Education Details

• Monday, September 23, 2024 – 8:00 a.m.-9:00 a.m.
  Dermal Risk Assessment - An overview of EPA's methods and approaches to dermal risk assessment
  Presented by Jeff Dawson, U.S. EPA
• Monday, September 23, 2024 – 1:30 p.m.-2:30 p.m.
  Education, Intervention, and Control, Dermal Exposures in Additive Manufacturing
  Presented by Johan du Plessis, PhD, North-West University
• Tuesday, September 24, 2024 – 8:00 a.m.-9:00 a.m.
  Quantification of Methyl Salicylate Skin Exposure in Human Subjects
  Presented by Leena Nylander-French, University of North Carolina
• Tuesday, September 24, 2024 – 2:00 p.m.-3:00 p.m.
  A Proposal for Updating CIB 61: A Strategy for Assigning New NIOSH Skin Notations
  Presented by Jerry Kasting, PhD, University of Cincinnati
• Wednesday, September 25, 2024 – 8:00 a.m.-9:00 a.m.
  Skin health and mechanisms of toxicity following chemical exposure
  Presented by Stacey Anderson, NIOSH
  

Monday, September 23, 2024 – 9:30 a.m.-10:00 a.m.
Importance of Standardization in Surface and Dermal Exposure Assessment
Presented by Steven Verpaele, Nickel Institute

• There is growing interest in surface and dermal sampling and measurement of contaminants in workplace and other indoor settings. The Toxic Substances Control Act (TSCA) in North America and the registration, evaluation, authorization and restriction of chemicals (REACH) in Europe are driving legislations for introducing limits for various chemicals related to skin and surface exposure. In addition, ACGIH has established the Threshold Limit Value–Surface Limit (TLV–SL) as the concentration on workplace equipment and facility surfaces that is not likely to result in adverse effects following dermal exposure or incidental ingestion. Surface and dermal sampling are not currently a common practice, and apart from metals, metalloids and pesticides, there are few unambiguous measurement methods available. The development of consensus standards for sampling and measurement can help to overcome this shortcoming.
• This presentation will provide an overview of consensus standards that are available, under development, and proposed in different organizations (e.g., ISO, ASTM, and CEN).

Monday, September 23, 2024 – 10:10 a.m.-10:40 a.m.
ACGIH’s Surface Sampling Limits
Presented by Michael DeLorme, ACGIH TLV Committe

• Workplace activities can generate gas, liquid, and solid exposure atmospheres which leads to occupational exposures. Such occupational exposures have traditionally been assessed with quantitative air sampling techniques to determine inhalation exposure for comparison with an occupational exposure limit. In contrast, dermal exposure assessments have traditionally been qualitative in nature in the form of either a ‘Skin’ or ‘DSEN’ notation. While the ‘Skin’ or “DSEN’ notation informs the Industrial Hygienist to be aware of potential worker exposure by the dermal route, these notations provide no assessment capacity to know if a worker is potentially exposed to a dose of chemical that may result in adverse health effects. Subsequently, the Threshold Limit Value-Surface Limit (TLV-SL) has been derived to allow the Industrial Hygienist to assess employee workplace exposures by the dermal route to provide a more robust evaluation of employee exposure to chemicals. The TLV-SL is the concentration on workplace equipment and facility surfaces that is not likely to result in adverse effects following dermal contact. The TLV-SL is intended to supplement airborne TLVs and provide a quantitative criteria for establishing acceptable surface concentrations. This presentation will cover the basic methods that are used to derive a TLV-SL as well as the interpretation of wipe sampling data.

Monday, September 23, 2024 – 11:40 a.m.-12:10 p.m.
The methodologies underlying the recently proposed ACGIH TLV-SLs and AIHA ASLs are ill-conceived and not protective Presented by John Kissel, PhD, University of Washington

• Industrial hygienists have long sought surface load limits that would be analogous to air quality limits to distinguish acceptable and unacceptable work environments. However, the crucial link between surface loads and dose is a transfer factor that quantifies human interaction with environmental surfaces. Empirically derived transfer factors exist for some occupational tasks in agriculture but are generally not available for other industrial sectors. Recently ACGIH published methods for estimation of Threshold Limit Values® for Surface Loads (TLV®-SLs) for sensitizers and for systemic toxicants. In the absence of empirically based transfer factors, the derivation in each case relies upon assumptions that frequently have no empirical basis and are not, despite claims, conservative. However, AIHA has now also included the same approach for systemic toxicants in its Hazardous Drug Surface Contamination Guidance. Comparison of the approaches adopted by ACGIH and AIHA to long-standing methods used in agriculture (that are supported by extensive empirical data and that have been vetted against biomonitoring data) reveals the newer surface load limit methods to be non-protective.

Monday, September 23, 2024 – 9:30 a.m.-10:00 a.m.
First Responders’ Exposures, PFAS, and PPE
Presented by Bryan Ormond, PhD, NC State University

• In 2022, the occupation of firefighting was reviewed, and sufficient evidence existed to reclassify it as Group 1 known human carcinogen. All types of firefighters are routinely exposed to byproducts of combustion in the gases, vapors, smoke, and soot released from burning structures, vehicles, or wildlands. Several studies have characterized the composition of smoke during fire propagation and suppression showing that firefighters are exposed to significant amounts of volatile organic chemicals, polycyclic aromatic hydrocarbons (PAHs), flame retardants, and per- and polyfluoroalkyl substances (PFAS). Contact with these contaminants occurs despite the firefighters wearing their personal protective equipment (PPE), indicating that current PPE is not effective at mitigating fireground exposures. This presentation will discuss dermal absorption of fireground chemicals, more realistic evaluations of PPE performance, and how those methods can be extended to the field. In vitro flow-through diffusion experiments were carried out using porcine skin to assess the absorption of select PFAS and PAHs to provide a relative comparison of absorption. To assess the ability of PPE to mitigate dermal exposures to fireground vapors, system-level evaluations of various ensembles were conducted through the Man-In-Simulant-Test. Results of these evaluations indicate substantial limitations in current protective ensembles, specifically for dermal exposure to fireground vapors.

Monday, September 23, 2024 – 10:10 a.m.-10:40 a.m.
Biological Monitoring: The Method of Choice for Dermal Risk Assessment?
Presented by Kate Jones, HSE

• There are many challenges to dermal risk assessment, including a lack of information on percutaneous absorption for many chemicals, absence of a “gold standard” for surface and skin sampling techniques, limited interpretation for such methods, and uncertainties in models and in-vitro systems. Biological monitoring (human biomonitoring, HBM) offers the advantages of determining the actual systemic uptake of chemicals via all routes, including the skin. Although HBM does not exclusively assess skin uptake, it does provide a comprehensive measurement of the body burden arising from undertaking a particular job or task with all the exposure routes, control measures and behaviors taken into account. In many scenarios, skin contact will be the predominant route of exposure due to the nature of the task, the (low) volatility of the chemicals in use and/or the use of ventilation controls. The use of personal protective equipment (PPE), such as gloves and overalls, is often provided to prevent exposure to the skin but can actually exacerbate the issue if not considered properly and it is difficult to ensure the efficacy of PPE long-term. This presentation will provide examples of HBM in demonstrating the importance of skin uptake in the workplace, including the problems of relying on PPE. HBM provides a straightforward, practical means to demonstrate the problem of skin exposure even if the explanation of the problem requires additional techniques. Biological monitoring should therefore be the initial method of choice for dermal risk assessment.

Monday, September 23, 2024 – 11:00 a.m.-12:10 p.m.
Approaches to Skin Notations: NIOSH, ACGIH, and the MAK Commission
Presented by Naomi Hudson, PhD, Jerry Kasting, Michael Bader, Michael DeLorme

• The National Institute for Occupational Safety and Health (NIOSH) Skin Notation Profiles evaluates skin exposures from chemicals known to absorb onto or through skin and result in systemic, direct, and sensitizing effects. To assign a skin notation, NIOSH reviews scientific and technical data that include the physicochemical properties, human exposures and health effects, data from in vivo toxicity testing, in vitro laboratory testing, and mathematical models. Additionally, about 40 % of all substances with an occupational exposure limit in Germany have been assigned an ‘H’ designation by the MAK Commission of the Deutsche Forschungsgemeinschaft (DFG). The designation indicates that the percutaneous absorption of a substance under typical workplace conditions can make a significant contribution to the systemic exposure of an employee, and hence increase the individual health risk associated with the substance. A designation with ‘H’ is warranted when the percutaneous uptake exceeds approximately 25 % or more of the tolerable quantity. Procedures for assigning skin notations are periodically revised. The panel will describe current procedures at NIOSH, ACGIH, and the MAK Commission, and entertain suggestions for updating and improving Skin Notation Profiles. The principles, results, and challenges of the skin notation assignment process will be illustrated by some recent examples.

Monday, September 23, 2024 – 3:00 p.m.-3:30 p.m.
What can we learn from novel consumer product dermal sampling methods and assessments?
Presented by Renee Kalmes, CIH, Exponent

• Quantitatively characterizing dermal exposure from performing tasks involving handling or use of chemical-containing materials is challenging and complex, as many of the exposure assessment variables are scenario-specific. This session reviews some novel approaches being used to evaluate skin loading from contact with and use of phthalate and bisphenol A (BPA) containing materials. Phthalate and BPA skin loading data obtained from various exposure simulations methods (i.e., gloves, skin wipes) are presented, and comparisons with different sampling procedures are discussed. Calculation of the resultant dermal dose using the skin loading data and other exposure parameters is also reviewed. Although these methods are currently successfully being applied to assess skin loading from contact with consumer products, the utility of these approaches to evaluate dermal worker exposure in occupational settings is discussed.

Monday, September 23, 2024 – 3:40 p.m.-4:10 p.m.
Dermal Monitoring Decision Framework: A Case Study for TSCA Compliance for Dermal Exposure Data
Presented by Heather Lynch, Integral

• Dermal exposure is often not well characterized, particularly for workers handling industrial chemicals. Now more than ever, regulatory agencies quantitatively assess potential risks associated with dermal exposure, as demonstrated in recent TSCA risk evaluations. However, occupational exposure monitoring data are often not available. Many dermal assessment tools have been published, some of which may be used in lieu of occupational exposure data, but such tools have not been harmonized. Further, using overly conservative assumptions in the absence of occupational exposure data may mischaracterize exposure and prevent adequate prioritization of risks. First, we will briefly present an outline of our conceptual framework developed in collaboration with the Foundation for Chemistry Research and Initiatives (FCRI). Next, using a chemical listed by EPA as a priority compound as a case study, we will guide the audience through the steps outlined by our conceptual model, including problem formulation and initial data gathering, screening assessment, and development of a data collection strategy. We will use Q&A throughout the presentation to gauge how participants would proceed at different points of the dermal exposure framework, given the specifics of the case study. We will discuss resources for hazard and exposure data, including databases, published literature, and a recently compiled compendium of occupational dermal exposure factors. We will describe tools that can be used for screening level dermal assessments; for example, the AIHA DRAM tool, qualitative worksite assessments, and exposure factors. Through this interactive presentation, participants will have an opportunity to critically evaluate how to assess dermal exposure using our framework in the context of a case study.

Monday, September 23, 2024 – 4:20 p.m.-4:50 p.m.
Mattress Manufacturing - Bowtie Dermal Risk Assessment Model
Presented by Georgi Popov, PhD, QEP, CSP, ARM, SMS, CMC, FASSP, FAIHA, University of Central Missouri

• Polyurethane mattresses are popular and comfortable. However, the manufacturing of the mattresses involves toxic chemicals and creates skin exposure concerns.
  Mattress polyurethane is formed by mixing a polyol with Toluene diisocyanate (TDI) in the presence of suitable catalysts and additives.
  The purpose of this educational research project was to evaluate TDI exposures utilizing field methods and newly developed colorimetric wipe samplers (Direct-Read Wipes for Surface Chemical Detection).
  The project was initiated due to skin and respiratory irritation complaints. The authors performed dermal risk assessment using AIHA’s DRAM Tool and a Bowtie risk assessment methodology.
  DRAM Tool is a very well-established skin risk assessment model. However, it allows for single substances or tasks to be assessed. The proposed Bowtie skin exposure risk assessment methodology allows for multiple substances additive effects evaluation. It is possible to estimate the skin exposure to mixtures using this methodology.
  The authors will present a real-world application of the newly proposed risk summation methodology.

Monday, September 23, 2024 – 3:00 p.m.-3:30 p.m.
Hydrofluoric acid exposure - A study of decontaminating agents against systemic dermal fluoride uptake on an ex vivo human skin model
Presented by Suvarna Mini Vijayan, Friedrich Alexander, Universitat Erlangen - Nurnberg

• Hydrofluoric acid, which is an indispensable chemical in industrial applications poses significant toxicity due to its fluoride ion’s ability to scavenge cations in biological tissues, leading to local acidification by proton released when exposed to the skin. The impact of the concentration and formulations of calcium (Ca2+), magnesium (Mg2+), and aluminium (Al3+) ions as complexing agents on fluoride absorption post hydrofluoric acid exposure via human skin in an ex-vivo diffusion cell model was examined. Moreover, Fluoride absorption was assessed over 6–24 hours, revealing decreased absorption with shorter contamination times. Ca2+ showed slightly greater efficacy than Mg2+. Additionally, using a pH-adjusting buffer enhanced decontamination efficacy. Fluoride-binding agents aid in decontaminating dermal hydrofluoric acid exposure, but prompt decontamination is crucial for minimizing fluoride absorption, making the choice of agent less significant.

Monday, September 23, 2024 – 3:40 p.m.-4:10 p.m.
Advances and Challenges in Skin Decontamination Research
Presented by John Kissel, University of Washington; Howard Maibach, UCSF; Hazem Matar, University of Hertfordshire

• The science behind the implementation of the Mass Casualty decontamination in the USA has been instrumental in developing skin decontamination protocols and procedures. In recent years, a number of advances have been made around the scientific evidence for decontamination of corrosive substances and toxic powders from skin, in particular. Recent research includes using a robotic arm to standardize product application/removal and evaluate the influence of specific types of motions (i.e., blotting, rubbing, or circular motion) on skin decontamination. Skin decontamination is critical in both emergency and routine industrial hygiene practice. Claims of a “wash-in” effect have muddied the discussion of decontamination methodology. The original claim of “wash-in” stems from in vitro experiments, and proponents of the wash-in hypothesis have subsequently sought evidence for wash-in in post-hoc review of existing data, and in conduct of new experiments. What has been demonstrated is that delay of decontamination increases dose. These challenges and others will be discussed in this panel session.

Tuesday, September 24, 2024 – 9:30 a.m.-10:40 a.m.
Panel on sensor technologies for skin monitoring and dermal exposure and risk assessment
Presented by Helen Taylor, PhD, Jennifer Sahmel, PhD, CIH, CSP, FAIHA, Hazem Matar

• This panel will present an overview of the different types of direct reading and sensor technologies currently available to assess skin exposures and skin health. The speakers will address both current technologies and opportunities for future technologies. The speakers will also cover the current data and measurement gaps that can limit the available sensor technologies, and will also address both the value of current technologies in supporting skin health as well as existing challenges in data interpretation and use. The speakers will also address the kinds of data outputs that are needed to improve the efficacy of sensor technologies for dermal exposure and skin health. The session will include an audience discussion to address thoughts about the implementation and use of sensors in the workplace, and will close with a hands-on demonstration session of some of the current instruments and technologies that are available for skin monitoring and measurement.

Tuesday, September 24, 2024 – 10:50 a.m.-11:20 a.m.
Practical approaches to control of dermal exposure
Presented by Helen Taylor, PhD, EnviroDerm

• This presentation aims to first provide some tips and tricks for controlling dermal exposure. There will be examples where, whilst investigating suspected occupational skin problems, tasks were identified where additional controls were needed. Possible practical solutions will be outlined to improve skin exposure control.

Tuesday, September 24, 2024 – 11:30 a.m.-12:00 p.m.
Real-time evaluation of whole-body protective ensembles against chemicals
Presented by Hazem Matar, University of Hertfordshire

• Current testing strategies for the evaluation of personal protective equipment (PPE) ensembles generally adhere to standardised testing regimes. Typically, this involves the assessment of swatches of material (including seals, seams and other closure methods) against a battery of contaminants to determine breakthrough times using diffusion cells. This form of testing is generally regarded as an effective method for selecting appropriate materials and determining material compatibility. Typically, simulants are often used in the evaluation of complete ensembles during the ‘ man-in-simulant test’ (MIST; [1]). Although this testing strategy can assess the protective efficacy of the suit against a simulant, it can be considered to have several drawbacks. The obvious issue is that ensembles worn by human volunteers cannot generally be tested against the toxic chemicals they are designed to protect against. Furthermore, the MIST cannot provide real-time measurements of contaminant ingress. Moreover, the MIST only evaluates the ingress of vapor and so does not consider other likely exposure scenarios which may impact the protective effectiveness of the ensemble, such as direct spray, jet, aerosol, and particulate (e.g. smoke) exposures. Here we report an exposure sensing articulated mannequin (e-SAM) that is capable of the real-time detection of chemicals penetrating a protective ensemble whilst undertaking similar physical movements as the MIST. This is supplemented by a robust and reproducible exposure system and a state-of-the-art exposure chamber to permit the use of any toxic chemical. A unique advantage of this system is the ability to view chemical ingress in real-time and detection of potential ‘bellows’ effect during movement. Additionally, passive absorbent dosimeters (PADs) will be placed on e-SAM in similar locations currently utilized within the MIST. This will enable the bridge to validate the system with the current gold standard test and enable the quantification of total exposure by anatomical region. Based on the outputs from these experiments and once exposures have been established, dermal absorption experiments will be performed using the detected amounts to enable the correlation of sensor and PAD data with skin absorption. The goal of the study is to understand the risks posed to the operator in addition to evaluation of personal protective equipment.

Tuesday, September 24, 2024 – 12:10 a.m.-12:40 p.m.
Practical Considerations and Pitfalls for Using PPE for Skin Protection
Presented by Helen Taylor, PhD, EnviroDerm

• Whilst there is arguably still work to be done on the performance of PPE for skin protection related to permeation and degradation, much work has been undertaken over several decades that has improved our approach and knowledge. However, all this increased knowledge can be easily undermined by a lack of understanding by the end user that results in misuse and increased exposure.
  This presentation will provide some examples where this lack of understanding has led to simple errors being made when using PPE. The examples will look at a variety of aspects that may be under-represented such as storage of PPE, effective education and training, end user understanding of what PPE can and cannot do, and end user understanding of the potential health effects of using PPE.

Tuesday, September 24, 2024 – 9:30 a.m.-10:00 a.m.
Eww, I touched that! A Review of Measured Microbial Dermal Transfer Efficiencies with Guidance on Incorporation into Microbial Risk Assessments
Presented by Heather Avens, PhD, CIH, Insight Exposure and Risk Sciences

• An important parameter in microbial risk assessment (MRA) is understanding how much virus or bacteria transfers to the skin from touching a contaminated surface. We present a review of existing dermal microbial transfer efficiencies, including guidance on how to select an appropriate value for use in a MRA. Based on our review of the available data, there is considerable variability in measured dermal transfer efficiencies, even among microbes of the same type. Thus, caution is necessary when selecting a transfer efficiency value to use in MRA. Though part of the variability is attributable to the nature of biological laboratory methods, many of the dermal transmission factors evaluated were found to impact transfer efficiency. For example, increased pressure, friction, and relative humidity have been reported to enhance microbial transfer.
  
  In contrast, factors that decrease viability, such as drying of the surface or increased time on the surface before contact, led to lower transfer efficiencies. Significant differences were also observed between different types of microbes and different surface materials. If no transfer efficiency data are available for the microbe of concern, data for a microbe with a similar physical structure and similar viability would be the most appropriate selection. To incorporate the variability inherent in the dermal transfer process, it is advisable to use a range of transfer efficiencies. Despite the variability in reported dermal transfer efficiencies, appropriate values can be selected for use in MRA models, through careful consideration of the key factors involved.

Tuesday, September 24, 2024 – 10:10 a.m.-10:40 a.m.
The Human Skin as a Route of Exposure to Biological Aerosols and the Role of Protective Clothing in Preventing Occupational Infectious Disease: Review of the Literature that forms the basis of Healthcare, Laboratory and Industrial Biosafety Practices
Presented by Stephen R. Larson, Tufts University

• This presentation will review the existing scientific literature on the selection and use of protective clothing to prevent skin contact with clouds of aerosolized, airborne infectious agents. Standards, regulations and guidelines for the design, manufacture and use of protective clothing in the healthcare, laboratory and industrial environments will be summarized and evaluated. Clarification of the difference between the need to prevent skin contact with liquid splashes ,sprays and droplets and aerosols will be emphasized. Efforts to quantify the reduction of exposure through the use of suits ,gloves, headgear, respirators and other PPE will be discussed. The health risk of wearing street clothing in workplaces containing clouds of infectious agents will be presented.

Tuesday, September 24, 2024 – 10:50 a.m.-11:20 a.m.
Advanced Harmonization Techniques for Accurate Establishment of In Vitro-In Vivo Drug Permeation Relationships from Dermal Dosage Forms
Presented by Audra Stinchcomb, University of Maryland

• Good correlation has been observed between pharmacokinetic (PK) human dermal absorption studies and in vitro permeation testing (IVPT). Due to the intrinsic variability associated with clinical PK evaluation, the prediction of in vivo exposure from in vitro absorption testing of topical semisolid and liquid dermal products has historically proven difficult. Since drug absorption from complex and unoccluded formulations/exposures can be significantly influenced by environmental factors such as temperature and humidity, maximal effort must be placed on the harmonization of experimental parameters between in vitro and in vivo clinic testing conditions to establish accurate in vitro/in vivo relationships (IVIVR). The goal of the studies was to investigate if increased control over experimental parameters would result in decreased inter-subject variability from common complex dermal formulations or exposure leading to acceptable IVIVR establishment. The low variability in the human PK data presents a proof-of-concept protocol design for testing of complex dermal formulations.

Tuesday, September 24, 2024 – 11:30 a.m.-12:00 p.m.
A Critical Review of Scientific Data Pertaining to Dermal Exposures to Per- and Polyfluorinated Substances (PFAS)
Presented by Shannon Gaffney, PhD, MHS, CIH, FAIHA, Insight Exposure and Risk Sciences

• In the last decade, interest in “per- and polyfluoroalkyl substances (PFAS)” has resulted in the publishing of innumerable peer-reviewed papers addressing different topics related to their persistence and accumulation in the environment and their potential association with adverse health effects in humans. Findings of a few of these publications illustrate that human exposure to PFAS is a complex process occurring through multiple pathways and routes. Despite the vast amount of research that has occurred in recent years, much remains unknown about human exposures to PFAS and any potential associated health risks. One topic that has not been adequately addressed is dermal exposure to PFAS.
  
  For example, chemical and physical properties, exposure conditions, and the integrity of the skin itself all affect the ability of a chemical to be dermally absorbed. The role of these factors and their impact on the importance of dermal exposures to PFAS has not been thoroughly characterized. The objectives of this analysis were to apply a tiered framework to (1) critically review the available scientific data pertaining to human exposures to PFAS via the dermal route and (2) identify critical data gaps. This presentation will provide an overview of the key findings of this review and the strengths and limitations of the available data. Additionally, the overall weight of evidence regarding the role of dermal exposure to PFAS will be discussed.

Tuesday, September 24, 2024 – 12:10 p.m.-12:40 p.m.
Accuracy of professional judgments for dermal exposure assessment using deterministic models
Presented by Jennifer Sahmel, PhD, CIH, CSP, FAIHA, Insight Exposure and Risk Sciences

• The accuracy of professional exposure judgments, particularly for scenarios where only qualitative information is available or a systematic approach is not used, has been evaluated and shown to have a relatively low level of accuracy. In this study, a series of dermal exposure judgments were collected from 90 volunteer U.S. occupational health practitioners in a workshop format to assess the accuracy of their dermal exposure assessment judgments for three specific scenarios. Accuracy was defined as the ability of the participants to identify the correct reference exposure category, as defined by the quantitative exposure banding categories utilized by the American Industrial Hygiene Association (AIHA). The participants received progressively detailed training regarding dermal exposure assessments and scenario-specific information during the workshop, and the relative accuracy of their category judgments over time was compared. The results of the study indicated that despite substantial education and training in exposure assessment generally, the practitioners had very little experience in performing dermal exposure assessments and a low level of comfort and initial accuracy in performing these assessments. Participants were generally able to identify the reference or “true” category of dermal exposure acceptability when provided with relevant, scenario-specific surface-loading data for use in the assessment process. As a result, a closer analysis of default loading values used in dermal exposure assessments to evaluate their accuracy relative to real-world or measured dermal loading values is needed, along with consistent improvements in training and the dermal models used in exposure and risk assessment.

Tuesday, September 24, 2024 – 3:30 p.m.-4:00 p.m.
Exploring Skin Absorption and Retention of Bisphenol S (BPS): Implications for Occupational Exposure and Health Risks
Presented by Fabrice Marquet, French National Research and Safety Institute for the Prevention of Occupational Accidents and Diseases (INRS)

• National Research and Safety Institute for the Prevention of Occupational Accidents and Diseases (INRS)
  Bisphenol S (BPS), a substitute for Bisphenol A (BPA), exhibits adverse effects on reproduction, mammary glands, metabolism, and elevates cancer and cardiovascular risks. Skin absorption, which is prevalent in thermal paper handling, is investigated in vitro using Franz-type cells with human and rat skin, and in vivo in rats, following OECD guidelines.
  In vitro experiments, utilizing three vehicles to simulate different exposure scenarios, reveal persistent cutaneous absorption of BPS in human beyond skin washout from the skin reservoir (30-60% of the deposited dose). When the deposition zone is occluded, the absorption flux of BPS, solubilized in water or acetone, increases by a factor of 4 to 6.
  
  In vivo, after intravenous administration (reference route), BPS is rapidly metabolized and is eliminated primarily in urine as glucuronide and sulfate conjugates. After continuous cutaneous exposure (8 or 24 h), nearly half of the deposited BPS persists in the skin, with major elimination through urine (60-70%) as BPS-glucuronide, peaking between 8 and 24 hours.
  The study emphasizes significant post-exposure skin retention, especially in the stratum corneum, acting as a reservoir for continuous BPS diffusion post-cleansing. Occlusion, such as wearing gloves on previously exposed skin, enhances BPS percutaneous absorption. Occupational risk assessments must consider these factors to avoid underestimating exposure.

Tuesday, September 24, 2024 – 4:10 p.m.-4:40 p.m.
Complexities of Percutaneous Penetration
Presented by Howard Maibach, PhD, UCSF

• The last half century has yielded a vast mass of data on percutaneous penetration. This presentation brings into context the many steps involved and how to clinically interpret same.

Tuesday, September 24, 2024 – 3:30 p.m.-4:00 p.m.
Potential inadequacy of inhalation only risk assessments and respiratory protection recommendations due to dermal uptake of vapor phase chemicals
Presented by John C. Kissel, PhD, University of Washington

• Empirical measurements suggesting direct dermal absorption of chemicals from contaminated air date to at least the early 1960’s. Those early measurements were collected by researchers focused on occupational exposures. Mathematical modeling of this phenomenon lagged empirical observation. A seminal paper by Weschler and Nazaroff (2014) provided a theoretical basis and method for estimation of the contribution of direct dermal uptake from vapor. However, those authors were focused on exposures to chemicals in residential air and showed calculations for organic compounds identified in residential air sampling and at corresponding air concentration levels.
  
  We review the prior occupational studies and evaluate the predictive ability of a modified version of the Weschler-Nazaroff protocol. Because risk evaluation of contaminated air based on inhalation dose alone may underestimate dose and because efficacy of standard respiratory protection declines as the contribution of direct uptake from vapor increases, it is important for industrial hygienists to understand basic concepts governing dermal absorption from vapor.

Tuesday, September 24, 2024 – 4:10 p.m.-4:40 p.m.
Using results of in vitro skin permeation experiments to predict in vivo chemical absorption into skin
Presented by Annette Bunge, Colorado School of Mines

• Assessing the potential health risk from skin exposures to chemicals is important for identifying scenarios in which skin protection is needed for safe work. These assessments are frequently based on ‘in vitro’ measurements of chemical absorption into and through excised skin from humans, or equations predicting dermal absorption based on large data sets of human in vitro measurements for other chemicals. A substantial literature has demonstrated good correlation between in vitro and in vivo dermal absorption measurements for a large range of chemicals, and identified situations in which correlation are likely to be poor. Nevertheless, there are those who question the extent to which in vitro measurements, or equations derived from them, mimic skin on the human body. A few recent publications claim that dermal absorption calculations using the popular Potts-Guy equation, which was derived from steady-state human skin permeability coefficients from water, diverge widely from human in vivo observations. This presentation will describe in vitro skin absorption experiments, provide comparisons with in vivo measurements, and discuss the appropriate use of predictive equations derived from in vitro skin absorption experiments. Claims that these predictive equations significantly diverge from in vivo observations will be examined and likely causes for these findings explored.

Tuesday, September 24, 2024 – 4:50 p.m.-5:20 p.m.
Overview of Dermal Uptake Modeling using AIHA’s IH SkinPerm Tool
Presented by Josh Maskrey, Insight Exposure and Risk Sciences

• Dermal exposure and uptake modeling is a critical skill for practicing OEHS professionals. This presentation will provide attendees with a brief, practical overview of dermal exposure modeling approaches available in the AIHA’s IH SkinPerm modeling package, which is a free modeling tool. The session is intended to provide exposure and risk assessors with a working knowledge of the tool, the ability to explain the uptake modeling capabilities of the tool, and a basic overview of the theoretical basis of the tool. This session includes an overview of the four types of dermal uptake models available in IH SkinPerm including 1) instantaneous deposition, 2) deposition over time, 3) vapor absorption and 4) absorption from an aqueous solution. A practical treatment of the inputs and research required to effectively use the tool will be provided along with a brief explanation of the modeling theory used in the uptake models. The assumptions and limitations inherent to the modeling theory used in the tool will be explained. A use case involving dermal uptake of a semi-volatile chemical splashed on the skin will be used to provide an example of well-designed inputs and an explanation of the results panel in IH SkinPerm.

Wednesday, September 25, 2024 – 9:30 a.m.-10:00 a.m.
Hazard characterization of dermal exposure to Toluene Diisocyanate (TDI)
Presented by Naomi Hudson, PhD, NIOSH

• Toluene diisocyanate (TD) is used in a variety of materials including flexible foam, elastomers, coatings, sealants, and binders. Other uses for TDI include the manufacture of fibers, paints and varnishes, insulation materials for buildings, and in shoe soles. An estimated 991,680 workers are potentially exposed to TDI. Workers exposed to TDI are at risk of respiratory impairment including occupational asthma. Other health effects include irritation to the skin, eyes, and respiratory tract as well as respiratory and dermal sensitization. Animal studies demonstrated the ability of TDI to induce Type IV Hypersensitivity responses in the skin and acute contact dermatitis (ACD). In humans, reports of skin problems, including irritation and ACD have been documented after exposure to TDI.
  
  The presence of ACD indicates that TDI has potential for skin sensitization and is supported by positive reactions to skin prick tests and patch tests using 0.1% TDI. The primary routes of exposure for TDI include inhalation, dermal absorption, eye absorption, and ingestion. Depending on how it is used, non-polymerized TDI may be present in air as vapor, aerosol, and/or dust. In addition to the pulmonary deposition of aerosols or dust, TDI can contaminate skin by directly touching TDI or TDI-contaminated items such as work surfaces or equipment. Studies suggest that a small percentage of TDI on skin will be absorbed into the body and could lead to respiratory sensitization.

Wednesday, September 25, 2024 – 10:10 a.m.-10:40 a.m.
Measuring phthalate exposure using sebum oil in artificial sweat and correlation to attention deficit
Presented by Bruce Calder, Claigan Environmental

• Phthalates, such as Di(2-ethylhexyl)phthalate (DEHP), are one of the potential leading causes of attention deficit and autism. Human exposure is through a simple mechanism of hand transfer from everyday products to oral ingestion. With the DEHP / attention deficit mechanism well understood, DEHP exposure from common components such as power cords, tool bags, and safety equipment presents a significant risk. However, DEHP is non-polar and is not released from products using simple NIOSH tests with distilled water. DEHP exposure require human sweat oil stimulants added to the water wipe test. This presentation will show how to measure DEHP exposure through a combined polar (distilled water) and non-polar (sebum oil) simulation of human sweat. The exposure measurement will simulate hand contact of the product based on NIOSH 9100. Standard calculations for oral ingestion based on hand-to-mouth action will be used to estimate human ingestion dosage. Further discussion will be including showing the DEHP attention deficit mechanism with relation to the average DEHP exposure dosages measured from common products and tools. The presentation will include visual examples to enable participants to better internalize the impact and methods.

Wednesday, September 25, 2024 – 9:30 a.m.-10:00 a.m.
The Mismeasure of Acute Dermal Toxicity
Presented by John Kissel, PhD, University of Washington

• It is well established that the practice of describing dermal absorption of chemicals as a fixed fraction of the surface load is grounded in bad physics. Fractional absorption varies with skin load and is not a fixed property of the chemical. This issue is routinely encountered in regulatory strategies involving evaluation of risks of dermal exposure to chemical compounds. The same problem also applies in standardized dermal toxicity testing. Rodents used in laboratory experiments have limited available surface area for absorption, which may be further restricted by practicalities (e.g., retention of liquids). For compounds that are not rapidly absorbed, demonstration of low toxicity (e.g., LD50 > 5000 mg/kg) may not actually be experimentally feasible. However, values of Nderm (the non-dimensional metric describing the ratio of supply to expected loss mechanisms) are very seldom reported with dermal toxicity test results. Indeed, sufficient experimental detail to even permit calculation of Nderm is routinely absent in publicly accessible regulatory documents in the U.S. as those details are treated as confidential business information (CBI). Consequently, many tabulated dermal toxicity values are meaningless. Furthermore, use of laboratory animals in experiments that are so poorly designed that useful information cannot be extracted constitutes laboratory animal abuse.

Wednesday, September 25, 2024 – 10:10 a.m.-10:40 a.m.
Panel discussion - Emerging Topics in Dermal Exposure and Risk Assessment
Moderator: Jennifer Sahmel, Insight Exposure and Risk Sciences

Tuesday, September 24, 12:40 p.m.-2:00 p.m.

Analytical Method Validation Study of 1,2-Dichloropropane on Charcoal-Based Dermal Collection Patches
Presented by Heather N. Lynch, Integral Consulting

Application of New Custom-Made Activated Charcoal Cloth Patch in Different Real Work Conditions
Presented by Rani Claus, KU Leuven

Assessment of Surfaces Contamination and Dermal Exposure to 5-Fluorouracil in Healthcare Settings
Presented by Jeroen Vanoirbeek, University of Leuven

Dermal Exposure of Additive Manufacturing Operators During Ceramic-Based Vat Photopolymerization
Presented by Marelizé van Ree, Occupational Hygiene and Health Research Initiative (OHHRI), North-West University, South Africa

Dermal Permeation of Polyfluoroalkyl Substances from Textile Vehicles Using Alternative Skin Models
Presented by Andrew Hall, North Carolina State University

Dermal Wipe Sampling Method Development and Validation for Semi-Volatile and Non-Volatile Flame-Retardant Compounds TBBPA and TPP for Use in Occupational Exposure Assessments
Presented by Lauren Gloekler, Stantec ChemRisk

Evaluation of Dermal Absorption of Welding Fume Components by Elemental Imaging
Presented by Makiko Iwase, National Institute of Occupational Safety and Health, Japan

Exploring Occupational Irritant Hand Dermatitis Amongst Healthcare workers in NHS Grampian
Presented by Dr. Zoi Papadatou, Robert Gordon Univeristy

Exposure Assessment of Polycyclic Aromatic Hydrocarbons in Refined Coal
Presented by Seth McCormick, NIOSH

Hand Dermatitis Prevalence and Severity in a Population of South African Nursing Students
Presented by Johan Du Plessis, North-West University

Health Risk Assessment of Dermal Exposure to Heavy Metal Dust in Nail Salon Technicians
Presented by Zohreh Mohebian, PhD, Isfahan University of Medical Sciences, Isfahan, Iran

Manuals Selecting Chemical Protective Gloves and Respiratory Protective Equipment for the Construction Industry
Presented by Mariko Ono-Ogasawara, PhD, Japan National Institute of Occupational Safety and Health (JNIOSH)

Potential Inadequacy of Inhalation Only Risk Assessments and Respiratory Protection Recommendations Due to Dermal Uptake of Vapor Phase Chemicals; Supplemental Material: Literature Review
Presented by John C. Kissel, PhD, University of Washington

What do ACGIH Members Know about Occupational Skin Exposures?
Presented by Leena Nylander-French, PhD, ACGIH Biological Exposure Indices Committee

Model Predictions of MeS Skin Exposure Informed by the Variability of Metabolite Urinary Excretion in Controlled Human Exposures
Presented by Leena Nylander-French, PhD, ACGIH Biological Exposure Indices Committee

Development of a skin dosing method using Methyl Salicylate
Presented by Leena Nylander-French, PhD, ACGIH Biological Exposure Indices Committee