Evaluation of Potential Exposure to Metals in Laundered Shop Towels

ABSTRACT

We reported in 2003 that exposure to metals on laundered shop towels (LSTs) could exceed toxicity criteria. New data from LSTs used by workers in North America document the continued presence of metals in freshly laundered towels. We assessed potential exposure to metals based on concentrations of metals on the LSTs, estimates of LST usage by employees, and the transfer of metals from LST-to-hand, hand-to-mouth, and LST-to-lip, under average- or high-exposure scenarios. Exposure estimates were compared to toxicity criteria. Under an average-exposure scenario (excluding metals’ data outliers), exceedances of the California Environmental Protection Agency, U.S. Environmental Protection Agency, and the Agency for Toxic Substances and Disease Registry toxicity criteria may occur for aluminum, cadmium, cobalt, copper, iron, and lead. Calculated intakes for these metals were up to more than 400-fold higher (lead) than their respective toxicity criterion. For the high-exposure scenario, additional exceedances may occur, and high-exposure intakes were up to 1,170-fold higher (lead) than their respective toxicity criterion. A sensitivity analysis indicated that alternate plausible assumptions could increase or decrease the magnitude of exceedances, but were unlikely to eliminate certain exceedances, particularly for lead.

Key Words:

• risk assessment
• occupational exposure
• dermal exposure
• metals
• lead
• cadmium

ACKNOWLEDGMENTS

This work was funded by the Kimberly-Clark Corporation, which also set up and paid for the testing program and obtained the LST usage information from company managers. In addition Joel Brostin of Kimberly-Clark provided the SEM images of the LSTs (Figures 1–3) and the SEI image of one of the particles found on a LST (Figure 4).

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Notes

Editor's note: Proposition 65, the State of California's Safe Drinking Water and Toxic Enforcement Act of 1986, was enacted as a ballot initiative in November 1986. The Proposition was intended by its authors to protect California's citizens and the state's drinking water sources from chemicals known to cause cancer, birth defects, or other reproductive harm, and to inform citizens about exposures to such chemicals. Proposition 65 requires California's Governor to publish, at least annually, a list of chemicals known to the state to cause cancer or reproductive toxicity.

In evaluating the potential for toxicity, it is important to consider the amount of a chemical that is absorbed into the bloodstream, since it is the absorbed form of the chemical that is typically of toxicological concern. Following ingestion, a chemical may not be completely absorbed into the bloodstream; some fraction of the dose may pass through the gastrointestinal tract unabsorbed. This phenomenon is reflected in the term “relative bioavailability.” Bioavailability is dependent on a number of factors, including chemical form, solubility, and particle size (Valberg et al. 1997).

Disclaimer: The conclusions in this article are derived from the exposure assumptions provided herein. Utilization of different exposure assumptions, or comparison to different LSTs (which may contain different concentrations of metals), could affect the conclusions.