Table 6-6. Field-Specifica One-Day Multi-Route Hazard Index for DARTs Receptor
Category Age Group One-Day HIDART
Mean Maximum
Athletes 2<6 years <0.01 <0.01
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Receptor
Category Age Group One-Day HIDART
Mean Maximum
6<11 years <0.01 <0.01
11<16 years 0.39 1.30
16<30 years 0.58 1.80
30<40 years 0.39 1.20
40<50 years 0.39 1.20
50<70 years 0.42 1.30
Coaches
16<30 years 0.25 0.78
30<40 years 0.21 0.68
40<50 years 0.22 0.69
50<70 years 0.22 0.69
Referees
16<30 years 0.23 0.73
30<40 years 0.20 0.64
40<50 years 0.20 0.64
50<70 years 0.20 0.64
Spectators
on-Field
0<2 years <0.01 <0.01
11<16 years 0.07 0.23
16<30 years 0.05 0.15
30<40 years 0.04 0.13
40<50 years 0.04 0.14
50<70 years 0.04 0.14
Spectators
off-Field
11<16 years 0.08 0.45
16<30 years 0.05 0.30
30<40 years 0.05 0.26
40<50 years 0.05 0.26
50<70 years 0.05 0.26 a 35 field-specific One-Day HIDART are included in this table.
6.4. Noncancer Hazards: Sensory Irritation
Three chemicals, one field related and two non-field related, were evaluated as sensory irritants (Table 6-7). Each individual field hazard was assessed using each field’s average concentrations for sensory irritants (Chronic Cinh-sensory-field, Appendix Section F.4.5) and Sensory TCinh (Section 4.4.2). The mean and maximal hazard quotients, not specific to receptor or age categories, were less than 0.01 for on-field exposures (Table 6-8). The off-field HIsensory-field were all less than 0.01 and are not shown in the table.
Overall, the only field-related chemical, styrene, evaluated as a sensory irritant did not present a hazard on- or off-field. The non-field-related chemicals presented a small concern on-field (no non-field-related sensory irritants were detected off-field) at the maximal calculated HIsensory-field, as seen in Table 6-8 and Appendix Table G-52, driven 4-258
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by formaldehyde.
Table 6-7. Sensory Irritant Chemicals Evaluated for Inhalation Chronic Hazard Field-Related
Chemicals
Non-Field-Related
Chemicals
Styrene Acetaldehyde
Formaldehyde
Table 6-8. Field-Specifica Hazard Index for Inhalation Exposure to Sensory Irritants (HIsensory-field) for All Ages and Receptor Groups
Chemical Group HI
Mean
HI
Maximum
Field-related Sensory Irritants, On-field <0.01 <0.01
Non-Field related Sensory Irritants, On-field 0.44 1.90 All Sensory Irritants, On-field 0.44 1.90
a 35 field-specific HIsensory-field are included in this table.
6.5. Noncancer Hazards: Chronic Effects
This section presents the results of HQ and HI calculated for general chronic toxicity, for multiple routes of exposure (inhalation, dermal, and ingestion) on or off the synthetic turf fields.
6.5.1. Inhalation Exposure
Ninety-four volatile and semi-volatile chemicals were analyzed from on- and off-field sampling. Seventy-three were considered field-related and 21 were considered nonfield-related chemicals for inhalation exposure (Table 6-9). Chapter Section 4.4.4 lists the toxicity criteria, Chronic TCinh, for these chemicals. To assess hazards associated with chronic inhalation of these general chemicals, the average concentration for those chemicals detected on an individual field, for on- or off-field, was used to calculate the individual field exposure concentration, Cinh-field. These exposure concentrations are in Appendix Section F.4.6.
Table 6-9. General Chemicals Evaluated for Chronic Hazard Chemical Route Evaluated
Inhalation Dermal Ingestion
Field-Related Chemicals
Acenaphthylene X X X
Acetone X
Aluminum X
Aniline X X X
Anthracene X X X
Anthracene, 2-methyl- X X X
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Chemical Route Evaluated
Inhalation Dermal Ingestion
Anthracene, 9,10-dimethyl X X
Anthracene, 9-phenyl X X X
Anthracene, 9,10-diphenyl- X X
Antimony X
Barium X
Benz[a]anthracene X X X
Benzaldehyde X
Benzene, n-butyl- X X X
1,4-Benzenediamine, N-(1,3-dimethylbutyl)-
N'-phenyl- X X X
Benzene, 1,2,3-trimethyl- X
Benzene, 1,2,4,5-tetramethyl- X
Benzene, 1,2,4-trimethyl- X
Benzene, 1-ethyl-2,4-dimethyl- X
Benzene, 2-ethyl-1,4-dimethyl- X
Benzo[b]fluoranthene X X X
7H-Benzo[c]fluorene X X X
Benzo[k]fluoranthene X X X
Benzothiazole X X X
Benzothiazole, 2-phenyl- X X X
1,3-Benzothiazole-2-thiol X
2-Benzothiazolone X X X
Benzyl butyl phthalate X X X
Beryllium X
Butanal X
Butylated Hydroxytoluene X
Cadmium X
Chromium X
Cobalt X
Copper X
Cyclohexyl isothiocyanate X X
Cyclopentasiloxane, decamethyl- X
Cyclotetrasiloxane, octamethyl- X
p-Cymene X
Decane X
Dibenz[a,h]anthracene X X X
Dibenzothiophene X X X
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Chemical Route Evaluated
Inhalation Dermal Ingestion
Dibutyl phthalate X X
Diethyl phthalate X X X
Diisobutyl phthalate X X X
Diisooctylphthalate X X X
Di-n-octyl phthalate X X X
2,5-di-tert-Butyl-1,4-benzoquinone X X X
3,5-di-tert-Butyl-4-hydroxybenzaldehyde X X X
Dodecane X
Fluoranthene X X X
Fluorene X X X
Furan, 2-methyl X
Heptanal X
Hexadecane X X
2,5-Hexanedione X
1-Hydroxypyrene X X
Hexanoic Acid, 2-ethyl X
Indan X
Lead X
Manganese X
Mesitylene X
Methacrolein X
Methyl Isobutyl Ketone X
2-(Methylthio)benzothiazole X X
Molybdenum X
Naphthalene X X X
Naphthalene, 2-(bromomethyl)- X X X
Naphthalene, 1,2-dimethyl- X X X
Naphthalene, 1,6-dimethyl- X X X
Naphthalene, 2,3-dimethyl- X X X
Naphthalene, 1-methyl- X X X
Naphthalene, 2-methyl- X X X
1-Octadecene X X X
Octanal X
Octane X
17-Pentatriacontene X X
Phenanthrene X X X
Phenanthrene, 1-methyl X X X
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Chemical Route Evaluated
Inhalation Dermal Ingestion
Phenanthrene, 2-methyl- X X X
Phenanthrene, 3-methyl X X X
N-Phenylbenzamide X X X
Phthalimide X X
Propionaldehyde X
Pyrene X X X
Pyridine, 2-(4-methylphenyl)- X X X
Resorcinol X
Selenium X
Strontium X
Thallium X
Tin X
m-Tolualdehyde X
Triethylene glycol monobutyl ether X X
TXIB "Kodaflex" X
5,9-Undecadien-2-one, 6,10-dimethyl- X X X
Undecane X
Valeraldehyde X
Vanadium X
Zinc X
Non-Field-Related Chemicals
Benzene X
Benzene, 1,4-dichloro X
Benzene, 1-chloro-4-(trifluoromethyl)- X
2-Butoxyethanol X
Cyclotrisiloxane, hexamethyl- X
Decanal X
Ethylbenzene X
Heptane X
Hexanal X
Hexane X
1-Hexanol, 2-ethyl- X
Nonanal X
Phenol X
Tetrachloroethylene X
Tetradecane X
Texanol, TXIB (mono-isomer) X
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Chemical Route Evaluated
Inhalation Dermal Ingestion
Toluene X
Trichloroethylene X
Trichloromethane X
m/p-Xylene X
o-Xylene X
For the inhalation route, the on-field HQinh-sum-field for all general (field and non-field) chemicals were below 1.0 for every receptor category and age group, as can be seen in Table 6-10. Nearly the same results were obtained for the off-field chronic exposures as well. Thus, chronic inhalation exposure to chemicals from crumb rubber infill does not present a significant hazard to participants and spectators. All the HQ values for chronic health hazards associated with general chemicals are presented in Appendix Section G.2.4.
Table 6-10. Field-Specifica Chronic Inhalation Route Total Hazard Quotients for All General Chemicals
Receptor
Category Age Group
Field-Related
General Chemicals
Non-Field-Related
General Chemicals
All General
Chemicals
Chronic HQinh-sum-field Chronic HQinh-sum-field Chronic HQinh-sum-field Mean Maximum Mean Maximum Mean Maximum
Athletes
2<6 years 0.1 0.23 0.06 0.21 0.15 0.37
6<11 years 0.13 0.30 0.07 0.28 0.2 0.48
11<16 years 0.12 0.30 0.07 0.27 0.19 0.47
16<30 years 0.23 0.56 0.13 0.51 0.36 0.88
30<40 years 0.15 0.37 0.09 0.33 0.24 0.58
40<50 years 0.15 0.36 0.09 0.33 0.23 0.57
50<70 years 0.15 0.35 0.08 0.32 0.23 0.56
Coaches
16<30 years 0.10 0.23 0.05 0.21 0.15 0.36
30<40 years 0.08 0.2 0.05 0.18 0.13 0.32
40<50 years 0.08 0.2 0.05 0.19 0.13 0.32
50<70 years 0.08 0.2 0.05 0.19 0.13 0.32
Referees
16<30 years 0.04 0.09 0.02 0.08 0.06 0.14
30<40 years 0.03 0.08 0.02 0.07 0.05 0.12
40<50 years 0.03 0.08 0.02 0.07 0.05 0.12
50<70 years 0.03 0.08 0.02 0.07 0.05 0.12
Spectators
On-field
Third
trimester
fetus
0.01 0.03 <0.01 0.03 0.02 0.05
0<2 years 0.10 0.25 0.06 0.23 0.16 0.39
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Receptor
Category Age Group
Field-Related
General Chemicals
Non-Field-Related
General Chemicals
All General
Chemicals
Chronic HQinh-sum-field Chronic HQinh-sum-field Chronic HQinh-sum-field Mean Maximum Mean Maximum Mean Maximum
2<6 years 0.05 0.13 0.03 0.12 0.09 0.21
6<11 years 0.05 0.13 0.03 0.11 0.08 0.2
11<16 years 0.02 0.05 0.01 0.05 0.04 0.09
16<30 years 0.02 0.04 <0.01 0.03 0.02 0.06
30<40 years 0.01 0.03 <0.01 0.03 0.02 0.05
40<50 years 0.01 0.03 <0.01 0.03 0.02 0.05
50<70 years 0.01 0.03 <0.01 0.03 0.02 0.05
Spectators
Off-field
Third
trimester
fetus
<0.01 0.03 <0.01 0.04 0.01 0.06
0<2 years 0.04 0.20 0.07 0.29 0.11 0.45
2<6 years 0.02 0.10 0.04 0.15 0.06 0.23
6<11 years 0.02 0.10 0.03 0.15 0.05 0.22
11<16 years <0.01 0.04 0.01 0.06 0.02 0.10
16<30 years <0.01 0.03 <0.01 0.04 0.02 0.06
30<40 years <0.01 0.03 <0.01 0.04 0.01 0.06
40<50 years <0.01 0.03 <0.01 0.04 0.01 0.06
50<70 years <0.01 0.03 <0.01 0.04 0.01 0.06 a 35 field-specific Chronic HQinh-sum-field are included in this table.
6.5.2. Dermal and Ingestion Exposures
Forty-nine general chemicals were evaluated for chronic dermal on-field exposure and 69 general chemicals were evaluated for chronic ingestion on-field exposure. Dermal and ingestion exposures for off-field exposures to general chemicals were not evaluated as crumb rubber were not present off the fields. The chemicals evaluated are listed in Table 6-9. Chapter Sections 4.5.2 for organic chemicals and 4.6.2 for metals and metalloids list the toxicity criteria for these chemicals. The average daily dose of a general chemical via the dermal and ingestion exposure routes (ADDder and ADDing, respectively) are shown in Appendix Sections F.5.3 and F.5.6.
The HQder-sum-field was calculated by summing the HQder-field for each chemical within the specific category and age group. Similar summations were made to calculate HQing-sumfield from HQing-field. There was no receptor category and age group that had a HQder-sumfield greater than 0.01.
Only the age groups within the receptor categories of athletes and spectators had HQingsum-field considerably above 0.01, with the largest at 1.00 as the maximum calculated value for the spectator category age group 0<2 years, as can be seen in Table 6-11. All 4-264
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HQder, HQder-sum-field, HQing, and HQing-sum-field can be found in Appendix Sections G.2.6 for dermal exposure and G.2.8 for ingestion exposure. Overall, the calculated HQs were below 1 for chronic dermal and ingestion exposures to the general chemicals in all participant and spectator groups.
Table 6-11. On-Field Field-Specifica Chronic Ingestion Route Total Hazard Quotients for All General Chemicals
Receptor
Category Age Group Chronic HQing-sum-field
Mean Maximum
Athletes
2<6 years 0.10 0.28
6<11 years 0.06 0.19
11<16 years 0.05 0.15
16<30 years 0.06 0.16
30<40 years 0.04 0.11
40<50 years 0.03 0.09
50<70 years 0.03 0.10
Coaches
16<30 years 0.01 0.04
30<40 years 0.01 0.04
40<50 years 0.01 0.04
50<70 years 0.01 0.04
Referees
16<30 years <0.01 0.02
30<40 years <0.01 0.02
40<50 years <0.01 0.02
50<70 years <0.01 0.02
Spectators
Third trimester
fetus <0.01 0.01
0<2 years 0.34 1.00
2<6 years 0.16 0.47
6<11 years 0.11 0.33
11<16 years <0.01 0.03
16<30 years <0.01 0.02
30<40 years <0.01 0.01
40<50 years <0.01 0.01
50<70 years <0.01 0.01 a 35 field-specific Chronic HQing-sum-field are included in this table.
6.5.3. Hazard Index
The hazard indices based on all routes of exposure to all general chemicals are presented in Table 6-12. The mean chronic HIfields for all receptor categories and age groups are below 1 from exposure to field-related, non-field-related and combined chemicals. The maximum individual field chronic HIfield calculated for the 16<30 year old 4-265
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athletes group was at 1. The primary reason for this finding comes from the higher maximum chronic HQinh-sum-fields for both field-related and non-field-related inhalation exposures for this group seen in Table 6-10. While the HQinh-sum-fields are not above 1, they contribute the most to the final HIfield. The primary contributors were the fieldrelated chemical 2-methyl furan and the non-field-related chemicals benzene and hexanal. The maximum individual field chronic HIfield calculated for the 0<2 year old spectator group was slightly above 1 for field-related chemical exposure, and this is a consequence of the HQing-sum-field (=1) for this age group for the ingestion route as seen in Table 6-11, driven by lead. Hand to mouth activity of infants would explain the higher ingestion of crumb rubber from the fields.
Figure 6-1 shows the distribution of HI for field-related chemicals and all chemicals for the 35 individual fields for both the athletes 16<30 years age group and the spectator 0<2 years age group. The off-field chronic HIfields are not shown since they are the same as the chronic HQinh-sum-field in Table 6-10. All on-field and off-field chronic HIfield values are presented in Appendix Section G.2.10.
Table 6-12. On-Field Field-Specifica Chronic Hazard Index (Chronic HIfield, unitless) for General Chemicalsb—Combined Gender
Receptor
Category Age Group
On-Field Chronic HIfield
Field-Related
General Chemicals
Non-Field-Related
General Chemicals
All General
Chemicals
Mean Maximum Mean Maximum Mean Maximum
Athletes
2<6 years 0.20 0.41 0.06 0.21 0.25 0.59
6<11 years 0.19 0.42 0.07 0.28 0.26 0.62
11<16 years 0.17 0.39 0.07 0.27 0.24 0.58
16<30 years 0.29 0.66 0.13 0.51 0.42 1.00
30<40 years 0.19 0.43 0.09 0.33 0.28 0.66
40<50 years 0.18 0.42 0.09 0.33 0.27 0.64
50<70 years 0.18 0.41 0.08 0.32 0.26 0.63
Coaches
16<30 years 0.11 0.26 0.05 0.21 0.16 0.40
30<40 years 0.10 0.23 0.05 0.18 0.14 0.35
40<50 years 0.10 0.23 0.05 0.19 0.15 0.35
50<70 years 0.10 0.23 0.05 0.19 0.15 0.35
Referees
16<30 years 0.04 0.10 0.02 0.08 0.06 0.15
30<40 years 0.04 0.09 0.02 0.07 0.06 0.13
40<50 years 0.04 0.09 0.02 0.07 0.06 0.13
50<70 years 0.04 0.09 0.02 0.07 0.06 0.13
Spectators
On-Field
Third
trimester
fetus
0.02 0.04 <0.01 0.03 0.03 0.06
0<2 years 0.44 1.10 0.06 0.23 0.50 1.20
2<6 years 0.22 0.54 0.03 0.12 0.25 0.58
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Receptor
Category Age Group
On-Field Chronic HIfield
Field-Related
General Chemicals
Non-Field-Related
General Chemicals
All General
Chemicals
Mean Maximum Mean Maximum Mean Maximum
6<11 years 0.17 0.39 0.03 0.11 0.20 0.45
11<16 years 0.03 0.07 0.01 0.05 0.05 0.11
16<30 years 0.02 0.05 <0.01 0.03 0.03 0.07
30<40 years 0.02 0.04 <0.01 0.03 0.03 0.06
40<50 years 0.02 0.04 <0.01 0.03 0.03 0.06
50<70 years 0.02 0.04 <0.01 0.03 0.03 0.06 a 35 field-specific Chronic HIfield are included in this table. b Lead is included in Chronic HIfield calculation (see Section G.2.2 for details). c Lifetime Average Chronic HI is the 70 year weighted lifetime average of all age groups within a receptor category.
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Figure 6-1. Chronic Hazard Index for Field-Related Versus All Chemicals. Top panel is for the Athlete 16<30 years group and the bottom panel is for the Spectator 0<2 years group.
6.6. Cancer Risk
6.6.1. Inhalation Exposure
OEHHA evaluated the cancer risk from inhalation exposure to 19 carcinogens listed in Table 6-13. Of these, 12 carcinogens were field-related, and 7 carcinogens were nonfield-related. The age-sensitivity-weighted lifetime average daily dose and the cancer slope factors for evaluating inhalation cancer risk from exposure to these chemicals are presented in Section F.6.1 and Section 4.4.5, respectively.
Table 6-14 shows the cancer risks for all field-related and non-field-related carcinogens from exposure on-field for all receptor categories as well as off-field for the Spectator category. All inhalation cancer risks can be found in Appendix Section G.3.1.
Table 6-13. Chemicals Evaluated for Cancer Risk
Chemical Route Evaluated
Inhalation Dermal Ingestion
Field-Related Chemicals
Aniline X X X
Arsenic X
Benz[a]anthracene X X X
Benzo[a]pyrene X X X
Benzo[b]fluoranthene X X X
Benzo[k]fluoranthene X X X
1,3-Benzothiazole-2-thiol X
Chromium X
Chrysene X X X
Cyclopenta[cd]pyrene X X X
Dibenz[a,h]anthracene X X X
Indeno[1,2,3-cd]pyrene X X X
Lead X
Methyl Isobutyl Ketone X
Naphthalene X X X
Styrene X
Non-Field-Related Chemicals
Acetaldehyde X
Benzene X
Benzene, 1,4-dichloro X
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Benzene, 1-chloro-4-(trifluoromethyl)- X
Ethylbenzene X
Formaldehyde X
Tetrachloroethylene X
Each individual field risk was assessed using the age-sensitivity-weighted lifetime average daily dose, LADD (Appendix Section F.6) and CSF (CSFinh: Section 4.4.5 and CSForal: Sections 4.5.3 and 4.6.3).
The mean of the sum of cancer risk associated with field-related chemicals was below 1 in a million for all receptor categories. The maximum risk value calculated for the 35 fields ranged up to 1 in a million for athletes while it was below 1 in a million for the other four receptor categories. The mean cancer risk associated with the non-fieldrelated chemicals ranged from 0.02 to 3.7 in a million, with the maximal values ranging from 0.07 to 11 in a million, and it accounted for, in general, 90% or more of the total cancer risks on all fields (Table 6-14).
Table 6-14. Field-Specifica
Inhalation Cancer Risk (Riskinh-sum-field)
Receptor
Category Age Group
Riskinh-sum-field x 10-6
Average of Individual Fields Range of Individual Fields Field-Related Non-FieldRelated Field-Related Non-FieldRelated Athletes
2<6 years 0.08 1.3 0.0004 – 0.4 0.3 – 3.9
6<11 years 0.1 2.2 0.0007 – 0.6 0.5 – 6.4
11<16 years 0.1 2.1 0.0006 – 0.6 0.5 – 6.2
16<30 years 0.2 3.7 0.001 -1.0 0.9 – 11.0
30<40 years 0.1 1.7 0.0005 – 0.5 0.4 – 5.1
40<50 years 0.10 1.7 0.0005 – 0.5 0.4 – 5.0
50<70 years 0.2 3.4 0.001 – 0.9 0.8 – 9.9
Coaches
16<30 years 0.09 1.5 0.0005 – 0.4 0.4 – 4.5
30<40 years 0.05 1.0 0.0003 – 0.3 0.2 – 2.8
40<50 years 0.05 1.0 0.0003 – 0.3 0.2 – 2.9
50<70 years 0.1 1.9 0.0006 – 0.5 0.4 - -5.7
Referees
16<30 years 0.03 0.6 0.0002 – 0.2 0.1 – 1.7
30<40 years 0.02 0.4 0.0001 – 0.09 0.08 – 1.0
40<50 years 0.02 0.4 0.0001 – 0.1 0.08 – 1.1
50<70 years 0.04 0.7 0.0002 – 0.2 0.2 – 2.1
On-Field
Spectators
Third trimester
fetus 0.002 0.04 0.00001 – 0.01 0.008 – 0.1
0<2 years 0.1 2.4 0.0007 – 0.6 0.5 -7.0
2<6 years 0.04 0.7 0.0002 – 0.2 0.2 – 2.2
6<11 years 0.05 0.9 0.0003 – 0.2 0.2 – 2.6
11<16 years 0.02 0.4 0.0001 – 0.1 0.09 – 1.1
16<30 years 0.01 0.2 0.00007 – 0.06 0.05 – 0.7
30<40 years 0.008 0.1 0.00004 – 0.04 0.03 – 0.4
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Receptor
Category Age Group
Riskinh-sum-field x 10-6
Average of Individual Fields Range of Individual Fields Field-Related Non-FieldRelated Field-Related Non-FieldRelated 40<50 years 0.008 0.1 0.00005 – 0.04 0.03 – 0.4
50<70 years 0.02 0.3 0.0001 – 0.08 0.07 – 0.9
Off-Field
Spectators
Third trimester
fetus 0.002 0.02 0 - 0.01 0.004 – 0.07
0<2 years 0.1 1.1 0 - 0.7 0.3 – 4.7
2<6 years 0.04 0.4 0 - 0.2 0.08 – 1.5
6<11 years 0.1 0.4 0 - 0.3 0.1 – 1.8
11<16 years 0.02 0.2 0 - 0.1 0.04 – 0.8
16<30 years 0.01 0.1 0 - 0.1 0.03 – 0.5
30<40 years 0.01 0.07 0 - 0.04 0.02 – 0.3
40<50 years 0.01 0.07 0 - 0.04 0.02 – 0.3
50<70 years 0.02 0.1 0 - 0.1 0.03 – 0.6
a The mean and maximum values in the table are based on 35 field-specific Riskinh-sum-field.
6.6.2. Dermal and Oral Exposures
Calculations of incremental lifetime cancer risk resulting from the field-related chemicals were conducted for dermal and oral routes. There were 11 carcinogenic chemicals evaluated for dermal exposure and 13 carcinogenic chemicals evaluated for exposure through ingestion of crumb rubber (Table 6-13). The dermal and oral age-sensitivityweighted lifetime average daily doses for these chemicals are given in the Appendix (Sections F.6.2 and F.6.3), whereas the CSForal values are presented in Chapter 4 (Sections 4.5.3 and 4.6.3). The CSForal was used for both dermal and ingestion exposure routes. The mean and maximal cancer risks associated with the dermal route were below one in a million for all receptor categories. Table 6-15 shows the cancer risks for ingestion routes for the receptor categories. The mean and maximal cancer risks were below one in a million for most receptor categories for the ingestion route.
However, the mean cancer risk for the spectator category, and the mean and maximal risks calculated for the athletes showed a small excess risk. All dermal and ingestion cancer risk values can be found in Appendix Sections G.3.2 and G.3.3, respectively.
Table 6-15. Field-Specifica cancer risk (Riskder-sum-field) for dermal and ingestion exposures
Receptor
Category Age Group
Risking-sum-field x 10-6
Average of
Individual Fields
Range of Individual
Fields
Athletes
2<6 years 0.2 0.04 – 0.2
6<11 years 0.1 0.03 – 0.1
11<16 years 0.1 0.03 – 0.1
16<30 years 0.1 0.03 – 0.1
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Receptor
Category Age Group
Risking-sum-field x 10-6
Average of
Individual Fields
Range of Individual
Fields
30<40 years 0.1 0.01 – 0.1
40<50 years 0.0 0.01 – 0.04
50<70 years 0.1 0.02 – 0.1
Coaches
16<30 years 0.03 0.01 – 0.03
30<40 years 0.02 0.004 – 0.02
40<50 years 0.02 0.004 – 0.02
50<70 years 0.03 0.01 – 0.03
Referees
16<30 years 0.01 0.003 – 0.01
30<40 years 0.01 0.002 – 0.008
40<50 years 0.01 0.002 – 0.01
50<70 years 0.02 0.004 – 0.02
Spectators
Third trimester fetus 0.002 0.0004 – 0.002
0<2 years 0.9 0.2 – 0.9
2<6 years 0.3 0.07 – 0.3
6<11 years 0.2 0.06 – 0.2
11<16 years 0.02 0.004 – 0.02
16<30 years 0.01 0.002 – 0.01
30<40 years 0.01 0.002 – 0.01
40<50 years 0.01 0.002 – 0.01
50<70 years 0.01 0.003 – 0.01 a 35 field-specific Riskder-sum-field and Risking-sum-field are included in the table.
6.6.3. Multiple Routes of Exposure
OEHHA estimated the lifetime cancer risk of multi-route exposure to the field-related and non-field related carcinogens. Table 6-16 lists the lifetime incremental cancer risks from multiple routes of exposures. Overall, the cancer risk associated with field-related exposures was much less than from exposure to non-field-related chemicals (i.e., common air pollutants). Further, the calculated average cancer risk levels across all fields for all age groups of athletes, coaches, referees and spectators (on-field and offfield) were below the de minimis risk level of 1 in a million. As seen from Table 6-16, column 3, the field-related cancer risk levels for the 33 receptor groups in the 35 fields ranged from 0.002 to 1.1 in a million.
Examining the individual field-specific cancer risk values for field-related carcinogens (Table 6-16, column 5), one can see that:
• the lifetime excess cancer risk values for coaches were below 1 x 10-6 in all cases and ranged between 0.01 to 0.6 in a million.
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• the lifetime excess cancer risk values for referees were below 1 x 10-6 in all cases and ranged between 0.005 to 0.2 in a million.
• nearly all risk values calculated for the seven groups of athletes were below or very close to 1 x 10-6, with the individual field-specific risk values from 0.03 to 1.2 in a million.
• all risk values calculated for the spectators off-field were below 1 x 10-6, with the individual field-specific risk values ranging up to a maximal value of 0.7 in a million.
• except for infants (0<2 years), for all other groups of spectators on-field, the calculated cancer risk levels were below 1 x 10-6, with individual field-specific values ranging from 0.001 – 0.8 x 10-6. For infants (0<2 years) exposed to the turf-related chemicals on-field during 2 years, the calculated lifetime cancer risk ranges from 0.3 - 2.7 x 10-6. Given the additional application of an age sensitivity factor of 10 to calculate the cancer risk for infants (0<2 years) (OEHHA 2015), this risk level is low but of possible concern particularly because of the hand-tomouth activity and ingestion of crumb rubber infill in the turf fields.
Table 6-16. Lifetime Incremental Cancer Risk for Each Age Group and Receptor Category for Multiple Routes of Exposuresa
Receptor
Category Age Group
Risk x 10-6
Average of Individual Fields Range of Individual Fields FieldRelatedNon-FieldRelated Field-Related Non-FieldRelated Athletes
2<6 years 0.2 1.4 0.06 – 0.7 0.3 – 3.9
6<11 years 0.3 2.3 0.06 – 0.9 0.5 – 6.4
11<16 years 0.2 2.2 0.05 – 0.8 0.5 – 6.2
16<30 years 0.3 3.9 0.06 – 1.2 0.9 – 11
30<40 years 0.2 1.8 0.03 – 0.6 0.4 – 5.1
40<50 years 0.1 1.8 0.03 – 0.6 0.4 – 5.0
50<70 years 0.3 3.5 0.05 – 1.1 0.8 – 9.9
Coaches
16<30 years 0.1 1.6 0.02 – 0.5 0.4 – 4.5
30<40 years 0.1 1.0 0.01 – 0.3 0.2 – 2.8
40<50 years 0.1 1.0 0.01 – 0.3 0.2 – 2.9
50<70 years 0.1 2.0 0.02 – 0.6 0.4 - 5.7
Referees
16<30 years 0.04 0.6 0.01 – 0.2 0.1 – 1.7
30<40 years 0.03 0.4 0.005 - 0.1 0.08 – 1.0
40<50 years 0.03 0.4 0.005 – 0.1 0.08 – 1.1
50<70 years 0.1 0.8 0.01 – 0.2 0.2 – 2.1
Spectators
On-field
Third trimester
fetus 0.004 0.04 0.001 – 0.014 0.008 – 0.11
0<2 years 1.1 2.5 0.3 – 2.7 0.5 – 7.0
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Receptor
Category Age Group
Risk x 10-6
Average of Individual Fields Range of Individual Fields FieldRelatedNon-FieldRelated Field-Related Non-FieldRelated 2<6 years 0.3 0.8 0.08 – 0.8 0.2 – 2.2
6<11 years 0.3 0.9 0.07 – 0.8 0.2 – 2.6
11<16 years 0.04 0.4 0.01 – 0.1 0.09 – 1.1
16<30 years 0.02 0.2 0.006 -0.09 0.05 – 0.7
30<40 years 0.02 0.2 0.004 – 0.05 0.03 – 0.4
40<50 years 0.02 0.2 0.004 – 0.05 0.03 – 0.4
50<70 years 0.03 0.3 0.01 – 0.1 0.07 – 0.9
Spectators
Off-field
Third trimester
fetus 0.002 0.02 0.0 – 0.01 0.004 – 0.07
0<2 years 0.1 1.1 0.0 – 0.7 0.3 – 4.7
2<6 years 0.05 0.4 0.0 – 0.2 0.08 – 1.5
6<11 years 0.05 0.4 0.0 – 0.3 0.1 – 1.8
11<16 years 0.02 0.2 0.0 – 0.1 0.04 – 0.8
16<30 years 0.01 0.1 0.0 – 0.07 0.03 – 0.5
30<40 years 0.009 0.07 0.0 – 0.04 0.02 – 0.3
40<50 years 0.009 0.07 0.0 – 0.04 0.02 – 0.3
50<70 years 0.02 0.1 0.0 – 0.09 0.03 – 0.6 a Based on 35 field-specific RISKfield values.
6.7. References
OEHHA (2015). Air Toxics Hot Spots Program Risk Assessment Guidelines: The Air Toxics Hot Spot Program Guidance Manual for Preparation of Health Risk Assessments. Sacramento, CA, Office of Environmental Health Hazard Assessment, California Environmental Protection Agency.
USEPA (1989). Risk Assessment Guidance for Superfund Volume I Human Health Evaluation Manual (Part A). Washington D.C., Office of Emergency and Remedial Response, U.S. Environmental Protection Agency.
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Chapter 7. Discussion
7.1. Introduction
This study assessed the non-cancer hazards and cancer risks for athletes, coaches, referees, and spectators from acute and chronic exposures to chemicals at synthetic turf fields in California. This assessment was based on individual field data on chemical concentrations and the toxicity criteria (TC) for the detected chemicals. OEHHA also derived exposure parameters specific to each receptor category, based on results from three Time-Activity Studies targeting competitive soccer athletes in California.
OEHHA considered the exposure duration, exposure routes, exposure pathways, and toxicity endpoints in conducting the risk assessment. Specifically, this study focused on: (1) acute inhalation exposure to chemicals, (2) one-day inhalation, oral, and dermal exposure to DARTs (developmental and reproductive toxicants), (3) chronic inhalation exposure to sensory irritants, (4) chronic inhalation, oral, and dermal exposure to general toxicants, and (5) lifetime risk from exposure to carcinogens.
This section discusses the limitations and boundaries of the study, while acknowledging areas of variability and uncertainty. It also provides the main conclusions from this assessment.
7.2. Study Design and Unique Features
This OEHHA Study is a cross-sectional study to characterize exposure to chemicals released from crumb rubber on synthetic turf fields and assess the health risks. The study consisted of several core tasks including field characterization, exposure characterization, and risk assessment. Several key elements of the study’s protocols allowed OEHHA to obtain accurate and relevant chemical and exposure data for the health risk assessment:
• Use of state-of-the-art analytical instruments and computation algorithms, to identify field-related chemicals and non-field related pollutants, as well as bioaccessible chemicals from crumb rubber.
• Collection of air samples with the setup of a goal box in the middle of each field and scripted soccer activities to measure volatile organic chemicals (VOCs), semivolatile organic chemicals (SVOCs), and particulate matter. • Measurement of bioaccessible concentrations of chemicals in field crumb rubber samples to assess ingestion and dermal exposures.
• Derivation of exposure parameters for California soccer athletes based on timeactivity studies (TAS) and micro-level activity time series (MLATS), and • Compilation of toxicity criteria for turf-related chemicals through five complementary approaches.
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7.3. Study Boundaries and Limitations
The present study focused on the evaluation of exposure to chemicals that can be released from crumb rubber infill only. The backing materials and grass blade components of synthetic turf fields, and alternative infill materials are not included in the scope of this evaluation.
The study sampled 35 out of the approximately 907 fields across California. Using a stratified sampling plan (Section 2.3.1) the samples from 35 diverse fields provide representative chemical data for the evaluation of human exposure and assessment of human health risk.
During sample collection for this study, the state experienced a severe drought, resulting in widespread wildfires and subsequent deposition of fire-related chemicals across the State, such as polyaromatic hydrocarbons (PAHs) and metals. These events complicated the characterization of exposures of chemicals present at synthetic turf fields in California.
Recent reports published after the study was initiated revealed the presence in synthetic turf materials, particularly in the grass blades, of chemicals of emerging concern, such as N-(1,3-dimethylbutyl)-N′-phenyl-p-phenylenediamine (6PPD), N-(1,3-dimethylbutyl)- N′-phenyl-p-phenylenediamine quinone, and perfluoroalkyl substances (PFAS) (EWG, 2019; Lerner, 2019; Murphy and Warner, 2022; Tian et al., 2022; Tian et al., 2021). This study completed a non-targeted chemical analysis of the crumb rubber and did not detect PFAS. The suspected source of PFAS chemicals is not crumb rubber infill or air, the focus of this study, but the artificial turf blades. We did detect 6PPD, a known tire component, though our non-targeted analysis of crumb rubber did not detect or identify its transformation product (N-(1,3-dimethylbutyl)-N′-phenyl-p-phenylenediamine quinone).
The California Department of Toxic Substances Control (DTSC) identified that release of zinc from tires into water bodies could harm aquatic organisms (DTSC, 2021). Our study was initiated to address concerns about possible effects of crumb rubber materials on human health, and it therefore focused on human exposure and health hazards. Thus, OEHHA did not evaluate migration of chemicals to other environmental matrices and the potential health impacts on ecological receptors exposed through such media.
Other studies (Negev et al., 2022; Van Ulirsch et al., 2010) found lead (at levels exceeding federal statutory limit in synthetic turf fibers and surface dust at synthetic turf fields), trace metals, polycyclic aromatic hydrocarbons, and phthalates (in synthetic turf playground surfaces) in synthetic turf materials. The study measured bioaccessible concentrations of metals (including lead) in crumb rubber for evaluating ingestion exposure, as well as PAHs and phthalates in air (including vapor and fine particulate matters in air) and bioaccessible concentrations in crumb rubber for exposure via 4-275
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multiple routes. Due to logistical reasons, we were unable to collect adequate amounts of fine particulate matter from the air for metal analysis and therefore we did not assess inhalation exposure to lead in air on the fields. However, the California Attorney General has established an enforceable lead standard for synthetic turf (50 ppm) and requires manufacturers to replace fields with levels of lead exceeding the standard (CA DOJ, 2010).
7.4. Variability
There are several aspects and sources of variability in any health risk assessment. This OEHHA assessment considered the impact of variability in the chemical content of crumb rubber infills and other input parameters on the exposure of receptors in the synthetic turf fields.
7.4.1. Sample Heterogeneity
Crumb rubber infill is produced from a wide variety of automobile waste tires (different tire types, models, brands, production years, age in traffic). OEHHA considered this heterogeneity in an analysis of crumb rubber variation within a sample and within a field.
Each analysis was done on samples from a single field, for only those chemicals detected in the selected field, and the results applied for all individual fields. The full details of the analysis can be found in Appendix D.4.1.4.3. The results suggest that observed small variations present between individual samples and composites of those samples collected on a field have a low impact on the results of the health risk assessment. Therefore, OEHHA applied the assumption of similar variability for all chemicals detected on each of the 35 individual fields.
7.4.2. Time-Activity and Exposure Parameters
The present study conducted California-specific TAS to derive athlete-specific physical parameters and soccer-specific exposure parameters for exposure evaluation of synthetic turf field users.
Overall, OEHHA applied mean values in exposure evaluation. OEHHA considered the potential of using mean, 95th percentile and maximum values for athletes in the study.
Uncertainty in the survey results due to response bias, such as differences in interpretation of the terms used in the questions or memory bias, made applying the 95th percentile and maximum values challenging. For example, a very small number of survey participants provided these higher-end responses regarding the number of hours and days spent on the field (i.e., 16 hours a day each of the week). Using this small number of respondents as the most likely scenario on synthetic turf fields would overestimate exposure on synthetic turf fields for most soccer athletes. Additionally, by combining 95th percentile or maximum values for various parameters (i.e. annual event time, AET, Appendix Section B.2.5) that were not provided by the same participant, unrealistic scenarios could be created such as exposure times of 16 hours per event for 4-276
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both practices and games and event frequencies greater than 706 events per year which would indicate more than 2 practices and/or games a day. As a result, OEHHA chose to adopt mean values for soccer-specific activity exposure parameters.
7.4.3. Athlete Player Position
Within the athlete receptor group, OEHHA received survey responses from players of different positions, including forwards, defenders, midfielders, and goalies. Following public concern of high exposure to chemicals for goalies due to frequent diving activity and potential of ingesting crumb rubber, OEHHA evaluated survey responses for those participants as a separate exposure group. OEHHA’s evaluation for goalies did not reveal a large difference from the values derived from all participant data. Based on the small participant number (about 100 participants responded they play in the goalie position) and lack of data for many age groups (the TAS survey only received goalie data for the 11-16 and 16-30 years age groups), this study used a goalie-specific scenario to compute risk values for the all-athlete scenario.
7.4.4. Combined Receptor Scenarios
OEHHA evaluated risk for each receptor category separately and did not assess risk for combined-receptor scenarios. For specific and rare scenarios in which a person acts as multiple receptors during a single event or during a year, the time-adjusted hazard index and combination of cancer risk values can be performed based on the results presented in Chapter 6. Since essentially all age-specific and receptor-specific hazard indices and cancer risk values are well within the acceptable benchmarks, the likelihood of significant health risk during realistic combined-receptor scenarios is low.
7.5. Uncertainty
The following sections discuss the areas of uncertainty in the present study and specifically these relate to uncertainties in source characterization, exposure assessment and dose-response assessment, specifically focusing on toxicity criteria for chemicals detected on synthetical turf fields.
7.5.1. Chemical Characterization and Source Designations In this study, one critical aspect was the designation of chemicals as field-related or non-field-related. For reasons such as, but not limited to, field location (i.e. next to roads or in industrial areas), the use of power generators on fields where no power inlets were present, and changes in wind direction and speed during sampling events, chemicals detected in air and crumb rubber may have sources other than the synthetic turf field itself. Without the actual background samples to determine background chemical levels at fields, this study (i) examined concentration profiles for chemicals sampled in air on fields and (ii) performed extraction on fresh crumb rubber and field samples to determine the field-related chemicals. Chemicals found to have concentrations that 4-277
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decrease as sampling height increases, and chemicals detected in the crumb rubber extraction, were designated as field-related. For chemicals that were not collected in stratified samples, OEHHA used available regional air monitoring data to determine the likely source of those chemicals. Any chemicals not determined to be field-related were considered as non-field-related. These assumptions are a source of uncertainty in this risk assessment particularly as to the contribution of hazards and risks from chemicals with field-related sources versus those from non-field related sources.
For chemicals detected on-field, OEHHA applied concentration data collected from the air to derive acute inhalation exposure concentrations (Acute Cinh), chronic inhalation exposure concentrations (Chronic Cinh), and average daily doses of chronic inhalation exposure (ADDinh) for each organic chemical detected in the air. Additionally, OEHHA used bioaccessible concentrations of chemicals detected in artificial sweat extract and gastrointestinal fluids extract of crumb rubber samples (Cder-crumb rubber and CGI-crumb rubber, respectively) to derive average daily doses for chronic exposures via dermal and ingestion routes (ADDder and ADDing). We were unable to confirm all the tentatively identified chemicals in the samples due to limitations on a) availability of high purity reference standards, b) sensitivity of instruments controlled the resolution of peaks among many chemicals in the extracts, and c) coeluted chemicals with highly similar structure like isomers shared very similar behavior in the separation columns. These factors limited the number of chemicals identified for field characterization purposes.
The chemicals off-field were identified following collection of five consecutive hourly samples for VOCs, a three-hour large volume sample for SVOC and particulate matter from air at a nearby, off-field, and upwind location for each field. Ideally, the only difference between on-field and off-field locations would be the presence of synthetic turf materials on the field. Actual field conditions, however, did not always allow for this occurrence. Following the installation of a field, continual migration of chemicals to offfield areas is likely to have occurred through various mechanisms like windblown crumb rubber dusts and migration of SVOCs to surfaces off the field. Also, even though we tried to position the off-field samplers at an upwind location of each field, changes in wind direction during the sampling period sometimes resulted in an off-field sampling location no longer being truly upwind from the field. As a result, the measured off-field chemical concentration data might not reliably reflect background (non-field-related) exposure conditions for athletes, coaches, or referees in the study.
7.5.2. Exposure assessment
The exposure parameters for coaches, referees, or spectators were based on TAS collected in athletes. This approach introduced uncertainty in the exposure and risk assessments for these groups regarding the amount of time each group would spend at the field. However, OEHHA used the highest mean values of the athletes’ data for practices and games for the other receptor groups to be health-protective. 4-278
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Further, the TAS survey data did not collect any information on the amount of crumb rubber particles that might be directly ingested during the course of soccer activities.
However, participants did report it occurring. Without protocols to measure the ingested amount of crumb rubber, OEHHA used data in the literature to estimate the direct ingestion amount. This amount is likely to be a conservative overestimate in the exposure and risk assessments.
For DARTs, OEHHA assumed that a single exposure event may be sufficient to cause developmental and reproductive adverse outcomes. Therefore, for all exposure routes, an event frequency (EVDART) equal to 1 event per day was used. For inhalation exposures, chemical concentration for a less-than-24-hours-per-day exposure was adjusted, using the average volume of air inhaled during a field event (Vevent) to account for an exposure based on the different exertion levels and breathing volumes during a soccer event.
7.5.3. Dose-Response Assessment
7.5.3.1. Non-carcinogens
To evaluate a health protective non-cancer hazard of multiple route exposures to chemicals at synthetic turf fields, OEHHA used available information and healthprotective approaches in developing the toxicity criteria to be used in the hazard and risk assessment of human exposure to chemicals detected in air and crumb rubber samples collected from synthetic turf fields.
For chemicals with established toxicity criteria, the approach was to select the most health-protective value based on the most sensitive toxicity endpoint. Priority was given to recent assessments with higher quality studies, comprehensive review of the studies, and analyses using current risk assessment methodologies. In addition, OEHHA developed new screening level toxicity criteria for several chemicals, which are relevant for synthetic turf exposure scenarios.
For chemicals without established non-cancer toxicity criteria, OEHHA derived new toxicity criteria (either de novo or using route-to-route extrapolation, where appropriate) or identified structural analogs and used their established values. In some cases, no toxicity values could be derived or were available for analogs resulting in no toxicity assessment for those chemicals. The uncertainties associated with these methods is discussed below.
OEHHA applied one-hour toxicity criteria (Acute TCinh) for acute inhalation exposure to 11 volatile organic chemicals and carbonyls detected in air at synthetic turf fields.
OEHHA had not established Acute TCinh for the other 108 organic chemicals detected in air. Absence of scientific evidence on toxicities for acute inhalation exposure to these chemicals was one of the reasons for the lack of established acute inhalation toxicity criteria. Further, OEHHA determined that the limited number of chemicals with 4-279
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established 1-hour RELs were not sufficient for use as chemical analogs of these 108 detected chemicals. As a result, for chemicals lacking acute RELs, OEHHA used the available subchronic health guidance values from other peer-reviewed sources (USEPA PPRTV, ATSDR MRL) and found that exposures were well below even those health guidance values, indicating that there would be no concern for acute health hazards.
The assumption of similar toxicity is a potential source of uncertainty due to the use of analog chemical values. Fourteen chemicals were assigned to the DART group based on the toxicity of analogs. Treating these chemicals as DARTs for exposure calculations introduced uncertainty in the exposure assessment since a single day rather than average exposure is assumed. The interpretation of the resultant hazard should take into consideration this assumption about toxicity. For other endpoints (general chemicals), 66 chemicals had toxicity criteria based on analog values. Using this approach allows the exposure of more chemicals to be included in the risk assessment, however the toxicity could be over- or under-estimated with analog assignment. The use of the route-to-route extrapolation approach for toxicity criteria adds additional uncertainty to the interpretation of the hazard or risk. For this study, toxicity criteria from the oral route were applied to the inhalation exposure of some chemicals and dermal exposure of all chemicals detected. Extrapolation is a conventional practice in risk assessment and in the absence of data, it is reasonable to assume same systemic toxic effects. However, due to lack of pharmacokinetic information to compare the disposition of the chemicals between routes, it is unknown whether this approach leads to over- or underestimation of toxicity.
7.5.3.2. Carcinogens
OEHHA used benzo[a]pyrene (BaP) potency equivalency factors (PEF, see Section
4.4.5) to derive cancer toxicity criteria and assess the risk associated with exposure to carcinogens when established chemical-specific cancer slope factors (CSFs) were not available. PEFBaP are potency factors applied to PAHs for which potency values derived with chemical-specific carcinogenicity data cannot be developed. They are estimated using BaP as the reference chemical. PEFBaP provide a relative estimate that is more likely and better to reflect the specific PAH toxicity than using an assumption of equal toxicity to BaP, which in most cases may overestimate toxicity (OEHHA, 2015). Of the 23 identified carcinogens, 16 chemicals had established chemical-specific CSFs, five chemicals had established PEF BaP, one chemical had a newly derived study specific CSF, and one chemical had a newly derived study-specific PEF BaP.
Thirteen chemicals were assessed in a single pathway with chemical specific CSFs.
Ten carcinogens were assessed for risk in all three exposure pathways. Of those assessed in multiple pathways, three had chemical-specific CSF and route-to-route extrapolation was used to apply the CSF for some routes. There is uncertainty with route-to-route extrapolation as differences in deposition, absorption, and metabolism between routes can result in over- or underestimation of the calculated risk. 4-280
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For metals and metalloids, for either non-cancer or cancer effects, the most health protective value was selected regardless of their oxidation state and anion. For example, we assumed all chromium in the crumb rubber to be chromium VI instead of the generally less toxic anion chromium III. This approach was used because the actual state and anion in the crumb rubber are unknown. It adds uncertainty in the toxicity assessment and may lead to over-estimation of the risk for some metals and metalloids.
7.6. Cancer and Non-Cancer Risk Characterizations for Artificial Turf Field Users This study characterized health risks to artificial turf field users, by focusing on the following health outcomes from exposures to chemicals from crumb rubber infill:
• Acute inhalation toxicity
• Developmental and reproductive toxicity
• Sensory irritation
• General chronic toxicity, and
• Lifetime cancer risk
Each assessment was conducted based on detected chemicals that were likely to cause the specific non-cancer hazard or cancer risk, so the chemicals included in each assessment varied and few overlapped in the five outcomes. For non-cancer health hazards, a hazard index (HI) of 1 is considered to not present a health hazard and any exceedance of this value would indicate an increasing but undefined likelihood that adverse health impacts may occur, particularly in sensitive individuals. For cancer risk, a value at or below one excess cancer in a population of one million people over a lifetime of 70 years is considered a negligible risk or de minimis risk level.
Four receptor categories, namely, athletes, coaches, referees, and spectators were evaluated in this study and they were further divided into appropriate age groups. The study results indicated that:
• Acute exposure such as 1 hour intermittent exposure to artificial turf field-related or non-field related chemicals would not be associated with acute health hazards to any receptor. The acute hazard index from the single field-related and 10 nonfield-related acute toxicants evaluated in this study is less than 1. • One-Day exposure to developmental and reproductive toxicants, on average, was associated with a HI of less than 1 (0.01 to 0.58) for all receptor and age groups. The calculated maximum HIDART among the 35 fields was above 1 (range of 1.2 to 1.8) for athletes 11-70 years. When HIDART exceeds 1, there is increasing but unquantified probability of health effects. The HIDART of 1.2 – 1.8 in athletes of 11-70 years calculated in this study is the result of combination of “worst-case”, health-protective assumptions and parameters used in exposure assessment as detailed below:
o The exposure assessment assumed a “worst case” summation of chemical doses received through (i) inhalation exposures during 2.3 to 3.1 4-281
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hours per event (game or practice); (ii) ingestion exposure of 292 to 315 mg crumb rubber per event and (iii) dermal exposure through skin load of 142 – 180 mg crumb rubber per event. The odds of all these actually occurring is very low, thereby indicating low probability of observing HIDART exceedances of 1.2 – 1.8.
While the HQ of each chemical taken individually for each age group of each receptor group was below 1, the sum total of HQs for the 24 chemicals, i.e., HIDART, exceeded 1 in athletes 11-70 years primarily due to inhalation exposures to benzo(a)pyrene. The toxicity criterion for benzo(a)pyrene was calculated using an uncertainty factor of 3000. This means that the reference health guidance value for humans is 3000 times less than the lowest concentration at which adverse effects were observed in animals, to account for data gaps on the health effects of benzo(a)pyrene. As the maximal HIDART of 1.2 – 1.8 calculated in this study for athletes of 11 – 70 years old is very small compared to the factor of 3000, it indicates a low probability of, and concern for, developmental and reproductive health effects.
• Chronic exposure to sensory irritants: The mean individual field HIsensory for the single field-related and 2 non-field-related sensory irritants among the 35 individual fields were all below 1. The maximum individual field HIsensory was 1.9, within 2-fold of the level of concern, with 99.9% of the hazard originating from the non-field-related irritants, which are common air pollutants and not coming from the turf infill.
• Chronic exposure to general chemicals: The HI method used in this study assumes that the chronic health effects of the various chemicals are additive.
This method is a simplification of the HI concept because it only considers the four coarse endpoints (acute, DART, sensory irritants, and general chemicals) and does not consider the specific target organs (liver, kidney…) and toxicity mechanisms of the various chemicals. The mean individual field HI for general chemicals, for combined exposure to field and non-field related chemicals, was below 1 (range of 0.03 to 0.5) for all receptors. While the maximum value of the individual field HI for combined field-related and non-field-related chemicals did not exceed 1 in athletes, referees and coaches, it was 1.2 for spectators 0<2 years of age. Of the 99 field-related chemicals contributing to the HI, lead was the driver, contributing to 66% of the total value through the ingestion of crumb rubber from the fields, particularly by the hand to mouth activity. When the HI exceeds 1, there is increasing but unquantified probability of health effects; the HI was 1.2 in this study for spectators of 0-2 years old and it was based on the following “worst-case” combination of health-protective exposure parameters and assumptions:
Inhalation of air during 397 hours per year (with the duration of each event ranging from 2.1 to 3.1 hours per day)
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Dermal load of 48 mg of crumb rubber per event during 161 events (games and practices) per year
Ingestion of 153 mg of crumb rubber per day (ie., during attendance at a game or practice during 161 days per year)
Given that the odds of these exposures actually occurring is low, there is a low probability and concern of health effects in spectators 0-2 years old. The HI in infants will be closer to 1 (ie., no concern of health effects), if any of these exposure parameters are lower, particularly the amount of crumb rubber ingested per day of event.
• Lifetime cancer risk: The cancer risk estimates from this study indicate very low additional risk for the synthetic turf field users. The mean individual field risk for combined exposure to field- and non-field-related carcinogens exceeded 1 x 10-6 for all receptors, with the cancer risk being driven primarily by the non-fieldrelated carcinogens.
The calculated average cancer risk levels, associated with the field-related chemicals, across all fields for all age groups of athletes, coaches, referees and spectators (on-field and off-field) were below the de minimis risk level of 1 in a million. The range of calculated cancer risk in some but not all fields exceeded 1 x 10-6 by a small extent, specifically for athletes (0.03 to 1.2 in a million) and infant spectators on-field (0.3 to 2.7 x 10-6). In these two particular groups, the maximal risk value was slightly above 1 in a million lifetime risk, and it is a result of the “worst-case” combination of health-protective assumptions and parameters used in exposure assessment:
o Inhalation exposure of infants and athletes during 2.1 to 3.1. hours per event (161 events per year for infants; 138 to 214 events for athletes); o Oral exposure of infants to 153 mg crumb rubber per event during 161 events per year, and of athletes to 115 to 176 mg crumb rubber per event day during 138 to 214 events per year; and
o Dermal exposure to a skin load of 48 mg of crumb rubber per event during 161 events per year in infants, and 168 – 179 mg crumb rubber per event during 138 – 215 outings per year for athletes of 16-30 years and 50-70 years old.
Given the low odds of all these exposure scenarios and parameters actually occurring, the estimated cancer risks do not raise to moderate or significant level of concern.
7.7. Conclusions
Overall, this risk assessment study found no significant health risks to players, coaches, referees and spectators from on-field or off-field exposure to field-related chemicals in crumb rubber infill from synthetic turf fields based on available data. Specifically, the evaluations of acute toxicity, developmental and reproductive toxicity, sensory irritation, general chronic toxicity and cancer risk in all receptor groups were within acceptable 4-283
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March 2025
benchmarks with very few exceptions. Considering the health-protective, “worst-case” assumptions and parameters used in the exposure assessment, the small exceedances in the few instances (developmental and reproductive toxicity for athletes aged 11 to 70 years; chronic toxicity in spectators of 0 to 2 years old; excess cancer risk in infant spectators and athletes 16 to 30 years) associated with turf field-related chemicals are of low probability and of low concern, and would not require further evaluation.
7.8. References
CA DOJ (2010). "Brown Reaches Settlement to Reduce Children's Lead Exposure in Artificial Turf." from https://oag.ca.gov/news/press-releases/brown-reaches-settlementreduce-childrens-lead-exposure-artificial-turf.
DTSC (2021). DTSC to Explore Alternatives to Manufacturing Tires with Chemicals that Threaten Aquatic Life and Waterways.
EWG (2019). "New Studies Show PFAS in Artificial Grass Blades and Backing." 2023, from https://www.ewg.org/news-insights/news/new-studies-show-pfas-artificial-grassblades-and-backing.
Lerner S (2019). "Toxic PFAS Chemicals Found In Artifical Turf." 2023, from https://theintercept.com/2019/10/08/pfas-chemicals-artificial-turf-soccer/.
Murphy M and Warner GR (2022). Health impacts of artificial turf: Toxicity studies, challenges, and future directions. Environ Pollut 310: 119841.
Negev M, Barnett-Itzhaki Z, Berman T, et al. (2022). Hazardous chemicals in outdoor and indoor surfaces: artificial turf and laminate flooring. J Expo Sci Environ Epidemiol 32(3): 392-399.
OEHHA (2015). Air Toxics Hot Spots Program Appendices G-J: Guidance Manual for Preparation of Health Risk Assessments. Sacramento, CA, Office of Environmental Health Hazard Assessment, California Environmental Protection Agency.
Tian Z, Gonzalez M, Rideout CA, et al. (2022). 6PPD-Quinone: Revised Toxicity Assessment and Quantification with a Commercial Standard. Environmental Science & Technology Letters 9(2): 140-146.
Tian Z, Zhao H, Peter KT, et al. (2021). A ubiquitous tire rubber-derived chemical induces acute mortality in coho salmon. Science 371(6525): 185-189.
Van Ulirsch G, Gleason K, Gerstenberger S, et al. (2010). Evaluating and regulating lead in synthetic turf. Environ Health Perspect 118(10): 1345-1349. 4-284