The Office of Environmental Health Hazard Assessment, commonly referred to as OEHHA (pronounced oh-EEE-ha), is a specialized department within the cabinet-level California Environmental Protection Agency (CalEPA). OEHHA is the lead state agency for the assessment of health risks posed by environmental contaminants.
As the scientific adviser within CalEPA, OEHHA's work assists decision makers within CalEPA, the California Department of Public Health, and other agencies and non-governmental organizations (see below). This includes assessing health and environmental risks from:
OEHHA's current director is Dr. Kris Thayer, who was appointed by Governor Gavin Newsom on April 29, 2025.[1][2] Previously, Dr. Lauren Zeise directed OEHHA from 2015 until 2024.
Goals and responsibilities
OEHHA's goals as a governmental agency include:
Improve the quality of the public's health and the environment.
Advance the science for the evaluation of risks posed to the public health and environment, and provide risk assessment leadership for the State of California.
Provide high quality information about environmental health hazards to the public.[3]
Scientific responsibilities
OEHHA assesses the risk of environmental chemicals based on health considerations alone. In contrast, risk managers consider economic and technical feasibility as factors in their decisions. This separation is essential to prevent undue political influence on the evaluation of health risks. These factors are and should remain explicitly excluded from the assessment of risk. OEHHA plays a critical and unique role that allows for the separation of risk assessment and hazard evaluation from risk management with primary goal of protecting public health and the environment.
OEHHA's Top Ten
OEHHA' most recognizable contributions to public and environmental health are:
OEHHA's groundbreaking work that showed that chromium in drinking water causes cancer; this issue was publicized in the movie Erin Brockovich.
OEHHA's research was critical in passing legislation to ban toxic phthalates from children's toys in California.
OEHHA was the first agency to identify second-hand tobacco smoke as a causal factor in breast cancer in young women.
California's ban on two widely used toxic flame retardants was supported by OEHHA's research. The California ban led to these chemicals being phased out in the United States.
In the face of strong opposition, OEHHA was the first government agency to establish that diesel exhaust causes cancer and induces asthma in children. OEHHA's work has led to stringent new controls on this widespread pollutant.
OEHHA has compiled the most comprehensive list in the world of chemicals that cause cancer, infertility, birth defects (known as the Proposition 65 list). Governments throughout the world rely on this list to regulate toxic chemicals. Manufacturers of consumer products use the list to design safer consumer products.
With OEHHA's ongoing support, the California Attorney General has led the way in removing lead from consumer product' including venetian blinds, children's toys and jewelry, tableware, water faucets and ceramics. Other California success stories include reducing the use of toxic pesticides in flea collars and no-pest strips and removal of a cancer-causing chemical from office supplies.
OEHHA maintains a list of hazardous arts and crafts supplies that contain toxic substances which pose health dangers to children. California elementary schools are prohibited from purchasing these materials. OEHHA also provides advice on the selection and use of safer art supplies.
OEHHA's research contributed to the phase-out of a toxic gasoline additive (MTBE) that contaminated groundwater throughout California.
California was the first state to regulate a rocket fuel component which widely contaminates drinking water and produce including lettuce. OEHHA's research provided the basis for this drinking water standard.
Traditional roles
OEHHA's work products cover a variety of environmental media. Traditionally OEHHA has focused on four primary areas:
Air pollution
Health-based air quality standards for pollutants associated with smog
Health effects assessments for toxic air contaminants
List of toxic air contaminants that disproportionately impact children
Indoor air guidelines for green building
Water pollution
Fish consumption advisories including warnings for pregnant women and children
Health protective levels for contaminants found in drinking water
Proposition 65: Carcinogens and Reproductive Toxicants
Maintain Proposition 65 list of chemicals known to be carcinogens and reproductive toxicants
Health-based assessments of safe levels for Proposition 65 carcinogens and reproductive toxicants
Multimedia risk assessment
Assess human and ecological health risk from exposure to chemicals contaminating California sites or facilities
Multimedia evaluation of the health effects of fuels
More recently
In recent years OEHHA has taken on new mandates to address emerging environmental issues of particular concern to the California public:
Biomonitoring – Evaluation of priority chemicals for Biomonitoring in California
Green Chemistry – Identification of key hazards of chemicals for implementation of green chemistry laws
Occupational health – Advice on health-based occupational exposure limits
Dry Cleaning – Research on safer alternative methods for dry cleaning
Environmental Justice
Cumulative Impacts
Emergency response for release of hazardous chemicals
Evaluation of contamination from oil spills
Evaluation of chemical sprays used to control invasive species
Child-specific health-based reference doses used to evaluate toxic chemicals found at school sites
Climate change – Identification of health effects
Involved in the light brown apple moth controversy: Issued report on the complaints of adverse health effects after aerial spraying in Monterey and Santa Cruz.
The Division of Scientific Programs is composed of four scientific branches that correspond to the scientific duties:
Air and Site Assessment and Climate Indicators Branch
Community and Environmental Epidemiology Research Branch
Pesticide and Environmental Toxicology Branch
Reproductive and Cancer Hazard Assessment Branch
Employee composition
OEHHA's scientific responsibilities are fulfilled by a highly educated and trained professional staff of about 120 individuals. The staff include toxicologists, epidemiologists, biostatisticians and physicians; many have international reputations in their scientific fields. In fiscal year 2007–2008 OEHHA was budgeted for approximately $17.5 million[5] or 1/500th of 1% the state General Fund; $8 million is from the general fund.
Who uses OEHHA's science?
State agency users of information on issues of environmental and public health include:
Scientific community including non-governmental organizations (NGOs)
Industries in a range of disciplines
General public
History
OEHHA was established in its current form by Governor Pete Wilson on July 17, 1991 with the creation of Cal/EPA.[6] OEHHA originated in the 1950s for air epidemiology in the Department of Public Health and developed over time with increased public awareness of the environment. OEHHA is the smallest of the six boards, departments and offices within Cal/EPA. OEHHA has no regulatory authority but remains the risk assessment and scientific arm of Cal/EPA and provides health-protective scientific guidance for Cal/EPA. Additionally, OEHHA is the lead agency for Proposition 65 implementation, a ballot measure approved in 1986, titled The Safe Drinking Water and Toxic Enforcement Act of 1986. The highly experienced team of experts is well respected in the scientific community and has been built up over more than twenty years. The quality and depth of OEHHA's commitment to public health, the environment and sound science is illustrated by the scientific quality of the risk assessments produced.
OEHHA is headquartered in the Cal/EPA building in Sacramento and has an office in the Oakland Elihu Harris State Building. Before the state building was built, the Oakland office used to be located across from the University of California, Berkeley; OEHHA has maintained academic ties with this institution.
Attempted closure
In May 2009, Governor Arnold Schwarzenegger proposed to "eliminate and transfer the functions" of OEHHA (and other agencies) as part his May Revise for the 2009–2010 budget.[7] Details about the transfer of functions including mandates, funding, staff resources, and new head agency are limited. Elimination of OEHHA would have had a small impact on the budget problems because of several reasons: (1) OEHHA's budget is very small (1/500th of 1% of the General Fund, or 1/50,000th) compared to the state deficit; $8.3 million of OEHHA's budget is general fund (2) about half of OEHHA's budget is funded by special funds (e.g. Proposition 65, Biomonitoring) (3) state mandates that transfer to other agencies or departments will still require funding.
On June 2, 2009 the Budget Conference Committee convened a hearing for public comment on the Governor's budget proposal. The hearing is archived on video, the testimony on behalf of OEHHA begins at 3:49:11[12] The supporters of OEHHA proposed and alternative to keep OEHHA intact and save $8.3 million, OEHHA's general fund budget. The proposal includes alternative funding sources and also expands OEHHA with the addition of Department Pesticide Regulation's risk assessment activities, Department of Toxic Substances Control's hazard evaluation functions, and lead roles in the children's health initiative and the Cal/EPA portion of the biomonitoring program. The main argument against the Governor's proposal is that the science performed in OEHHA should be independent of policy decisions made by the other boards and departments of Cal/EPA.
Senate Environmental Quality Committee Hearing
On June 10, 2009, The Senate Environmental Quality Committee voted to recommend that OEHHA be kept intact and expanded with the addition of California Department Pesticide Regulation's risk assessment activities, California Department of Toxic Substances Control's hazard evaluation functions, and lead roles in the children's health initiative and the Cal/EPA portion of the biomonitoring program. The recommendation will be forwarded to the Budget Conference Committee. The vote was 3-2. Senator Ashburn voted against the expansion recommendation but also said, "The expertise that resides in OEHHA ought not to be dissipated throughout state government as the Governor proposes."
↑ "Strategic Plan: 2018 Update"(PDF). Office of Environmental Health Hazard Assessment California Environmental Protection Agency. 2018. Retrieved July 3, 2025. This article incorporates text from this source, which is in the public domain.
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