Zinc for Dummies

Occurrence of Bromine, Lead, and Zinc in Synthetic Turf Components
Philip Dickey, Staff Scientist, Washington Toxics Coalition
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Zinc
Zinc was detected at 6.75% and 6.81% in two tests of the Forever Green infill material
(Figure 4b) and at 9.33% in the Motz infill (spectrum not shown). It was also detected at
between 4.03% and 6.97% in the SprinTurf samples (e.g. Figure 4f), which were turf and
infill mixed. Zinc was also detected at lower levels in the ARMS ProPlay shock pad
(Figure 4c). It was not detected in the ARMS infill material (Figure 4d). Note that the
ARMS infill material is coated silica sand rather than rubber. Our non-detects for zinc
and lead in this material are consistent with testing commissioned by the manufacturer
(Pb <1 .5="" 0.425="" p="" ppm="" zn="">Zinc oxide or zinc stearate are used as activators in rubber used in car tires. (12)
The concentrations we measured in infill material are higher than the percentages implied by
Wik and Goran (2-5% zinc oxide + fatty acid or zinc stearate). A typical MSDS for
crumb rubber lists the following zinc components: zinc oxide fume <3 and="" oxide="" p="" zinc="">total dust <3 p=""> It also lists approximately 20% naphthenic/aromatic oil. Another MSDS
cryogenic rubber lists zinc oxide at 1-5%.(14)
Zinc is a necessary human nutrient that has relatively low toxicity to humans but is more
toxic to aquatic life. A recent study for the Norwegian government used data from
laboratory measurements of zinc leachate from artificial turf fibers and rubber infill to9
calculate total zinc leached from a hypothetical turf pitch. A measured leachate
concentration of 3290 ppb lead to a prediction of 18.95 grams of zinc leached per year,
assuming a field of 7200 m2 and annual rainfall of 800 mm (31.5 inches). (15)
 The authors concluded that “the concentration of zinc poses a significant local risk of environmental effects in surface water which receives runoff from artificial turf pitches.”
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