The Department of Pesticide Regulation (DPR) has drafted a new regulation to further restrict the use of 1,3-dichloropropene (1,3-D), known by the brand name Telone.

Following uproar over the sudden ban of the insecticide chlorpyrifos in 2019, the administration has taken the standard regulatory path for the controversial fumigant 1,3-D. That has rebuilt some trust with agricultural commissioners and the industry—though the agriculture community maintains that the agency’s science is overly conservative and its justification for protecting public health is lagging.

“Reducing human health risks from 1,3-D exposure is a priority for the state,” said DPR Director Julie Henderson in a statement. “Taking action to strengthen restrictions on the use of 1,3-D to lower those risks is core to our mission of protecting human health and the environment.”

The regulatory actions were in response to a brief spike in 1,3-D off-gassing that was recorded by air quality monitors in Fresno County in 2020 and later in Kern County. DPR reasoned the fumigant could cause acute and chronic cancer effects at certain levels of exposure to residents and other bystanders.

Henderson explained to growers at the Almond Conference last month that the proposed regulation would reduce exposures in communities and establish a level of protections equivalent to applying impermeable tarps. In partnership with UC Davis researchers and CDFA, DPR developed a set of application methods to deploy when tarps are not an option.

Currently anyone applying the fumigant must incorporate a 100-foot setback from buildings for one week. Under the proposed measures, that would extend to 500 feet in winter. DPR would also limit applications to 80 acres or less and require injections to be at least 24 inches deep.

The proposal calls for increasing the standard for the soil moisture content, notching it up from 25% to 50% to better contain emissions. Growers can accomplish this by irrigating with three inches of water for as long as three days prior to application. Soil sensors can measure the moisture, though DPR has outlined how a soil ribbon test can determine the moisture using just a hand.

According to a DPR staff scientist, the measure would have the added benefit of reducing emissions of volatile organic compounds (VOCs). Environmental activists have pressed the Air Resources Board to adopt a regulation for slashing greenhouse gas emissions from fumigants and other pesticides and protect communities from local air pollutants.

Ruben ArroyoRiverside County Agriculture Commissioner Ruben Arroyo

DPR raised eyebrows in 2019, when the initial options proposed for a regulation ranged from standard practices to more extreme measures like 3,500-foot buffer zones, 40-acre limits, tarping for two weeks and setting a soil moisture standard of 70%.

The department then collaborated with commissioners and the industry on pilot projects to test the real-world applicability of such measures. DPR also engaged with the vendors that farmers often contract with for applications.

Over the years, the relationship with county agricultural commissioners grew strained, as the Newsom administration pushed for expanding the roles of DPR and commissioners in pursuing environmental justice goals. Yet Ruben Arroyo, the Riverside County agricultural commissioner and past president of the California Agricultural Commissioners and Sealers Association, viewed DPR’s approach to 1,3-D as a return to the normal process.

“This is what I'm used to,” he told Agri-Pulse. “As long as we have science to back up the mitigation measures and the regulations, then I would feel confident in my enforcement program.”

The additional measures would not be difficult to enforce through inspections, he explained. Arroyo stressed that California already has the safest and most effective pesticide use program in the world, with oversight from three agencies—DPR, commissioners and U.S. EPA.

“Nobody—for the size of California—has that many inspectors that do as many inspections as we do on a daily basis,” he said. “We have a permitting system, we have a use monitoring system and we have an inspection program.”

Renee Pinel, president and CEO of the Western Plant Health Association, appreciated that DPR went through a “thoughtful process” with modeling the science and engaged with the agriculture community, applicators and “nonscientific stakeholders.” Pinel was relieved to see the protocols were sensitive to different regions and soil types—rather than a one-size-fits-all approach. The cancellation of chlorpyrifos, in comparison, had “so much outside pressure that was incorporated into how that was handled.” She recognized DPR has to respond to public interest concerns and be proactive in preventing incidents through their regulations.

“We have not seen any demonstrated science indicating that additional safeguards are actually necessary,” she told Agri-Pulse. “But we also recognize—particularly in California's policy environment—that's not the only consideration that DPR has to operate under.”

She described the air monitoring detections as anecdotal and not demonstrating an obvious pattern.

Nancy Fowler-Johnson feared the regulation could put her family nursery out of business. The state requires a certain rate of fumigation for Fowler Ranch to ship their bareroot trees. She questioned how California could prevent invasive pests if it held imports to the same fumigation standards.

The nursery can still use methyl bromide under an exemption to the 2005 ban and chloropicrin, but setback limits have made them too difficult to use, since suburbs now encircle their 111-year-old farm near Lincoln. They have relied on 1,3-D, but a new setback requirement could be devastating.

“I'm all in favor of workers being safe,” said Fowler-Johnson, noting that 40 years ago applicators didn’t even wear masks.

The nursery applies the most impervious tarps and injects 1,3-D with an 18-inch shank to get to the roots. But the current setback requirements mean she can only cover two acres in some places.

Fowler-Johnson has tried several alternatives to fumigants—from drowning nematodes in two feet of water to using marigold tea. The most promising solution involves selective breeding to develop new rootstocks, but this could take decades.

1,3-D has been a reliable pre-plant fumigant for preventing nematodes, and farmers who pulled trees and vines during the drought will be turning to it when replanting some of those acres, according to Chris Reardon, who directs government relations for the California Farm Bureau.

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He worried about the logistical complexities with adding so many new costs and constraints on timing and acreage and hoped that comments farmers submit to DPR on the proposal over the coming week will offer the agency some insight into those challenges and lead to more flexibility in the regulation. Reardon, who spent a decade in leadership positions at DPR prior to his work with trade groups, said that stakeholder feedback on such a large regulatory package is enormously helpful to DPR.

California Farm Bureau Administrator Jim Houston shared concerns over setbacks and tarping, which he warned can be “really, really expensive.” Before the pandemic, tarps cost $1,000 per acre and that price has gone up since, while availability has dropped. Meanwhile, the State Water Resources Control Board has certified the world’s first environmental laboratory that tests for microplastics in drinking water, and Houston worried farmers are “going to get hammered” by the board for adding more plastic to the environment with the additional tarping.

The 1,3-D regulation, he argued, could create more problems than it attempts to fix and the agency should run a cost-benefit analysis on the proposal.

“There's not a lot of data to show that you have a problem with nonoccupational bystanders,” he said, adding that small urban farmers would be the most impacted by the requirements.

Bystanders, he explained, would face the greatest risk of pesticide drift in urban areas, where farmers often lease land and struggle with tight profit margins.

“How do these solutions address that problem?” he asked. “Do they do so in a fair way?”

Environmental justice advocates, however, decried DPR’s proposal as being unfair to farmworkers. The department hosted a brief discussion on the proposed rulemaking last month during the monthly meeting of its Pesticide Registration and Evaluation Committee. Activists blasted the proposal for excluding protections specific to occupational bystanders.

Jane Sellen, who co-directs Californians for Pesticide Reform, claimed DPR had ignored the same recommendation from CalEPA’s Office of Environmental Health Hazard Assessment (OEHHA). She argued that a 2018 court decision in a lawsuit her group filed “clearly directed DPR to develop a rule for occupational bystander exposure.”

OEHHA also proposed a cancer risk level that was 14 times more protective than DPR’s, according to the group’s organizing strategist, Mark Weller. He shouted at DPR staff in disbelief over the issue, calling it “mind boggling” for DPR to not raise the cancer risk level.

The encounter set the stage for an upcoming public listening session on the 1,3-D proposal on Jan. 18 in Sacramento and on Zoom. DPR is also taking comments submitted online until then.

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