Researching Risk of Birth Defects Among Children of Male Firefighters

Over 1.1 million firefighters protect our communities and environment in the United States.¹ Firefighters face hazardous conditions and chemicals while on the job, which may have safety and health implications. The National Fallen Firefighters Foundation named reproductive health as a priority research topic in 2021. But so far very few studies have evaluated birth defects among the children of firefighters. This may be in part because of the difficulty of studying these rare conditions.

Researchers from the National Institute for Occupational Safety and Health and collaborators from the Centers for Disease Control and Prevention, University of North Carolina at Chapel Hill, and the National Development and Research Institutes’ Center for Fire, Rescue, and EMS Health Research used the National Birth Defects Prevention Study (NBDPS) to analyze birth defects among children of male firefighters. NBDPS is a large study of birth defects that included mothers and their infants born from 1997-2011. During a telephone interview, women provided information about their jobs and jobs held by their babies’ fathers throughout pregnancy. We compared cases of birth defects among infants who have firefighter fathers to:

1. Those who have fathers in non-firefighter jobs
2. Those who have fathers in police officer jobs

Like firefighters, police officers are emergency responders, and they share many characteristics with firefighters. However, one key difference between the nature of their work is that police officers are likely not exposed to fire-related hazards (such as heat and chemicals) as often or as intensely as firefighters. Therefore, we compared police officers to firefighters so we could explore associations that are more directly related to those hazards.

The study population included 227 infants whose fathers were firefighters, 433 whose fathers were police officers, and 35,852 whose fathers had other occupations. We analyzed 29 birth defect groups. The results were recently published in The American Journal of Industrial Medicine.²

What we learned about birth defects among children of male firefighters

Our results suggest that infants born with total anomalous pulmonary venous return (TAPVR), a congenital heart defect, were roughly three times more likely to have a firefighter versus non-firefighter father compared with infants who did not have a birth defect. TAPVR is a condition which affects the heart’s ability to pump oxygen-rich blood back out to the body. Babies born with this condition may need surgery or other procedures soon after they are born. Additionally, infants born with a limb defect called transverse limb deficiency were roughly two times more likely to have a firefighter versus non-firefighter father compared to infants who did not have birth defects. Limb deficiencies occur when part or all of an arm or leg does not form completely. Children born with limb deficiencies may face problems such as difficulties with motor skills or limitations with certain movements or activities. Similarly, infants born with cleft palate or cleft lip were about two times more likely to have a firefighter versus non-firefighter father compared to infants who did not have birth defects. We also found that infants born with cleft palate were over two times more likely to have a firefighter versus police officer father compared to infants who did not have birth defects. Cleft palate or lip happens when the tissue making up the upper lip or roof of the mouth does not join completely during pregnancy. This can cause problems such as difficulties with feeding and speaking.

What we still don’t know

Further research could help confirm these findings and clarify how firefighting affects firefighters’ children. Workplace exposures among firefighters, such as from heat and chemicals, could impact birth outcomes in children by, for example, altering developing sperm. Exposures could also impact birth outcomes through take-home exposures affecting a firefighter’s pregnant co-parent. In other words, chemicals on firefighters’ skin or clothes could end up being ingested or inhaled by people they encounter outside work.^3,4 Future studies could look into specific chemical, take-home, heat, or other types of exposures that might be associated with birth defects among children of male firefighters. These studies would be helpful because researching what might cause these findings could give clues about what we can do to improve firefighters’ reproductive health.

To our knowledge, this research included the largest number of children with birth defects born to firefighters to-date. Still, birth defects are rare. Roughly a third of defects we analyzed had less than five cases born to firefighter fathers. It is important to note that because there are so few cases of birth defects, our estimates of the relationship between these defects and paternal firefighting occupation are less certain than if we were studying a more common condition. The comparison with police officer fathers had even fewer cases.

Despite these challenges, this work addresses a difficult-to-study area of research and a topic of great concern to the fire service. National fire service organizations recognize the need for clear evidence-based information on how firefighting impacts reproductive health and guidance for how to reduce potential reproductive hazards.

What firefighters can do to protect themselves

Post-fire cleanup, such as changing clothes, wiping off skin, and showering as soon as possible following fire response, can reduce chemical exposure for firefighters.

Research related to firefighters’ exposures and cancer risk has grown over the past decade. As a result, awareness levels, workplace practices and policies, and healthy behaviors among firefighters are also increasing. This cultural shift, while primarily aimed at preventing cancer and other chronic diseases, may also protect reproductive health among firefighters and their families.

Fire service members, leadership, and organizations can continue to promote decontamination practices and work toward reducing exposure among firefighters.⁵ Continued research attention may also help us better understand the reproductive health of male and female firefighters and their families and can guide policy decisions and standard operating guidelines.

Amel Omari, PhD, MPH, is an occupational epidemiologist in the NIOSH Division of Field Studies and Engineering.

Miriam R. Siegel, DrPH, MPH, is an occupational epidemiologist in the NIOSH Division of Field Studies and Engineering.

Carissa M Rocheleau, PhD, is a reproductive occupational epidemiologist in the NIOSH Division of Field Studies and Engineering.

For more information and resources on workplace safety for firefighters see:

Take-home Exposures – Reproductive Health

Firefighter Resources

Links to external sites are for informational purposes only and do not constitute endorsement by the National Institute for Occupational Safety and Health, the Centers for Disease Control and Prevention, or the U.S. Department of Health and Human Services.

References

1. Evarts B, Stein GP. US Fire Department Profile 2018. 2020. https://www.nfpa.org/-/media/Files/News-and-Research/Fire-statistics-and-reports/Emergency-responders/osfdprofile.pdf
2. Siegel MR, Rocheleau CM, Hollerbach BS, et al. Birth defects associated with paternal firefighting in the National Birth Defects Prevention Study. Am J Ind Med. 2022:1-11. doi:10.1002/ajim.23441
3. Burdorf A, Figà-Talamanca I, Jensen TK, Thulstrup AM. Effects of occupational exposure on the reproductive system: core evidence and practical implications. Occup Med (Lond). Dec 2006;56(8):516-20. doi:10.1093/occmed/kql113
4. Jensen TK, Bonde JP, Joffe M. The influence of occupational exposure on male reproductive function. Occup Med (Lond). Dec 2006;56(8):544-53. doi:10.1093/occmed/kql116
5. Horn GP, Fent KW, Kerber S, Smith DL. Hierarchy of contamination control in the fire service: Review of exposure control options to reduce cancer risk. J Occup Environ Med. 2022;19(9):538-557. doi:10.1080/15459624.2022.2100406.