by Robert Wright and Sarah Evans
Given the hazards associated with recycled tire rubber, these products should never be used as surfaces where children play. We should all be concerned that there are significant gaps in the evidence supporting the safety of recycled rubber turf products. We raise concerns as pediatricians, epidemiologists, and laboratory scientists at the Children’s Environmental Health Center of the Icahn School of Medicine at Mount Sinai, which hosts one of 10 nationally funded Pediatric Environmental Health Specialty Units.
Children are uniquely vulnerable to harmful exposures from recycled rubber surfaces. Public playgrounds are typically utilized by children age 6 months to 12 years, a population exquisitely vulnerable to the health effects of toxic environmental exposures. This vulnerability is due to a number of factors including, but not limited to, their unique physiology and behaviors, rapidly developing organ systems, and immature detoxification mechanisms. Additionally, because of their young age, children have more future years of life and therefore more time to develop chronic diseases.
Concerns about the safety of recycled rubber playing surfaces have been raised by the federal government, based on the lack of comprehensive studies.
On February 12, 2016, the United States Environmental Protection Agency (USEPA) announced the launch of an investigation into the safety of crumb rubber in partnership with the Centers for Disease Control and Prevention and the Consumer Product Safety Commission, stating “existing studies do not comprehensively evaluate the concerns about health risks from exposure to tire crumb”.
In December of 2016, USEPA published a status report describing the activities to date related to this investigation. Although research findings are not yet available, the report describes the completed review of the scientific literature related to recycled rubber playing surfaces, noting that data gaps were more pronounced for playground surfaces than for athletic fields. Of 88 reviewed studies, only 8 were related to playground surfaces.
According to the report, the limited scientific literature concludes that “additional studies are needed to support the safety of recycled tire rubber in playground surfaces”. Importantly, no studies have addressed children’s exposure to chemicals from recycled rubber playground surfaces via oral, inhalational, and dermal routes. To address identified gaps, CPSC plans to conduct field observation studies, focus groups, a national survey of caregivers, and exposure modeling based on recycled rubber composition and bioavailability data currently being collected by USEPA and ATSDR.
Until the findings of these studies are available and conclusively demonstrate the safety of recycled rubber playground surfaces, we recommend a ban on the use of these materials where children play. We have identified several potential dangers that playing on recycled rubber playing surfaces pose to children, including:
- Extreme heat. On hot summer days, temperatures of over 160 degrees Fahrenheit have been recorded on recycled rubber play surfaces. Vigorous play in these conditions conveys a very real risk of burns, dehydration, heat stress, or heat stroke. Children are less able to regulate their body temperature than adults, making them particularly susceptible to conditions of extreme heat. In addition, children have a higher surface area to body mass ratio, produce more body heat per unit mass, and sweat less than adults, all factors that increase susceptibility to heat injury.
- Inhalation and ingestion of toxic and carcinogenic chemicals. Children are particularly vulnerable to chemical exposures from playground surfaces due to their developmentally appropriate hand to mouth behaviors. In addition, their close proximity to the ground and higher respiratory rates compared with adults increase the likelihood of inhalational exposures. Thus, there is a potential for toxins to be inhaled, absorbed through the skin and even swallowed by children who play on recycled rubber surfaces. The major chemical components of recycled rubber are styrene and butadiene, the principal ingredients of the synthetic rubber used for tires in the United States. Styrene is neurotoxic and reasonably anticipated to be a human carcinogen. Butadiene is a proven human carcinogen that has been shown to cause leukemia and lymphoma. Shredded and crumb rubber also contain lead, cadmium, and other metals known to damage the developing nervous system,. Some of these metals are included in tires during manufacture, and others picked up by tires as they roll down the nation’s streets and highways. It is important to note that risk of harm due to exposures from recycled rubber turf has been assessed only for single chemicals, yet children are exposed to numerous harmful chemicals in aggregate during play on these surfaces.
- Transportation home of rubber pellets. Recycled rubber materials used in play surfaces break down into smaller pieces over time that may be picked up on children’s shoes, clothing and skin. The rubber is then tracked into children’s homes and cars, and carried into the places where children live, play, eat and sleep. Thus exposure can continue for many hours beyond the time that a child spends in the play area.
- Escape of chemical hazards from rubber surfaces to the environment. A number of the toxic and chemical components of the recycled rubber that is installed on playgrounds are soluble in water. When rain and snow fall on synthetic fields, these materials can leach from the surface to contaminate ground water and soil. In addition, chemicals in turf can be released into the air and inhaled, particularly on hot days.
Safe alternatives to recycled rubber playground surfaces exist. Daily outdoor play and physical activity are essential components of a healthy childhood. Thus safe play areas are critical to any school environment. Our priority should be ensuring that the health risks do not outweigh the rewards.
Robert Wright, MD, MPH is Director, and Sarah Evans, PhD, MPH, is a faculty member of the Children’s Environmental Health Center, Icahn School of Medicine at Mount Sinai, in New York City. This article is based on testimony provided to the Connecticut General Assembly’s Committee on Children during the current legislative session regarding HB 6998, An Act Concerning the Use of Recycled Tire Rubber at Municipal and Public School Playgrounds. Artificial Turf: A Health-Based Consumer Guide was published this month.
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