A study suggesting potentially excessive exposure to heavy metals in laundered shop towels, reported in the July 20 edition of this Newsletter, has been met with skepticism about its objectivity, methodology, and conclusions.
Additionally, a Huffington Post story about the study, published on July 11, contains additional critical responses, as well as some support for continuing study of shop-towel distribution of heavy metals.
The PaintSquare News story, “Laundering Doesn’t Protect Against Heavy Metals, Study Shows,” described the results obtained by the environmental consulting firm Gradient when it studied heavy metals in laundered shop towels. Details about the Gradient study, “Evaluation of Potential Exposure to Metals in Laundered Shop Towels,” are available in a White Paper.
The study found there is a likelihood of unsafe exposure levels to 7 heavy metals, including lead, among workers using the typical number of laundered shop towels per day.
Questions about Objectivity
Two PaintSquare News readers, Karen Fischer and Robert Ikenberry, noted that the study was sponsored by a stakeholder, Kimberly Clark, which makes competing disposable shop towels. Additionally, Kevin D. Schwalb, a spokesperson for those on the other side of the issue (favoring use of reuseable shop towels), the Textile Rental Services Association, criticized the study as being “profit-driven and baseless,” according to the Huffington Post story.
Some methodological issues in the study were called into question: the small sampling size (26 facilities that use laundered shop towels) was noted by Schwalb, and the presumed transfer efficiency from towel to mouth, which is based on studies of pesticides rather than heavy metals, was questioned by Ikenberry. He also questioned the underlying presumption in the study that heavy metals in the laundered towels would be disturbed by human handling when they were not dislodged by laundering.
Regarding the conclusions of the study, one toxicology expert, Alfred Bernard of Catholic University of Louvain, in Belgium, noted with skepticism the “astonishingly elevated metal concentrations” found in the study and urged caution in interpreting the data, according to the Huffington Post.
The authors of the study, themselves, qualified their findings with the following Disclaimer: “The conclusions in this report are derived from the exposure assumptions provided herein. Utilization of different exposure assumptions, or comparisons to different laundered shop wipes (which may contain different concentrations of metals), could affect the conclusions.”
Barbara Beck of Gradient, the lead author of the study, was
contacted but was unavailable for comment.
Thank you for your consideration of the recent study from Gradient. I’d like to add a few facts to this discussion that you may not have considered. First, though, I should note that while Dr. Barbara Beck wasn’t immediately available for comment when you contacted her last Friday afternoon, she’s a wonderful source of information should you want to speak in the future.
This is the second study published on this subject by Gradient. The original paper, from 2003, was peer reviewed and established the model of exposure used in the updated paper. Recent testing shows that 26 of the 29 metals analyzed appeared over 90% of the time in the towels tested. It would be unusual to find a company using 26 metals as a part of their process. This extraordinary array suggests a co-mingling of towels between companies and might be considered an indicator of a less-than-perfected cleaning process.
The science of hand to mouth transference has long been established, as evidenced by the citations referenced for lead transfer from surface to hand in the recent California Office of Environmental Health Hazard Assessment Guideline. You can find it at http://oehha.ca.gov/prop65/pdf/2011handtomouthPb.pdf.
Regarding the sample size, at some point, one has to ask the question: “Are more tests going to be more meaningful to any given laundered shop towel user?” Kimberly-Clark Professional feels strongly that one of the most important findings of this study is the fact that 100% of the towels tested have evidence of heavy metals. If I were a person who used laundered shop towels, I would want to know what was in my towel. I would not want to take the risk of the long-term effects of exposure to high concentrations of heavy metals; I would want someone to be telling me about this unexpected risk. Kimberly-Clark Professional believes that not making the public aware of this issue would be irresponsible. Workers use laundered shop towels every day presuming that the towels are clean, but nothing could be further from the truth.