Table 1.

Some key studies from the scientific literature indicating little potential risk from crumb rubber on 3G pitches and playgrounds for most but not all exposed groups and excluding reviews.

Subject	Type of Study/Methods/Size/Strengths and Weaknesses	Reference	Results
Environmental and health assessment of the use of elastomer granulates (virgin and from used tires) as filling in third-generation artificial pitches.	Lab-based using scenarios including looking at one pitch monitored over 11 months period and analysing VOC and metals including impacts on the wider environment and an evaluation of health risks from gas emissions. Total VOC for artificial turf was 8.3 μg/m−3 at 28 days. Relatively small study but one of the few to address risks to workers installing surfaces	[37]	VOCs and formaldehyde were either very or relatively low with levels highest and were not considered a health threat to sports people and spectators from crumb rubber. Largest risk was to workers laying turf over a 5 years period in small and poorly ventilated buildings.
Hydroxypyrene in urine football players after playing on artificial sports field with tire crumb infill.	Studied 7 non-smoking players aged 21 or more exposed for 2.5 h over 3 days period with intensive contact with crumb rubber. Lab-based plus only widely cited human biomonitoring study of crumb rubber chemicals. Very small study in scope, length and partly funded by industry. Controls for doses from other sources that may accumulate with crumb rubber chemicals	[41]	The researchers found no or minimal exposure to certain chemicals from urine samples and within range of uptake from environmental sources and/or diet. The total PAH of the pitch crumb rubber concentration was 24 mg/kg
Crumb-Rubber Infilled Synthetic Turf Athletic Fields. New York.	US study using artificial bio fluids looked at 8 artificial fibres, 8 infills and samples from 7 fields	[40]	Chemical exposures often below detection levels and metals at levels of “low” estimated human risks with the possible exception of lead.
Human Health Risk Assessment of Artificial Turf in Connecticut.	Air sampling from 1 indoor pitch with no active ventilation and 4 outdoor pitches in summer conditions. Testing for chemicals. Small study, limited range and researchers considered benzene levels recorded above background levels could have been due to personal sampling equipment problems. Ingestion potential not part of study	[38]	27 chemicals of concern at above background levels found and possibly field related in all 4 locations but the study concluded none were associated with elevated health risks. Benzothiazole on one pitch recorded at 6.5 μg/m3 on surface.
Artificial turf pitches—an assessment of health risks for football players. Oslo, Norway.	Exposure study based on 3 halls with granulates laid at different times and of different materials. Small study using scenarios of limited range. Study informed later inhalation and oral exposure studies.	[45]	Estimated that health risks were low VOC exposure inhalation Adults = 0.32 m3/kg body wt/day Juniors = 0.16 m3/kg body wt/day
An assessment of health risks for football players and the environment. National Institute of Public Health, Norway	Based on 3 reports. Weaknesses were that data on oral rubber intake were lacking, many VOCs monitored were not classified so health risks were unknown, many VOCs only had acute and not chronic effect classifications. It did note “artificial turf that contains substances of very high concern should not be used”	[36]	Estimated that health risks were low. Children may swallow some rubber granulate (1.0 g) during matches and/or training sessions Worst case inhalation measurements in Manglerudhallen (recycled rubber granulates), 234 different chemicals were found. This gave a total VOC of approximately 716 μg/m3 (indoor house VOC of 200 μg/m3)
Measurement of air pollution in indoor artificial turf halls	Measurements taken in a hall with recently laid rubber granulate (SBR rubber or Styrene Butadiene Rubber), a hall with rubber granulate (SBR rubber) which had been in use for one year and a hall with granulate made from thermoplastic elastomer. Noted gaps in literature on materials, some compounds not identified and some not studied.	[35]	Found low levels of many chemicals but noted “due to the dimensions of a football pitch, inadequate product research before launching a product will lead to a risk of undesirable exposure to chemicals with adverse health effects”
Evaluation of health risks of playing sports on synthetic turf pitches with rubber granulate	Literature review and analysis of rubber granulate from 100 Dutch pitches. 720 samples taken from 6 positions on each pitch. Limited number of migration tests used. Used artificial sweat and assessed migration of chemicals. Developed exposure scenarios for children including goalkeepers and adults. Recognition that the chemical exposures recorded in the study met general European limits for mixtures but would not meet the toy and consumer limit exposure limits. Assumes epidemiological studies reviewed are capable of assessing cancer risk but this is contested.	[55]	“Health risk of playing sports on synthetic turf pitches with an infill of rubber granulate is virtually Negligible”. Maximum pitch concentration found for BaP was 2.2 mg/kg dry matter Noted 2 earlier studies in Europe reported higher concentration of BaP than theirs with maximum values of 8.58 and 11 mg/kg. Low level of toluene, xylene and styrene detected but no benzene.