NEWS from CPSC
U.S. Consumer Product Safety Commission
| Office of Information and Public Affairs | Washington, DC 20207 |
| FOR IMMEDIATE RELEASE July 30, 2008 Release #08-348 |
CPSC Hotline: (800) 638-2772 CPSC Media Contacts: (301) 504-7908 |
CPSC Staff Finds Synthetic Turf Fields OK to Install, OK to Play On
WASHINGTON, D.C. - The U.S. Consumer Product Safety Commission (CPSC) staff today released its evaluation (pdf) of various synthetic athletic fields. The evaluation concludes that young children are not at risk from exposure to lead in these fields.
CPSC staff evaluation showed that newer fields had no lead or generally had the lowest lead levels. Although small amounts of lead were detected on the surface of some older fields, none of these tested fields released amounts of lead that would be harmful to children.
Lead is present in the pigments of some synthetic turf products to give the turf its various colors. Staff recognizes that some conditions such as age, weathering, exposure to sunlight, and wear and tear might change the amount of lead that could be released from the turf. As turf is used during athletics or play and exposed over time to sunlight, heat and other weather conditions, the surface of the turf may start to become worn and small particles of the lead-containing synthetic grass fibers might be released. The staff considered in the evaluation that particles on a child’s hand transferred to his/her mouth would be the most likely route of exposure and determined young children would not be at risk.
Although this evaluation found no harmful lead levels, CPSC staff is asking that voluntary standards be developed for synthetic turf to preclude the use of lead in future products. This action is being taken proactively to address any future production of synthetic turf and to set a standard for any new entrants to the market to follow.
As an overall guideline, CPSC staff recommends young children wash their hands after playing outside, especially before eating.
A Video News Release will feature b-roll of synthetic turf in use, on-site and laboratory testing, and soundbites in English and Spanish.
Video Feed Satellite Coordinates
Wednesday, July 30, 2008
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Thursday, July 31, 2008
10:30 AM – 11:00AM ET
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For Technical Information, DURING FEED ONLY, contact Daniel Conboy at (800) 920-6397 x 221.
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CPSC Staff Analysis and Assessment of Synthetic Turf “Grass Blades”
CPSC staff identified synthetic turf products for analysis of total lead content and accessible lead. Staff obtained samples of turf that had been left over after installation or that became available when a field was dismantled. Staff also visited in-service synthetic turf fields, and used portable X-ray Fluorescence (XRF) testing equipment to detect the presence of lead in the product, as well as a portable field wiping apparatus to measure the exposure potential to the lead.
The staff considered that exposure to the lead present in some synthetic turf products could occur if some of the lead gets on children’s hands, perhaps when synthetic grass blades break or become worn and release small particles of lead-containing material. The lead on the children’s hands may then get transferred from their hands to their mouths through normal hand-to-mouth activity during or after playing on the field.
Analytical Methods
Lead Content
Small pieces of synthetic grass blades were dissolved in concentrated nitric acid using a microwave digestion. The digested sample solutions were then analyzed for lead content using inductively coupled plasma atomic emission spectroscopy.
Accessible Lead (Wipe Sampling)
Products found to contain lead were tested for accessibility of the lead; i.e., whether children using the product could be exposed to the lead that is present.
Staff adapted the approach for estimating exposure to lead from contact with lead-containing synthetic turf fields from the approach used to assess children’s exposure to arsenic from playing on playground structures built using chromated copper arsenate (CCA) pressure-treated wood
(Appendix A).
The wipe testing methodology developed for testing pressure-treated wood was used to measure transfer of lead from synthetic grass blades, with one modification. Ghost Wipe™ was used in place of the polyester cloth wipe used in the wipe sampling for wood. Ghost Wipe™ is a commercially available wiping material, 15 cm x 15 cm, pre-moistened with deionized water, and sold in individually sealed packets. Company literature indicates that the Ghost Wipe™ meets all ASTM E1792-96E2 specifications for sampling materials for lead in surface dust.
The general method involves attaching a Ghost Wipe™ to a 1.1 kg weighted disk, 8 cm in diameter, installed in a device built to provide a standardized and consistent surface wiping. The disk is dragged down a 50-cm length of turf sample for 10 back and forth strokes. The wipe is then removed for analysis.
1 These comments are those of the CPSC staff, have not been reviewed or approved by, and may not necessarily reflect the views of, the Commission.
2 ASTM Standard E1792-96E, “Standard Specification for Wipe Sampling Materials for Lead in Surface Dust,”
ASTM International, West Conshohocken, PA, www.astm.org.
Results
Several of the products obtained by staff contained lead in the synthetic grass with concentrations ranging from 0.09 percent lead by weight to 0.96 percent. The testing showed that lead content varied between synthetic turf installations, and also within a field depending on color.
The data show that wiping of the surface of lead-containing synthetic turf with firm pressure results in transfer of some lead or lead-containing material to the wipe medium (Ghost Wipe™).
Exposure Assessment and Results
If it is assumed that transfer of lead-containing residue from the surface of synthetic turf has similar characteristics to transfer of arsenic-containing residue from wood (Appendix A) (i.e., that the amount of residue collected does not increase infinitely, but plateaus at some point during play), then the amount of lead that might collect on the hands of children as they play on turf fields can be estimated from laboratory studies of synthetic turf.
As discussed in Appendix A, the experimental wipe method using polyester cloths overestimated the amount of residue that might be transferred to a person’s bare skin by a factor of between five and 13 times, depending on whether a wet or dry cloth was used. Although the relationship between surface residue removal by a Ghost Wipe™ and bare skin has not been fully characterized, preliminary tests indicate that the Ghost Wipe™ overestimates to a similar degree the transfer of material from the turf surface to bare hands.
The staff believes that dividing the results obtained through use of using Ghost Wipes™ by five is a reasonable approximation of the amount of lead-containing material that may transfer to children’s hands.
The exposure assessment described above concerns the accessibility of the lead. Another important point to consider is the bioavailability of the lead, which relates to the amount of lead that is absorbed by the body. The staff assumed, in this case, that the bioavailability of lead from the material that transfers to skin from contact with lead-containing synthetic turf is the same as the bioavailability of lead from food and drink in the epidemiological studies of lead exposure.
The staff’s approach, based on the assessment of exposure to arsenic in pressure-treated wood, is that during play, lead-containing residue is transferred to a child’s hands and the n a portion of that “hand load” is transferred to the mouth during the day. The staff practice for assessing whether exposure to a product would result in excessive lead exposure is to assume that about half of the residue that collects on a child’s hands ends up in their mouths (i.e., transfer efficiency is 50 percent).
The staff used the wipe-testing data to estimate transfer of lead to children’s hands during contact with a synthetic turf surface during play. Each wipe value was divided by five to correct the overestimation of transfer using the Ghost Wipe™, and divided by two to account for the amount of lead that is transferred from the hands to the mouth.
CPSC staff recognizes a level of 10 micrograms of lead per deciliter of blood (10 mg/dL) as a level of concern with respect to lead poisoning. To prevent children from exceeding this level, the staff suggests that chronic ingestion of lead from consumer products should not exceed 15 mg lead/day3. This value was determined from epidemiological studies of ingestion of lead through food and drink (as discussed above with respect to bioavailability).
The results (Table 1) for this set of tested synthetic turf fields show no case in which the estimated exposure for children playing on the field would exceed 15 mg lead/day.
Study Limitations
This assessment is subject to a number of limitations including the accuracy of the wipe sampling method for estimating exposure to lead-containing residue from touching or other contact with the synthetic turf surface; the accuracy of the assumptions about the capacity of bare skin to collect surface residues during a typical play event at a field; and the accuracy of the assumptions related to hand-to- mouth transfer of lead-containing residues. Further, the staff did not make adjustments in its assessment to account for the non-uniformity of lead content of synthetic turf fields; i.e., some fields had striped areas that contained lead that constitute only a small part of the total playing surface of the field that otherwise had no detectable lead levels.
Children playing on such fields might have some contact with the lead-containing striped areas, but most of their contact with the surface would be expected to be with the other parts of the turf (not lead-containing). Finally, the bioavailability of lead from synthetic turf may not be the same as it is for the food and drink exposures that were the basis of the dose-response assessment used to determine the staff’s recommended 15 mg/day exposure limits for lead.
3 16 C.F.R. § 1500.230. Codified Guidance Policy for Lead in Consumer Products (63 FR 70648; December 22,
1998).
Appendix A
The staff’s previous assessment 4 of children’s exposure to arsenic from playing on playground structures built using chromated copper arsenate (CCA) pressure-treated wood informed the current approach to analysis of synthetic turf surfaces and the assessment of potential exposure to the lead contained in the turf “grass” fibers. Lessons learned from the CCA studies include:
1) Development of a treated wood sampling method: A saline-wetted polyester cloth wipe was attached to a 1.1 kg weighted disk, 8 cm in diameter. The disk was dragged down a 50-cm length of wood for 10 back and forth strokes. When compared to results of residue transfer using volunteers with bare hands, the polyester cloths picked up approximately 13 times more residue; the experimental values were multiplied by a conversion factor of 0.076 to get human skin equivalent hand loadings. When the polyester cloths were used dry, they picked up, on average, about 5 times more residue than the volunteer’s bare hands did.
2) Understanding of some of the characteristics of treated wood surface residues: Removal of surface residue arsenic correlated with several experimental design features including the material used to wipe the surface, whether the material was wetted or dry, the amount of force applied during wiping, and the area wiped. A key observation was that the amount of dislodged residue did not necessarily simply increase with changes in method that would likely remove more residue. Rather, the amount of dislodged residue approached a plateau, i.e., it appeared that the transfer of material depended on the capacity of the transfer medium (whether the skin of hands of volunteers or wipes made of cloth or other materials) to collect residue, which was not infinite.
3) Understanding of the nature of children’s contact with playground structures and potential exposure to surface residues: The data, in conjunction with activity analysis of children playing on playgrounds, led to the conclusion that despite the large variability in children’s playground activities and time spent at a playground, their hands would likely collect surface residues from the wood structures they happened to touch fairly quickly in a play session— what the staff termed “maximum hand loading”. For the exposure and risk analysis, then, the staff assumed that a child’s hands would become contaminated with an amount of arsenic as determined by the experimental study of residue transfer. Data from cloth wipes were adjusted for the finding that the cloth wipes always picked up more residue from the wood surfaces than the bare skin of volunteers.
4 Briefing Package, Petition to Ban Chromated Copper Arsenate (CCA)-Treated Wood in Playground Equipment
(Petition HP 01-3), February 4, 2003.
Table 1. Turf Sample Exposure Results and Health Hazard Evaluation
|
Firm |
Description |
Subsample |
Lead content (%) |
Wipe Sampling Result (µg) * |
Estimated daily ingestion of lead (µg) †‡ |
|
1 |
Green, installed 1999; removed 2008 |
1 |
0.54 |
65.8 |
6.6 |
|
2 |
0.56 |
98.7 |
9.9 |
||
|
3 |
0.55 |
39.9 |
4.0 |
||
|
Average |
|
68.1 |
6.8 |
||
|
1 |
Green, indoor field; installed 2000; in use |
|
0.88 |
14.3 |
1.4 |
|
1 |
Green; new, 2008 |
1 |
0.1 |
1.2 |
0.12 |
|
2 |
0.09 |
1.2 |
0.12 |
||
|
3 |
|
0.9 |
0.09 |
||
|
Average |
|
1.1 |
0.09 |
||
|
1 |
Green; new, 2008 |
1 |
0.42 |
1.3 |
0.13 |
|
2 |
0.47 |
0.4 |
0.04 |
||
|
3 |
|
0.4 |
0.04 |
||
|
Average |
|
0.7 |
0.07 |
||
|
2 |
Green and other colors; installed 2005; in use |
|
nd |
nt |
neg |
|
2 |
Green; unused sample sent to lab for analysis |
|
nd |
nt |
neg |
|
2 |
Green; unused sample sent to lab for analysis |
|
nd |
nt |
neg |
|
2 |
Green; unused sample sent to lab for analysis |
|
nd |
nt |
neg |
|
2 |
Green; unused sample sent to lab for analysis |
|
Trace |
nt |
neg |
|
2 |
Green; unused sample sent to lab for analysis |
|
nd |
nt |
neg |
|
2 |
Red; unused sample sent to lab for analysis |
|
nd |
nt |
neg |
|
2 |
Yellow stripes; field in use |
Sideline, 1 |
0.53 |
0.9 |
0.09 |
|
Sideline, 2 |
0.5 |
0.05 |
|||
|
Midfield |
2.4 |
0.24 |
|||
|
3 |
Green with yellow stripes; installed 2007; in use |
Green |
nd |
nt |
neg |
|
Yellow, 18 |
0.96 |
0.7 |
0.07 |
||