A TRSA news teleconference today detailed the findings of a study conducted by independent researcher ARCADIS for TRSA. The study concluded that the metals on shop towels are not harmful to employees who use these towels in the course of their work. These results were independently verified and have been submitted for peer review for publication in industrial hygiene scholarly journals, according to TRSA President & CEO Joseph Ricci. Participants in the news teleconference included Dr. Kevin Connor, principal toxicologist, ARCADIS, Dr. Patrick Breysse, Johns Hopkins University, Joseph Ricci, president & CEO, TRSA and Brian Keegan, senior vice president, AmeriPride Services Inc.
“As the trade association representing facilities that process laundered reusable shop towels, we felt we had an industry responsibility to conduct a health assessment to quantify if any real health risk existed,” Ricci said. “This study reconfirms decades of experience, that laundered reusable shop towels are not only safe but are the most efficient, cost-effective and sustainable option.”
The study assessed the risk to workers on exposure to residual metal concentrations using data that represented the releasable quantity of each metal present in the laundered towels, Connor said. To analyze the residue of metals on the shop towels sampled, a leachability test procedure was used to model worker contact with the shop towel. A total of 27 metals, including antimony, beryllium, cadmium, cobalt, copper, lead and meliptinum were measured.
The samples were incubated in synthetic human sweat for one hour and the concentration of each residue in the extract or leachate was used to represent the releasable quantity of each residue that could be transferred to the skin of each worker using the towel. Towel to hand, and subsequent hand to food or hand to mouth transfer, was developed within the risk assessment framework set by the U.S. Environmental Protection Agency (EPA) and other authoritative agencies.
“Residue metals in laundered shop towels do not present any health hazards to workers using those towels,” Connor said. “Worker exposures to 27 chemical elements modeled in this assessment were not above regulatory thresholds used to judge potential health hazards. For example, cancer risk estimated for arsenic was one in a million. This is at the lower end of the range of acceptable risk used by the U.S EPA for regulatory decisionmaking, which is a range of one in a million to one in 10,000.”
Breysse, a professor in the department of environmental health sciences at the Johns Hopkins University Bloomberg School of Public Health, reviewed the ARCADIS study and compared it to a previous study on shop towels conducted by Gradient. The Gradient study challenged the notion that clean shop towels were safe by suggesting that there’s increased risk associated with the chemicals that reside in the shop towels after they’ve been laundered.
After his evaluation, Breysse concluded that the methodology of the Gradient report was flawed. “We discovered that there was considerable uncertainty about the model that (Gradient) proposed in terms of the variables that governed what gets on the towel, what comes off the towel, what gets on the hand and what comes off the hand when it’s in your mouth,” he said. “In modern-day risk assessments, the approach is usually to assess that uncertainty and incorporate that uncertainty in the final model estimate. The Gradient risk assessment did not do that. The whole premise of the Gradient model was perhaps problematic and the face validity as a result called the whole process into question in terms of what they produce in terms of the ultimate risk numbers.”
The approach taken by the ARCADIS report gets around that entirely by looking at the leachate test, which is a more biologically defensible way to assess what can get off a towel and onto a person’s hand, Breysse said. “How much you get off the towel onto the hands is going to drive the whole risk from there. We think the Gradient study greatly overestimated that, and the ARCADIS study, using the leachate test probably comes closer to that.
"We also think the ARCADIS report is also probably more thorough because it considered not only towel to hand to mouth contact, but it considered hand to food transfer and towel to mouth as well. The ARCADIS report also considered variability by looking at the ranges of values that might be produced in some of their parameters that go into the risk assessment. Ultimately, I think the ARCADIS report provides a more comprehensive assessment of the risk associated with clean towel use.
“People use shop towels to clean their hands from dirt. The ultimate question that people have to ask each other is if you’re using clean shop towels and you have lots of metals on your hands is there any added risk to the metals that might reside in a clean shop towel after you’ve cleaned it compared to the amount of metals that you’re removing from your hands? Ultimately, the real world context of the study is people aren’t using clean shop towels on clean hands, they’re using clean shop towels on dirty hands. That concept, in addition to the risk assessment that the ARCADIS report provides, suggests strongly that there’s little or nothing to be concerned about with respect to using clean shop towels, in my opinion.”