A new study by researchers from the University of California Los Angeles (UCLA) and UC Irvine has found that the pesticide methyl bromide remains in use in 36 of California’s 58 counties, including both urban and rural areas. The chemical, recognized as a developmental, neurologic, and respiratory toxin, continues to be used for fumigating freight containers and shipping needs despite its phaseout for most agricultural purposes in 2015.
Methyl bromide was recommended for phaseout by the U.S. government in 2005 due to its health and environmental risks, such as cancer, respiratory problems, and damage to kidneys, skin, and liver. The study “Exceptional use: examining methyl bromide applications in California 2016–2022,” published in Environmental Research Communications, focuses on continued non-agricultural uses.
The research indicates significant exposure risks near port cities like Long Beach and Los Angeles neighborhoods such as Wilmington and San Pedro. Air monitoring between 2023-24 showed average levels of methyl bromide at 2.1 parts per billion (ppb) in western Long Beach—nearly double the state’s recommendation of 1.2 ppb—with some days recording even higher values.
“These levels translate to a ‘hazard quotient’ of 1.6; values greater than 1.0 suggest an increased risk of negative health effects, and, in fact, we found exposures — on at least two occasions — reached hourly levels of more than 900 ppb,” said Yoshira Ornelas Van Horne, assistant professor at UCLA Fielding School of Public Health’s Department of Environmental Health Sciences. “It is worth noting this same neighborhood is home to an elementary school, 600 homes and parks, and is already ranked by the state as being in the top 25th percent of environmental hazards.”
The report notes that children face greater risks compared to adults because they inhale more air relative to their body weight. However, there has been little investigation into children’s exposure to fumigation pesticides.
“Research in rural, agricultural communities have seen an association between proximity to agriculturally applied methyl bromide and restricted fetal growth,” said Jill Johnston, study co-author and associate professor at UC Irvine’s Joe C. Wen School of Population and Public Health. “Additionally, studies in California have found that an increase in the ambient air concentration of methyl bromide is associated with increased risk of emergency department visits for asthma among children.”
From 2016–2022 methyl bromide was used across counties with over 35 million residents statewide. In agricultural counties like Siskiyou or Merced it was mainly used for soil fumigation or nursery operations; however Los Angeles County saw primary use tied to commodity/shipping fumigation.
“Freight transported in containers is typically fumigated as a means to reduce potential infestations or inhibit the spread of pests,” Johnston said. “In the United States, foreign freight containers with certain produce such as grapes must be treated for pests—and in most cases—methyl bromide use is allowed at permitted facilities. These are important precautions but the reality is there are potential alternatives…that pose lower health risks.”
Researchers highlighted data limitations due to sparse monitoring systems—such as only one monitor providing regional data since 2023 around Long Beach—but called for better coordination among federal,state,and local agencies.More comprehensive monitoring,warnings,and efforts toward replacing MeBr with less toxic alternatives were also recommended.
“This work highlights the ongoing challenge of addressing community health concerns due to fumigation activities,and lackof comprehensive healthand safety assessments,” Ornelas Van Horne said.“Itis clear the potential health burdensfor continued MeBr useare concentratedin areas nearfumigation activitieslikeLong Beachandthe portareas,butitisequallycleartherearegapsininformationandover sightthatneedtobeaddressed;people’s healthisatrisk.”
The study relied on records from multiple databases maintained by state agencies—including California DepartmentofPesticideUseRegistryandCaliforniaAirResourcesBoard—as wellaslocaldatafromLosAngelesandLongBeachports,andfederalrecordsfromtheUnitedStatesDepartmentofAgriculture.Mappingandanalysistoolswereusedtoidentifyusagepatterns.Theworkwas supportedbyfacultyandstaffatUCLAandUCIwithfundingpartlyfromtheUSNationalInstitutesofHealth.
UCLA serves as a major public research institution offering diverse academic programs across various disciplines while emphasizing knowledge creation for societal benefit according tothe official website. It draws students,scholars,and partners locally,nationally,and internationally.[source]
