Beware of Toxic Dioxin Exposure in Post-Fire Environments


By Sean M. Scott & Briana C. Scott

Once the fire department has extinguished a fire, restoration contractors are on-scene shortly thereafter to secure the property, do initial clean-up, and perform emergency services.

In this first phase of a fire restoration project, restorers often find themselves working in and amongst a vast array of hazardous gases and byproducts of incomplete combustion.  At this point, restoration contractors rarely conduct any type of hazardous material testing as this is usually done later, and only if the building is old enough to warrant it. Even if testing is deemed necessary, it is typically limited to asbestos and lead.

Every fire is unique, and the combustion byproducts depend largely on the types and quantities of materials that were burned. Materials may include plastics, polyvinyl chloride (PVC), insulating foams, fiberglass, adhesives, carpet, or a vast array of household products such as electronics, furniture, cleaning products, etc. Even the burning of a wool sweater creates hydrogen cyanide, which was a gas used in World War I as a chemical warfare agent. The list of potentially hazardous gases and chemicals created in a structure fire are endless.

A particular concern is one chemical that few in the restoration industry have ever even heard of that is present in most, if not all structure fires. Its scientific name is 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), better known as dioxin. Dioxin is so toxic that some consider it to be the second most toxic chemical known to man, second only to radioactive waste.

What are dioxins and how are they created?

Dioxins are environmental pollutants and are part of a family of compounds that share distinct chemical structures and characteristics. They are formed when products containing carbon and chlorine burn, especially plastic, paper, pesticides, or other products where chlorine is used in the manufacturing process. Dioxins can also be produced when fuels such as wood, coal, or oil burn.

Depending on the ambient temperature in a fire, dioxins can be adsorbed or chemically bound to smoke particles or remain in a vapor phase. Adsorption is when particles bond with one another, like how magnets bond with iron, rather than being absorbed like a sponge absorbs liquids.

Human health risks of exposure to dioxin

Sir Percivall Pott (1714-1788) was an English surgeon and the first scientist to demonstrate that cancer may be caused by an environmental carcinogen. In 1775, Pott found a correlation between chimney sweeps’ exposure to soot and a high incidence of a condition called “soot wart,” a cancer later found to be squamous cell carcinoma. The cancer primarily affected chimney sweeps who had been in contact with soot since their early childhood.

In the 1700s and early 1800s, boys (often orphans) as young as four years of age were used as chimney sweeps due to their small size, which allowed them to fit inside chimney flues. During this time in history, most people burned wood in their fireplaces to keep warm. It wasn’t until the early 1800s that coal became the preferred option.

Boys as young as eight years old contracted the disease and many suffered an array of other debilitating illnesses resulting in respiratory and cardiovascular ailments and even blindness. It is believed that dermal absorption, inhalation, and ingestion of soot triggered the diseases. Dioxins were likely the root cause of these diseases.

Startling facts about TCDD dioxin

1 | Diseases which have been linked to dioxin seem endless. Dr. Joe Thornton, Assistant Professor of the Center for Ecology and Evolutionary Biology at the University of Oregon states, “Dioxin’s health effects include endocrine disruption, reproductive impairment, infertility, birth defects, impaired neurological development, damage to the kidneys, and metabolic dysfunction. There is no evidence that there is a safe level of dioxin exposure below which none of these effects will occur.”

2 | The U.S. National Toxicology Program, the International Agency for Research on Cancer of the World Health Organization, and the EPA have determined that TCDD is a proven human carcinogen.

3 | TCDD is on the Special Health Hazard Substance List because it is a teratogen. A teratogen is any agent that causes an abnormality following fetal exposure during pregnancy. Pregnant women and their developing infants are extremely vulnerable to the effects of Dioxin.

4 | TCDD is genotoxic and a well-known mutagen.  A mutagen is a physical or chemical agent that causes a mutation, which is a change in the DNA of a cell. DNA changes caused by mutagens may harm cells and cause certain diseases such as cancer. TCDD alters the genetic structure of living cells. The effect TCDD has on cell structures and genes can be passed down to future generations. In 2012, a scientific study found that dioxin affects not only the health of an exposed rat but also unexposed descendants through a mechanism of epigenetic transgenerational inheritance. Michael Skinner, Ph.D., a professor in the Center for Reproductive Biology at Washington State University, discovered that “exposure to dioxin caused changes in the DNA methylation patterns of sperm that were transmitted across generations to affect the health of multiple generations of descendants. The grandchildren of exposed rats showed dioxin-induced effects ranging from polycystic ovarian disease to kidney disease. Due to its extremely long half-life, dioxin may still affect pregnancies occurring even 20 years after exposure.” The genetic effects of TCDD may skip a generation and reappear in third or subsequent generations.

5 | TCDD is neurotoxic. Neurotoxicity affects the central and/or peripheral nervous system. This may include limb weakness or numbness, loss of memory, vision, and/or intellect, uncontrollable obsessive or compulsive behaviors, delusions, headaches, cognitive problems, and sexual dysfunction.

6 | The International Joint Commission, comprised of the United States and Canadian governments, have publicly stated that zero exposure to dioxin is the only safe level. There is no permissible exposure limit set by the National Institute for Occupational Safety and Health (NIOSH)

7 | TCDD is bio-accumulative and becomes more concentrated with repeated exposure. Once internalized, they accumulate in body tissues resulting in chronic lifetime exposure (Schecter et al., 1994).

8 | Dioxins are so toxic that they are measured in picograms—that is, trillionths (0.000000000001) of a gram. TCDD, even in picograms, is associated with severe health damage that can shorten the lives of people exposed to it.  A picogram of dioxin is the equivalent of a single grain of sand in an Olympic size swimming pool.

9 | No antidote for dioxin toxicity is known.

10 | TCDD was a key ingredient in Agent Orange that was used as a defoliant in the Vietnam War.

11 | Since TCDD is a persistent organic pollutant and can travel long distances in the atmosphere, sunlight, ozone (O3), and hydroxyl (OH) have little effect in oxidizing TCDD or removing it from the air. This indicates that the use of oxidizers in the restoration industry, such as ozone or hydroxyl, would be ineffective to remove TCDD from fire or smoke-damaged structures, soft goods, or textiles.  The only other known way to destroy TCDD is by physically removing the material it has contaminated, or by incinerating it at temperatures over 1550°F.

Safety standards for the fire restoration industry

OSHA states that a hazardous substance is “any biological agent and other disease-causing agent which after release into the environment and upon exposure, ingestion, inhalation, or assimilation into any person…will or may reasonably be anticipated to cause death, disease, behavioral abnormalities, cancer, genetic mutation, physiological malfunctions…or physiological deformations in such persons or their offspring.” It is abundantly clear that TCDD qualifies as a hazardous substance.

Wear protective clothing and equipment

The CDC states this: “All workers who may be exposed to TCDD should be equipped with adequate chemical protective clothing and equipment to ensure their protection. In the selection of protective clothing, consideration should be given to the utilization of disposable apparel due to the uncertainty of decontamination of clothing. The protective apparel should consist of both outer and inner garments. The outer garments should consist of a zippered coverall with attached hood and draw string or elastic sleeves, gloves and closure boots. If exposure is to particulate or dust, the coveralls should be made of a non-woven fabric such as spunbonded polyethylene, Tyvek®. In cases of exposure to liquids, the coveralls, gloves and boots should be made of chemically resistant materials such as disposable laminates, e.g., Saranax® coated Tyvek®, or synthetic elastomers such as butyl, nitrile or neoprene rubber. The inner garments should consist of cotton coveralls, undershirts, undershorts, gloves, and socks and should be disposed of after use. The effectiveness of the protective clothing should be evaluated under simulated use conditions, regardless of the type of clothing used. All disposable clothing should be placed in marked and approved containers and disposed of appropriately. All reusable clothing and equipment should be thoroughly cleaned and checked for residual contamination before reuse or storage.”

There is much to learn about dealing with what we might have thought were routine cleaning and restoration tasks. Stay informed and stay healthy.

Sean Scott has been in the restoration and construction industry for over 42 years and is the Author of Secrets of the Insurance Game and The Red Guide to Recovery – Resource Handbook for Disaster Survivors. He has also written numerous articles and papers on smoke and fire related issues. If you would like more information on estimating fire losses, please feel free to contact him at [email protected] or call 858-453-6767.

Briana Scott is the co-author and editor for Heritage Publishing & Communications. She has been instrumental in providing and interpreting information regarding the ecological effects of disasters, and also adds invaluable knowledge and understanding of scientific processes and her research has been instrumental in raising awareness of a wide range of post-disaster health and environmental hazards.

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