Bergeson & Campbell, P.C. serves small, medium, and large pesticide product registrants and other stakeholders in the agricultural and biocidal sectors, in virtually every aspect of pesticide law, policy, science, and regulation.

By Lisa M. Campbell and Lisa R. Burchi

On May 8, 2019, the California Environmental Protection Agency (CalEPA) announced that the California Department of Pesticide Regulation (DPR) will be initiating cancellation proceedings of chlorpyrifos.  In its press release, CalEPA states that the decision to commence cancellation proceedings “follows mounting evidence, including recent findings by the state’s independent Scientific Review Panel on Toxic Air Contaminants, that the pesticide causes serious health effects in children and other sensitive populations at lower levels of exposure than previously understood.”

DPR’s decision, following years of review in California of chlorpyrifos, is sure to garner significant controversy, comments, and, potentially, litigation.

Background

Chlorpyrifos first entered the comprehensive risk assessment process after being designated by DPR with a “high” priority status in 2011, and some of the DPR documents supporting the current action were issued in 2011.

In December 2015, DPR released a draft risk assessment for public comment.  Since the risk assessment identified potential human exposure to spray drift (via inhalation or deposition) as a concern, DPR entered chlorpyrifos in its formal evaluation process to determine the scientific evidence for listing it as a pesticide Toxic Air Contaminant (TAC) (CA Food & Agric. Code §§ 14021-14027).

DPR’s assessments were intended to evaluate chlorpyrifos as a pesticide TAC as defined in California regulations (Title 3, Section 6864).  The determination of a pesticide TAC is based on whether the air concentrations, either measured or modeled, exceed the reference concentration (RfC) divided by ten.  Under the applicable California statutory provisions, designation of an active ingredient as a TAC is based on an evaluation that assesses the following:

  • The availability and quality of data on health effects;
  • The potency, mode of action, and other relevant biological factors;
  • An estimate of the levels of exposure that may cause or contribute to adverse health effects; and
  • The range of risks to humans resulting from current or anticipated exposure (CA Food & Agric. Code § 14023(a)).

DPR published its draft revised report entitled "Evaluation of Chlorpyrifos as a Toxic Air Contaminant" in December 2017 and an addendum to that report in June 2018.  DPR issued its final TAC evaluation in July 2018.  The July 2018 evaluation concludes that “chlorpyrifos meets the criteria of TAC designation by using either the developmental neurotoxicity endpoint or the [acetylcholinesterase (AChE)] inhibition endpoint, even without the additional 10x uncertainty factor necessary to account for the fact that the developmental neurotoxicity effects occur at a lower level than AChE inhibition.”

DPR’s findings, public comments, and responses to those comments were reviewed by the Scientific Review Panel (SRP) on TACs.  SRP’s findings on chlorpyrifos issued in August 2018 “unanimously concluded that the report, with the revisions requested by the Panel, is based on sound scientific knowledge, and represents a balanced assessment of our current scientific understanding.”

In April 2019, chlorpyrifos was listed in California as a TAC, which triggered a DPR requirement to “develop control measures to protect the health of farm workers and others living and working near where the pesticide is used.”  In its press release announcing the cancellation proceedings, CalEPA states that “DPR has determined, in consultation with CDFA, the Office of Environmental Health Hazard Assessment (OEHHA), and the California Air Resources Board (CARB), that sufficient additional control measures are not feasible.”

Commentary

DPR’s announcement is the beginning of what DPR estimates could be a two-year cancellation proceeding, although in reality the process may take even longer.  Other actions proposed in conjunction with the cancellation proceeding include:

  • DPR to consult with county agricultural commissioners and local air pollution control districts before filing for cancellation.
  • DPR to support “aggressive” enforcement of existing restrictions on the use of chlorpyrifos, including a ban on aerial spraying, quarter-mile buffer zones, and limiting use to crop-pest combinations that lack alternatives.
  • DPR and CDFA to convene a cross-sector working group to identify, evaluate, and recommend safer and more practical and sustainable alternative pest management solutions to chlorpyrifos.
  • California Governor Gavin Newsom to propose $5.7 million in new budget funding “to support the transition to safer, more sustainable alternatives.

DPR’s action must also be viewed in conjunction with various federal and state reviews and resulting litigation regarding chlorpyrifos’ continued registration and use.  The U.S. Environmental Protection Agency (EPA) for example, is conducting its own registration review of chlorpyrifos, and was ordered by the U.S. Court of Appeals for the Ninth Circuit to issue, within 90 days of the April 19, 2019, order, its final decision regarding the continued registration of chlorpyrifos.

Other states are also taking action to ban chlorpyrifos, notably Hawaii, which enacted legislation in 2018 to ban the use of chlorpyrifos in Hawaii by 2022; and New York, whose legislature approved bills in April 2019 to ban chlorpyrifos use in New York by 2021.

Stakeholders should review all these issues closely, as these unprecedented decisions are likely to provide multiple opportunities to comment or otherwise participate to ensure that regulatory requirements are indeed being met for cancellation. 

More information concerning chlorpyrifos is available on our blog.


 

By Timothy D. Backstrom and Lisa M. Campbell

On September 19, 2018, the California Department of Pesticide Regulation (DPR) proposed a regulation to designate chlorpyrifos as a toxic air contaminant (TAC).  DPR states that this proposal is being presented “after an extensive period of scientific and public review.”  The proposed rule is based on a final evaluation issued in July 2018, in which DPR’s Human Health Assessment (HHA) Branch determined that chlorpyrifos meets the quantitative criteria for designation as a TAC.  To make that determination, DPR utilized an inhalation reference concentration (RfC) based on new animal studies with chlorpyrifos that reported neurodevelopmental effects at exposure levels well below the threshold for acetylcholinesterase (AChE) inhibition.  More information on DPR’s final TAC evaluation is available in our blog item "California DPR Releases Final Toxic Air Contaminant Evaluation for Chlorpyrifos."  In August 2018, DPR posted the Scientific Review Panel on TAC’s findings on chlorpyrifos and the Director’s Proposed Determination Concerning Chlorpyrifos as a TAC.

DPR is providing a 45-day public comment period (until November 9, 2018) on the proposed regulation to list chlorpyrifos as a TAC.  Written comments may be submitted to .(JavaScript must be enabled to view this email address).  In addition, DPR is holding a hearing to receive oral comments on this issue on November 8, 2018, at 2:00 p.m. (PT) at the California Environmental Protection Agency headquarters, 1001 I Street, in Sacramento, California.  DPR states that it anticipates that the proposed regulation to list chlorpyrifos as a TAC will be effective in 2019.  Even though DPR is proposing to list chlorpyrifos as a TAC, DPR states that “possible mitigation measures to protect human health and the environment will be considered through a subsequent process involving consultation with other state and local agencies including the Office of Environmental Health Hazard Assessment (OEHHA) and the California Air Resources Board (CARB).”

Commentary

The U.S. Environmental Protection Agency (EPA) previously issued a determination that the default 10X safety factor for infants and children established by the Food Quality Protection Act (FQPA) should be retained for chlorpyrifos.  This determination was based primarily on epidemiology studies that purported to show adverse neurodevelopmental outcomes in humans at exposure levels below the threshold for AChE inhibition, but the methodology used in these epidemiology studies has been harshly criticized by the pesticide industry.  In contrast, the DPR TAC proposal is predicated on a determination that new animal studies with chlorpyrifos report neurodevelopmental effects below the threshold for AChE inhibition, and DPR views the epidemiology studies utilized by EPA to make its FQPA determination as providing corroboration for the animal data.  At this juncture, it is not clear how EPA will characterize the new animal data concerning chlorpyrifos.  In any case, questions are likely to remain concerning EPA’s use of data concerning chorpyrifos to establish the FQPA safety factor for other organophosphate (OP) pesticides.

More information on chlorpyrifos issues and California DPR regulations is available on our blog.


 

By Lisa M. Campbell and Timothy D. Backstrom

In July 2018, the California Environmental Protection Agency’s Department of Pesticide Regulation (DPR), Human Health Assessment (HHA) Branch, issued its final toxic air contaminant (TAC) evaluation of chlorpyrifos.  This final TAC evaluation updates the December 2017 draft evaluation of chlorpyrifos as a TAC for the Scientific Review Panel (SRP) which updated the August 2017 draft and was reviewed by the SRP on TACs, and incorporates certain changes based on SRP recommendations.  As part of their review of the December 2017 draft, the SRP recommended “additional and detailed review of developmental neurotoxicity studies, in particular recent in vivo animal studies as well as a more in depth analysis of human effects of chlorpyrifos” and “that DPR reevaluate the critical endpoints, the associated [(uncertainty factors (UF)], and the resulting [reference concentrations (RfC)] and [reference doses (RfD)] for each endpoint.”

DPR determines that a pesticide is a TAC for a non-cancer adverse effect if the projected air concentrations associated with use of the pesticide are more than one tenth of the inhalation RfC established based on animal toxicity and epidemiology data.  In the draft TAC evaluation for chlorpyrifos, DPR utilized the threshold for red blood cell acetylcholinesterase (AChE) inhibition in humans and a target margin of exposure (MOE) of 100, including a factor of 10 intended to account for potential neurodevelopmental effects below the threshold for RBC AChE inhibition.  In the final TAC evaluation for chlorpyrifos, DPR increased the MOE for AChE inhibition to 300, based on deficiencies in the human inhalation parameters used to model the threshold for AChE inhibition.

In addition, the final TAC evaluation establishes a new No Observed Effect Level (NOEL) for neurodevelopmental effects in animal studies with chlorpyrifos reported at exposure levels well below the threshold for AChE inhibition.  Based on this NOEL, DPR has derived a new inhalation RfC for neurodevelopmental effects, using a standard MOE of 100 consisting of 10X for interspecies sensitivity and 10X for intraspecies variability.  This new inhalation RfC based on neurodevelopmental effects in animal studies is about one-half the revised inhalation RfC based on the threshold for AChE inhibition.  Because the modeled spray drift air concentrations for chlorpyrifos are more than one tenth of this new inhalation RfC, DPR concludes “that chlorpyrifos meets the criteria to be listed as a TAC pursuant to the law of California.”

Commentary

In the final TAC evaluation for chlorpyrifos, DPR concluded that there is sufficient evidence from animal studies to establish a new NOEL for neurodevelopmental effects, which is well below the level that has been shown to cause AChE inhibition in the same animals.  Although the U.S. Environmental Protection Agency (EPA) has previously issued a determination that the default 10X safety factor for infants and children established by the Food Quality Protection Act (FQPA) should be retained for chlorpyrifos, this determination was based on epidemiology studies that purported to show adverse neurodevelopmental outcomes in humans at exposure levels below the threshold for AChE inhibition.  The methodology used in these epidemiology studies has been harshly criticized by the pesticide industry.  DPR views these epidemiology studies as providing corroboration, but the new DPR risk assessment is predicated instead on DPR’s view that animal studies with chlorpyrifos report neurodevelopmental effects below the threshold for AChE inhibition.  The DPR risk assessment based on these animal studies uses a standard MOE of 100.  How EPA may or may not view DPR’s conclusion is not known.  In light of the August 9, 2018, decision by the U.S. Court of Appeals for the Ninth Circuit (Ninth Circuit) directing EPA to proceed with revocation of all tolerances and cancellation of all registrations for chlorpyrifos, the effect of the DPR conclusion on EPA actions is not clear.  Nevertheless, it is worth noting that, because the mechanism by which chlorpyrifos would cause such neurodevelopmental effects is unknown and is below the level that causes AChE inhibition, any presumption by EPA that other organophosphate (OP) pesticides may cause the same type of effects will likely be vigorously disputed by industry on scientific grounds.  

Please see our blog item Ninth Circuit Directs EPA to Revoke all Tolerances and Cancel All Registrations for Chlorpyrifos for more information on the Ninth Circuit’s August 9, 2018, decision.