October 10, 2023 / Lauren Gloekler, Heather Lynch, Andy Maier, and Taylor Tarpey

Resources and Approaches for Dermal Exposure and Risk Assessment

AIHA and the Foundation for Chemistry Research and Initiatives (FCRI) are hosting a series of workshops on occupational risk assessment. The key topics covered in this series include identifying and assessing the quality of data, exposure models, dermal exposure assessment, and risk characterization and management.

The fourth webinar in the Many Paths – One Goal series, which was held on Sept. 21, brought together a panel of experts in toxicology, industrial hygiene, regulatory issues, and engineering to discuss methods and tools for assessing risks to workplace dermal exposures. The experts presented information for estimating dermal exposure, approaches for setting health-based benchmarks, and strategies for optimizing and evaluating exposure control strategies.

Based on the state of the science for dermal risk assessment, there are several important factors to consider when evaluating exposure and risk potential. Many factors influence external exposure doses (that is, how much deposits on the skin) including the mass of the substance loaded on the skin from direct contact, transfer from surfaces, and air deposition. Factors affecting dermal transfer to the skin from contacting surfaces include the texture of the contact surface, pressure, duration of contact, and the number of contacts. The workshop highlighted the growing need for scenario-relevant data for these factors.

Regarding potential effects, the skin acts as both an exposure route and as a target organ; both local and systemic effects need to be considered. Several organizations have resources on conducting full hazard characterizations and deriving quantitative exposure limits. The workshop panelists emphasized that the hierarchy of controls in occupational settings needs full consideration when there are potential risks from dermal exposure. Gloves are a common protection from dermal exposures, but when used for exposure control, users must ensure the gloves are effective.

Workshop speakers and panelists discussed the numerous sampling methods and tools OEHS professionals use in characterizing the potential for dermal exposure and hazards in the workplace. Several easily obtainable resources for identifying potential dermal hazards include safety data sheets, Globally Harmonized System (GHS) classification, and hazard assessment documents (for example, NIOSH skin notation profiles). These resources can be used together with a growing resource base of methods for developing quantitative limits such as surface limits and dermal OELs. Where deemed appropriate and necessary, dermal exposure can be estimated directly (for example, through dermal sampling) or indirectly (through modeled factor-based estimates based on workplace surface loading). In addition, tools for measuring integrated route exposures such as biological monitoring techniques can be employed.

During the panel discussion held in the second half of the workshop, discussants identified opportunities to enhance existing resources and share knowledge regarding tools that are currently available. For example, assessments are often time-sensitive but may be incomplete without comprehensive resources easily accessible to an OEHS professional. In addition, panelists agreed that further research and empirical data would improve current dermal models. In many cases dermal exposure models lack empirically derived data for key input values. The discussants indicated that estimating dermal exposure from specific pathways, such as skin to saliva, skin to clothing, and skin to skin, is challenging due to numerous data gaps. One panelist emphasized that understanding how factors such as repeated dermal contacts and skin hydration may influence transfer and absorption of chemicals is complex but necessary to further our understanding of potential risk. However, existing models are helpful in many situations, particularly as a screening tool.

Regarding benchmarks and OELs, the limitations of extrapolating from acceptable surface limits for quantitative estimates of risk were noted. Currently there are few published compilations of dermal or surface health benchmarks with which to compare empirical or modeled exposure data. However, AIHA and others have guidance on methods for derivation. These tools provide a strong base for semi-quantitative assessments of risk that inform risk management strategy.

Panelists emphasized that OEHS professionals must communicate within their organizations but also to downstream users about effective control measures for dermal exposures and appropriate PPE selection. In most cases, data on PPE efficacy are limited and testing methods may not fully consider workplace conditions.

Despite these limitations, participants agreed that there are many opportunities for collaboration among regulatory scientists, OEHS professionals, and health scientists to fill information gaps in dermal exposure.

The fifth and final workshop in the series will be held on Nov. 9 and will focus on risk characterization and management. The workshop will not be recorded, so anyone interested in occupational risk assessment should plan to attend. Registration for the series is required. The slides for the first four workshops are available from the AIHA website.

Lauren Gloekler, Heather Lynch, Andy Maier, and Taylor Tarpey

Lauren Gloekler, MEM, is a senior health scientist at Stantec.

Heather Lynch, MPH, DABT, is principal science advisor at Stantec.

Andy Maier, PhD, CIH, DABT, FAIHA, is the director of the nonprofit Occupational Alliance for Risk Science initiative and a principal health scientist at Stantec.

Taylor Tarpey, MPH, is a health scientist at Stantec.


Transdermal uptake from clothing

This article covers various skin exposure routes, such as direct contact, surface transfer, and air deposition. However, it overlooks a significant one: Transdermal uptake through clothing. In workplace, chemicals like semi-volatile organic compounds (SVOCs) can absorb into clothing and gradually transfer to the skin. Neglecting this poses risks, as employees can carry these chemicals to their homes and cars, leading to ongoing dermal exposure beyond the workplace. Recognizing clothing as a source of exposure is vital for comprehensive skin exposure assessment.

By Azin Eftekhari, Ph.D. on October 10, 2023 1:53pm

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