Human Exposure

People are exposed to toxic chemicals by eating contaminated foods (especially fish), breathing polluted air, and absorbing chemicals through the skin. For average Americans, chemical exposures are involuntary, unsuspected, and are a result of our inadequate regulatory system regarding toxic chemicals which has not been updated in 40 years.

Chemicals in Food: Are Fish Safe to Eat?

In 2004, we conducted a study of chemical contaminants (PCBs, pesticides, and PBDE flame retardants) in farm-raised salmon from Maine, eastern Canada, and Norway, and in wild salmon from the Pacific coast. As expected, contaminants were much higher in farm-raised salmon fed a high-fat diet than in the leaner wild Pacific salmon.

At the time, a paradigm prevailed: if you cut off the skin and underlying fat, you remove the chemicals. Our study showed that this paradigm was not true.

Removing the skin does not reduce the chemicals in farmed salmon because the flesh is “marbled” with chemical-laden fat cells

This study had policy implications and called for transparent labelling of farm-raised salmon in the marketplace.

Our subsequent study looked at brominated flame retardants (PBDEs and HBCDs) in seven species of commercially important fish stocks along the US Atlantic coast - including Atlantic herring, mackerel, hake, and flounder. A key finding was: flame retardants are biomagnifying in the food web, implying that fish marketed for human consumption are a source of chemicals known to cause numerous adverse health effects and cancer in animals and people.

PBDEs in Farmed Salmon
PCBs Dioxins in Farmed Salmon
BFRs in NW Atlatic Marine Food Web

Indoor Contaminants: Halogenated Flame Retardants

For most Americans, our exposure to flame retardants and other indoor contaminants mainly occurs through inhalation of house dust that concentrates the chemicals released from foam furniture, plastics, and other synthetics. Children have higher levels than adults because they ingest chemicals in dust from hand-to-mouth contact.

After decades of research on the commonly used brominated flame retardants (PBDEs), it was found that the benefits of treating household furniture with these chemicals had been overstated and their health hazards, especially developmental toxicity in children exposed early in life, were undeniable. In 2010, Institute Director Dr. Shaw was the lead author on a pivotal review paper Halogenated Flame Retardants: Do the Benefits Justify the Risks? This landmark paper challenged the efficacy of these chemicals in preventing fire deaths and presented a large body of scientific evidence of the negative health effects in animals and human, including cancer, that are associated with exposure. The paper had national policy implications, laying the groundwork for the San Antonio Statement, published in the NIEHS journal Environmental Health Perspectives, which cited the need for regulatory action on halogenated flame retardant chemicals worldwide. It was signed by more than 300 scientists from 30 countries, and accompanied by an editorial by the NIEHS Director. Subsequently the Chicago Tribune brought the issue to public attention in its 2012 award-winning series revealing industry’s campaign to downplay clear evidence of health risks of exposure to the public.

The San Antonio Statement and Editorial
Brominated Flame Retardants and Their Replacements in Food Packaging and Household Products: Uses, Human Exposure, and Health Effects

Occupational Exposure and Cancer Risk Among Fire Fighters

Fire fighters experience a much higher level of exposure to indoor chemicals than the general population. Studies show that fire fighters experience significant occupational exposure to carcinogens and their cancer risk increases significantly with the duration of firefighting.

Fire fighters have elevated rates of as many as 14 site-specific cancers that are thought to be related to their occupational exposure to carcinogens, including digestive, oral, respiratory and urinary system cancers; multiple myeloma, non-Hodgkin’s lymphoma, leukemia, malignant melanoma, and prostate, testicular, brain, and breast cancer (among women).

Fires today are more toxic than in the past due to the prevalence of chemically-treated contents in homes and buildings – foam furniture to plastics, electronics, textiles, and insulation. When organic chemicals such as flame retardants burn, large amounts of carcinogenic combustion byproducts are released into soot and smoke, which fire fighters inevitably inhale, ingest, or absorb through their skin. 

The San Francisco Firefighter Study

The Institute is currently initiating the National Firefighter Cancer Biomarker Study to advance understanding of the possible links between occupational exposure and cancer risk among firefighters across the country. Although strongly suspected, a causal relationship between firefighting exposure and cancer risk has not been proven. The research will strengthen measures to protect firefighters from harmful exposures and will inform public policy.

This landmark study builds upon our recent pilot study that identified several chemicals with mutagenic and carcinogenic potential in the blood of fire fighters after a fire event in San Francisco. This study was the first to measure brominated flame retardants (PBDEs) and their combustion by-products – dioxins and furans – in firefighters, and demonstrated that exposure to these chemicals during fires may carry even higher risks for cancer and other health problems than already demonstrated. In some individuals, the levels of combustion by-products – brominated dioxins and furans – were 100 times higher than in average Americans.

The pilot study, titled "Persistent Organic Pollutants including Polychlorinated and Polybrominated Dibenzopdioxins and Dibenzofurans in from Northern California" and in Chemosphere, can be viewed here

For more information about cancer risk among fire fighters, see:

Shaw et al. (2014). Is Firefighting Carcinogenic? Chemical Exposure and Cancer Risk Among Fire Fighters (Shaw et al Firefighter and Cancer Study Poster.)

The Hill Blog: A burning issue for fire fighters: Flame retardants and cancer

From Laboratory to Legislature

The Institute’s research findings have been shared with the policymakers and with fire fighters across the country – from Maine to Washington state.

In September, 2014, Dr. Shaw appeared at a press conference with Senator Chuck Schumer in Albany, NY, in support of his bill, The Children and Fire Fighter Protection Act that would ban the ten most toxic flame retardants in household furniture and children’s products. Senator Schumer praised our 2013 study of California fire fighters for alerting the nation to the dangers fire fighters face from flame retardant chemicals.

In May, 2015, Dr. Shaw’s testimony before the Minnesota legislature helped pass the strongest flame retardant bill in the country. The Firefighters’ and Children’s Protection Act will effectively ban the use halogenated flame retardants in children’s products and residential furniture. The bill also stipulates that replacement chemicals in these items may not be immune or reproductive toxins or carcinogens.

Dr. Susan Shaw is the “godmother” of research on chemical exposure and cancer among fire fighters, the science driving our safe chemicals legislation to protect all Americans.”

Senator Chuck Schumer, (D-NY)