroids may be seen as typical for most pesticides or classes of pesticides.  The selection of a FQPA safety factor for a particular pesticide usually is based on review of available animal data, including PD and PK data, to determine whether there is any basis for concluding that infants and children may be more susceptible to adverse effects of that pesticide than adults.  Where EPA decides that the animal data addressing this question are insufficient, affected registrants and other proponents of registration can consult with EPA concerning studies that will address the uncertainties.  Depending on the outcome of such studies, EPA may be able to conclude that there is a scientific basis for a partial or complete reduction of the default FQPA safety factor.

Compared to this typical evaluation process, the recent decision by EPA to retain the default FQPA safety factor for all organophosphate (OP) active ingredients, which was based on EPA’s interpretation of neurodevelopmental effects reported at low exposure levels (below the threshold for acetylcholinesterase inhibition) in epidemiology studies for chlorpyrifos, may be seen as an aberration.  EPA’s decision to rely on epidemiology studies that may be susceptible to methodological biases, and the decision to utilize epidemiology studies for chlorpyrifos to set the FQPA safety factors for all OP pesticides, have both been controversial.

EPA’s recent decision to retain the current tolerances and registrations for chlorpyrifos was based in significant part on EPA’s interpretation of a PbPk model for chlorpyrifos previously submitted by DowAgro (now Corteva), which mitigated to some degree EPA’s retention of the default FQPA safety factor for chlorpyrifos.  Corteva may submit further data addressing PD and PK differences for chlorpyrifos, and EPA has also stated that it intends to review some new animal studies for chlopyrifos, which purport to show neurodevelopmental effects at low exposure levels.  Perhaps these data will allow EPA to establish a point of departure (POD) for chlorpyrifos risk assessment without any need for a further excursion into the unfamiliar risk assessment territory represented by EPA’s use of epidemiology data for chlorpyrifos.

• Email This
• Print
• Comments

By James V. Aidala and Margaret R. Graham

On September 28, 2018, the U.S. Environmental Protection Agency (EPA) announced it was accepting public nominations of scientific experts to be considered for ad hoc participation on the Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA) Scientific Advisory Panel (SAP) through membership on the Food Quality Protection Act (FQPA) Science Review Board (SRB).  83 Fed. Reg. 49091.  EPA states that “all nominees will be considered for ad hoc participation providing independent scientific advice to the EPA on health and safety issues related to pesticides”  and requests that any individuals nominated have expertise in one or more of the following areas:  biochemistry; chemistry; epidemiology; human health risk assessment; pathology; physiologically based pharmacokinetic (PBPK) modeling; aquatic modeling; pharmacology; ecological risk assessment; environmental exposure and fate; environmental toxicology; occupational, consumer, and general exposure assessment; toxicology; dose response modeling; environmental engineering; statistics; water quality monitoring; hydrologist; Geographic Information Systems (GIS) specialist; computational toxicology; entomology; veterinary entomology; medical entomology, insect ecology, allergenicity, research veterinarian; inhalation toxicology; volatile organics; endocrinology, alternative testing methods, high throughput testing approaches, adverse outcome pathways, cross species extrapolation, and systematic review.  The Designated Federal Officer’s to whom nominations should be provided is listed in the Federal Register notice.  Nominations are due by November 13, 2018. 

Commentary

FPQA added this SRB to the previous authorization for the SAP to recognize the expanding universe of scientific questions which often underlie issues surrounding pesticide registration.  The FQPA amendment simply adds that “60 scientists who shall be available to the SAP” without specifying any particular disciplines or skills which might be useful to assist with the deliberations and review by the SAP.  This was intended to continually allow EPA to adapt to changing or evolving scientific questions without constantly tinkering with the membership of the SAP itself.  At the same time, it allows these ad hoc members to be recognized for their contributions and to be compensated in the same manner as SAP members.  

• Email This
• Print
• Comments

By Lisa M. Campbell and Timothy D. Backstrom

On August 9, 2018, the majority of a three-judge panel of the U.S. Court of Appeals for the Ninth Circuit (Ninth Circuit) issued an opinion in the latest chlorpyrifos case (League of United Latin American Citizens (LULAC) v. Wheeler, No. 17-71636) granting the petition for review of a 2017 order by the U.S. Environmental Protection Agency (EPA) that denied an administrative petition to revoke the tolerances for chlorpyrifos; vacating the 2017 order; and remanding the matter back to EPA with explicit directions to EPA to “revoke all tolerances and cancel all registrations for chlorpyrifos within 60 days.”  A separate dissent stated that the court should have dismissed the case for lack of jurisdiction.  Please see our blog item “EPA Denies Petition to Ban Chlorpyrifos” for more information on EPA’s denial of the petition in 2017.

EPA argued in its brief that the court lacks jurisdiction to review the 2017 order denying the petition to revoke the tolerances for chlorpyrifos because Section 408(g)(2)(C) of the Federal Food, Drug, and Cosmetic Act (FFDCA) requires EPA to rule on administrative objections to its denial of the petition to revoke the tolerances for chlorpyrifos before judicial review is available under FFDCA Section 408(h)(1).The majority opinion rejected this argument, stating that FFDCA Section 408(h)(1) “does not ‘clearly state’ that obtaining a section (g)(2)(C) order in response to administrative objections is a jurisdictional requirement.” Rather than a jurisdictional limitation, the majority construed the objections process in FFDCA as a non-jurisdictional “claims-processing rule.”In contrast, the dissenting judge agreed with EPA’s argument that the court lacks jurisdiction to review this matter until after EPA responds to the objections to the 2017 order.

After concluding that the objections process is not jurisdictional in character, the majority next considered whether the petitioners should nonetheless be required to exhaust their administrative remedies by waiting until EPA responds to their objections before obtaining judicial review.Although FFDCA Section 408(g)(2)(C) requires EPA to rule on the objections “as soon as practicable,” EPA had taken no action for 13 months after the objections were filed.The majority concluded that the exhaustion requirement should be waived “in light of the strong individual interests against requiring exhaustion and weak institutional interests in favor of it.”

EPA did not specifically address the substantive merits of the 2017 order in its brief, and the majority found that EPA has consequently “forfeited any merits-based argument.”The 2017 order was issued in the context of an administrative record in which EPA has repeatedly determined that the FFDCA standard for maintenance of chlorpyrifos tolerances (“a reasonable certainty that no harm will result from aggregate exposure to the pesticide”) could not be met because of the risk of neurodevelopmental effects. The standard for registration under the Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA) incorporates this same FFDCA standard. Although the 2017 order stated that “the science addressing neurodevelopmental effects is unresolved,” it did nothing to alter these prior EPA determinations. The majority noted that EPA’s assertion that “significant uncertainty” remains regarding the health effects of chlorpyrifos being directly at odds with the “reasonably certainty” standard and “therefore mandates revoking the tolerance under [FFDCA Section 408(b)(2)(A)(i)].” The majority concluded that the possibility that future evidence may contradict EPA’s current determinations cannot justify continued inaction, and that the failure of EPA to proceed with the revocation of the tolerances and the cancellation of the registrations for chlorpyrifos “has now placed the agency in direct contravention of the FFDCA and FIFRA.”

Commentary

The court’s direct instruction requiring EPA to proceed promptly with revocation of all tolerances and cancellations of all registrations for chlorpyrifos represents an unusually aggressive judicial intervention in the administrative process.Nevertheless, this outcome must be viewed in the context of an eleven year history beginning with an administrative petition that requested the same relief, followed by a writ of mandamus in 2015 from the same court requiring EPA to make a prompt decision on the petition.Although substantial controversy remains concerning the correct interpretation of epidemiology studies with chlorpyrifos, it appears that the court believes that EPA has not taken any action that would support a change in EPA’s prior conclusion that these studies constitute evidence of potential neurodevelopmental effects in children at chlorpyrifos exposure levels below the threshold for acetylcholinesterase (AChE) inhibition. Had EPA’s 2017 denial of the administrative petition been accompanied by an amended risk assessment for chlorpyrifos which articulated a changed conclusion, the court may have been less likely to substitute its judgment for that of EPA.The court seemed to find that because the scientific assessments in the current administrative record could not support the “reasonable certainty” standard in the FFDCA, the conclusion it reached on the merits was unavoidable.

Please see our blog item “Oral Argument Held in Case Challenging EPA’s Denial of Petition to Revoke Chlorpyrifos Tolerances” for information on the oral argument that took place on July 9, 2018, and the briefing in this case.  Further information on the case proceedings is available on our blog under key word chlorpyrifos.

• Email This
• Print
• Comments