Barbara Beck of the consulting firm Gradient says the study builds upon an earlier analysis published in 2003 that concluded even after commercial laundering, the industrial towels studied retained elevated levels of heavy metals, which could result in worker exposure.
Gradient researchers compared the estimated amounts of ingested metals to various health-based criteria, including from the U.S. Environmental Protection Agency and the Agency for Toxic Substances and Disease Registry, part of the U.S. Department of Health and Human Services.
The study found, for the worker using the typical amount of towels per day, average exposure to seven metals -- antimony, beryllium, cadmium, cobalt, copper, lead and molybdenum -- may exceed health-based exposure guidelines set by U.S. government agencies.
Excessive metal exposure over time may present a health concern, Beck says.
Workers cannot see, smell, or feel heavy metal contaminants on "clean" laundered shop towels, and workers who touch towels with their hands may unknowingly transfer these metals from their hands to their mouths, ingesting the metals, Beck says.
The study, funded by Kimberly-Clark Professional, also found of the 29 metals studied, 26 were found on more than 90 percent of the towels tested, perhaps because launderers combine towels from multiple industries before washing.