Competitive U.S. gymnasts can be exposed to high levels of flame retardants through the polyurethane foam padding used in gyms, according to a new study (Environ. Sci. Technol. 2013, DOI: 10.1021/es4037868). Researchers studied 11 college-level gymnasts and found levels of a potentially toxic brominated flame retardant in the athletes’ blood that were almost three times higher than those in the general population.
The study’s lead author, Courtney C. Carignan of Dartmouth College, spent 12 years as a competitive gymnast. Her graduate work at Boston University studying flame retardants and public health alerted her to the idea that the foam in gymnastics training facilities might contain retardants that escape into the gym environment. The athletes use loose foam pits and mesh-covered foam landing mats to protect themselves from injuries when perfecting new moves. The constant battering this equipment endures can produce foam dust.
Gymnasts commonly joke that they “ate pit” after landing, which generally involves being submerged into foam pits, Carignan says, and she remembers at times “coming out of the pit and being covered in this film of pit dust.”
Pentabrominated diphenyl ether (PentaBDE) is a technical mixture of brominated flame retardants that was widely used in polyurethane foam before 2005. That year, U.S. manufacturers voluntarily discontinued the compounds’ use after the European Union had banned them due to increasing evidence of human uptake and potential health effects. Since then, PentaBDE has been banned by the Stockholm Convention on Persistent Organic Pollutants, and studies in animals and people have linked PentaBDE to endocrine disruption, reduced fertility, and neurodevelopmental effects.
However, PentaBDE remains in many long-lived consumer goods containing foam padding made before the phase out. Retardants found in newer gymnastics equipment evaluated in the study included tris(1,3-dichloro-2-propyl) phosphate (TDCPP) and FireMaster 550, which contains tetrabromobenzoate (TBB) and bis(2-ethylhexyl) 2,3,4,5-tetrabromophthalate (TBPH). Some researchers have found that these retardants may also pose health risks (Science 1978, DOI: 10.1126/science.347576; and J. Biochem. Mol. Toxicol. 2013, DOI: 10.1002/jbt.21439).
Carignan and her colleagues began by collecting dust and air samples from two gymnastics training facilities in the eastern U.S. When the team analyzed the samples using gas chromatography coupled with electron capture negative ion mass spectrometry, they found levels of PentaBDE, TBB, and TBPH between one and three orders of magnitude higher than those measured in residences in an earlier study (Environ. Sci. Technol. 2012, DOI: 10.1021/es203314e).
Then the researchers recruited the 11 gymnasts, all of whom had trained for 10 to 19 hours per week for at least a decade, from one of the sampled facilities. The scientists measured the levels of PentaBDE retardants and other persistent organic pollutants (POPs) in the gymnasts’ blood. The athletes’ serum concentrations of all of the POPs except the PentaBDEs were lower than those in the general population, establishing gyms as the source of the elevated PentaBDE levels.
The gymnasts’ levels of one component of PentaBDE, called BDE-153, were especially high. The geometric mean concentrations were four to 6.5 times higher than levels in the general population, concentrations similar to levels found in carpet installers and foam recyclers, two groups that regularly come in contact with flame-retarded products (Environ. Sci. Technol. 2008, DOI: 10.1021/es7028813). Coauthor Thomas F. Webster of Boston University’s School of Public Health points out that BDE-153 has a six- to 12-year half-life in the body, so some of the retardants measured in the gymnasts’ blood probably resulted from exposures at other gyms.
The gymnasts might have inhaled or ingested the flame retardants, though the exact exposure route is unclear, the researchers say. The fat-soluble flame retardants can also stick to skin. Samples collected from the gymnasts’ hands had two to three times higher concentrations of PentaBDE, TBB, and TBPH after practice than before.
Linda S. Birnbaum, director of the National Institute of Environmental Health Sciences, applauds the team for their careful and thorough work in relating the elevated levels of flame retardants in the gym air and dust with those in the athletes’ blood.
Although the types of flame retardants used in foam vary depending on locale, the widespread use of flame retardants suggests “a strong likelihood that elite gymnasts worldwide will suffer elevated exposures to chemicals present in polyurethane foam used in gymnasiums,” says Stuart J. Harrad of the University of Birmingham, in the U.K. This is concerning because many aspiring gymnasts are pubescent, a time when they may be particularly vulnerable to chemical exposures, points out Miriam L. Diamond of the University of Toronto.
Carignan has created a website to help concerned gymnasts and gym owners share information on how to minimize exposure. Previous work by Webster’s group has demonstrated that hand-washing can reduce flame retardant exposure (Environ. Health Perspect. 2011, DOI: 10.1289/ehp.1003271), and Carignan hopes to follow up by evaluating the method’s effectiveness for gymnasts.