The Los Angeles fires have caused more than 12,000 structures to burn down, raising concerns of dioxin exposure and environmental contamination. Multiple fires in the LA area have taken the lives of 24 people so far as firefighters continue their attempts to contain them. Dioxins are toxic chemicals that form when products containing chlorine or carbon are burned.

The most well-known recent example of dioxin exposure is the 2023 East Palestine, OH train derailment. Local authorities called for a controlled burn of the vinyl chloride and other chemicals, forming dioxins and creating a polluted environment for residents. The HighWire reported about independent evaluator Scott Smith’s testing results as well as his work to test the environment in Conyers, GA after a pool supplies company caught fire in September. 

The EPA has a document warning about dioxins in the context of backyard burning. The document states, “Dioxins are highly toxic, long-lasting organic compounds. They are dangerous even at extremely low levels and have been linked to several health problems, including cancer and developmental and reproductive disorders.”

A new report about a devastating 2021 fire in Boulder, CO, provides more details regarding the potential impact of the LA fires. The Marshall fire in Boulder burned about 1,000 homes, less than 10% of the destruction that has occurred so far in LA. Nearby homes that didn’t burn down contained increased polycyclic aromatic hydrocarbons and volatile organic compounds (VOC), including dioxins, benzene, and formaldehyde.

The authors of the Marshall fire study surveyed residents about symptoms that they attribute to the fire. 55% of residents surveyed had symptoms six months after the fire. 33% had symptoms a year later, and about the same percentage continued to have symptoms two years later. The most common symptoms were “itchy or watery eyes (33%), headache (30%), dry cough (27%), sneezing (26%) and sore throat (23%).”

Another common symptom was having a strange taste in one’s mouth. All the symptoms were associated with residents who said their homes smelled different when they returned a week after the fire. 2.6% of respondents experienced nausea or vomiting six months after the fire, and 1% continued to experience the symptoms after one year. 8.3% experienced shortness of breath, and 4.7% had an allergic skin reaction six months after the fire.

In November, The HighWire reported about an EPA official’s admission that mistakes were made in responding to the East Palestine, OH train derailment. Mark Durno, the emergency response official, told a resident in leaked audio that there needs to be a “validated link” to prove that the toxic chemical exposure caused residents’ symptoms and adverse health conditions. According to Durno, the fact that the symptoms didn’t start until after the fire is not enough to prove causality.

In June 2023, CDC Medical Officer Art Chang said,  “There is no way to get rid of vinyl chloride from the body. There is no way to get rid of dioxins from the body. We may not know how to treat or get rid of vinyl chloride from the body but we know how to treat those cancers.”

During the Marshall fire in Boulder and East Palestine, OH train derailment are case studies that reflect the dangers of exposure to VOCs and dioxins; there has been no data collected regarding cancer diagnoses and other severe health conditions. This is because cancer takes a long time to develop, and it is extremely difficult to control for other confounding variables.

The EPA states, “Cancer does not develop immediately after you’ve had contact with a cancer-causing substance, or carcinogen. Often, it takes a long period of time, such as 15 to 30 years, before cancer is diagnosed after exposure to a carcinogen. This makes tracking what caused the cancer very difficult. Also, since people are exposed to so many substances every day, it is very difficult to determine which ones may have increased their risk for cancer.”

Durno acknowledged scientific research that is showing a “real phenomenon” of health issues resulting from “multiple exposures to low-level contaminants” but said there are “too many scientific uncertainties” for agencies to take regulatory power to keep residents from going back to their homes.

CBS News reported, “multiple evacuation zones were lifted [on Sunday] for both the Palisades fire and Eaton fire.” The fire department has multiple considerations when determining whether an evacuation order should be lifted, including the amount of infrastructure damage and public health.

The EPA has not issued a press release concerning the LA fires but has directed X users to guidance that recommends limiting time outdoors in smoky areas. The EPA also links to an air quality map that shows most of the LA area has good air quality. The area southeast of Santa Monica shows mostly “moderate” air quality, stating that “unusually sensitive people consider reducing outdoor activity” and people should “go inside to cleaner air if you have symptoms.”

The study from the Marshall fire in Boulder shows that homes do not prevent contaminated air from entering the household around gaps in doors, windows, and heating/cooling systems.

In addition to dioxin exposure through the air, there are concerns regarding agriculture. The EPA states, “Dioxins accumulate in the food chain. Airborne dioxins can settle onto feed crops, which are then eaten by domestic meat and dairy animals. Dioxins also can settle on waterways through soil erosion. These dioxins accumulate in the fats of animals, and then in humans when we consume meat, fish, and dairy products.”

The EPA doesn’t mention the potential contamination of vegetables, fruits, and nuts. Smith, the independent evaluator in East Palestine, found garlic that contained dioxin levels of 440 parts per trillion compared to 0.81 parts per trillion in the control garlic that was harvested before the train derailment.

Los Angeles County has over 1,000 farms and more than 57,000 acres of active farmland. That is less than 1% of the total agricultural production in the United States. Antelope Valley farms produce baby carrots, peaches, cherries, and alfalfa. The county produced 36,000 tons of alfalfa in 2019, which is primarily used as livestock feed.