Product stewards may have to rethink how they measure exposure to volatile chemicals
When assessing risk, product stewards often rely on mathematical models to estimate hazard and exposure to chemicals. Exposure amounts are based on assumptions about the concentration of a chemical in the product, expressed in a formula describing its volatility. Unfortunately, the assumptions in a model cannot always accurately predict real life exposures. In some cases, a simulation study may be more appropriate.
“In a model, you control your conditions very precisely, whereas in a simulation study, the conditions and therefore the results are more variable and subject to forces you can’t predict,” says Alison Gauthier, senior scientist at Exponent. “Exposure assessment is complicated, but there’s no need to avoid it.”
Using real-time instrumentation, Gauthier and her team studied the use of a cleaning product to determine exposure volatile organic compounds (VOCs) in a cleaning product. “We were taking samples at short intervals along with the integrated sample,” she says. “We thought the grab samples would line up nicely with the overall exposure, but the data were nothing like that. We had to rethink how we were measuring the exposure.”
Gauthier will elaborate on her findings during the presentation Challenging Exposure Assessment Assumptions: A Volatile Cleaning Product Case Study, at Product Stewardship 2017. “The methodology and take- home messages can be applied to any volatile chemical in any product,” she says. “We don’t want to present our findings in a way that’s too technical, but we also want to demonstrate some of the nuances that come with performing simulation studies and exposure assessments.”
Because real-time exposure assessments aren’t always a viable option, Gauthier stresses that it’s important to know how and when they might be most useful. There is a strategic, tiered approach to performing exposure assessments, and oftentimes it begins with a screening level, but will get more refined from there. “The methods employed are usually dictated by who is asking the question and why. If we are constrained by time or budget, it is important to have a good understanding of how the results might change if we had more resources,” she says. “The range we get from a model’s results may change or get more precise as we include more and better methods.”
In the end, these methods are intended to help product stewards better understand the products their companies sell. “If something were to happen down the line and someone were to allege some fault with the product, the company is ready to say the risk is based on how the product is supposed to be used,” says Gauthier. “It’s not something we recommend every company do for every product they have, but there are ways to prioritize products or chemicals in products that warrant further investigation.”