Estimation of volatile organic compound exposure concentrations and time to reach a specific dermal absorption using physiologically based pharmacokinetic modeling

A procedure was proposed to estimate dermal exposures based on a physiologically based pharmacokinetic (PBPK) model developed in rats. The study examined vapor concentrations ranging from 500 to 10,000 ppm for dibromomethane and 2,500 to 40,000 ppm for bromochloromethane. These concentrations were reconstructed based on chemical blood levels measured in 4 hr, with errors varying from 0.0% to 52.0%. The PBPK approach adequately predicted the blood concentrations and helped simulate contaminant transport through the stratum corneum and distribution in the body compartments. The proposed technique made it possible to estimate the skin absorption time (SAT) obtained from acute inhalation toxicity data. An inverse relationship exists between the SAT and exposure concentration. The method can be helpful in toxicology and risk assessment of hazardous volatile organic compounds.

UV-A Radiation: Safe Human Exposure and Antibacterial Activity

UV radiation is used for sterilization but has adverse health effects in humans. UV-A radiation has lower antimicrobial effect than UV-B and UV-C but constitutes a lower health risk, opening up the possibility to sanitize environments with human presence in controlled exposure conditions. We investigated this possibility by identifying safe exposure conditions to a UV-A lamp along with efficient sanitization of the environment. The human exposure limits were calculated following the guidelines provided by the International Commission on Non-Ionizing Radiation Protection and the International Commission on Illumination. Antibacterial activity was evaluated on Escherichia coli, Pseudomonas aeruginosa and Staphylococcus aureus. The maximum human exposure duration has been identified at different irradiation distance and angle, increasing with the increase of both parameters. Bactericidal activity was observed in all microorganisms and was higher with higher exposure time and at lower distance from the source. Noteworthily, in equal conditions of radiant exposure, the exposure time impacts on the bactericidal activity more than the distance from the source. The modulation of factors such as distance from the source, exposure time and irradiation angle can enable effective antibacterial activity and human safety. Prolonged direct irradiation of the surfaces associated with indirect human exposure represents the condition of greater efficacy and safety.

A method to assess dermal absorption dynamics of chemical warfare agents: Finite doses of volatile compounds

Chemical warfare agents are absorbed into the body from various entry routes and may have detrimental effects on human health. As many chemical compounds in this group are lipophilic, the outer layer of the skin is at an elevated risk. This contribution explores the dynamics of skin penetration for risk assessment. A previously validated model was applied to describe how an agent is transported across the stratum corneum following dermal exposure to a finite dose of a chemical. A mathematical construct was implemented for estimating the time constants and the cumulative amount of permeant entering the bloodstream or being released into the environment. Empirical equations were selected to determine the ratio of the steady-state evaporation rate to the steady-state dermal absorption rate and the physicochemical properties of the chemical warfare agents. Wolfram Mathematica was employed to run the simulations. The results from the newly derived expressions for the time constants matched those directly obtained from the validated model. For example, sarin gas had steady-state evaporation to an absorption rate of 991.25, and a total fractional absorption and evaporation of 5.1% and 94.9%, respectively. Combined with occupational exposure limits, the findings can help researchers assess an individual's risk level and develop protection programs.

Assessment of personal inhalation and skin exposures to polymeric methylene diphenyl diisocyanate during polyurethane fabric coating

Methylene diphenyl diisocyanate (MDI) monomers and polymeric MDI (pMDI) are aromatic isocyanates widely used in the production of polyurethanes. These isocyanates can cause occupational asthma, hypersensitivity pneumonitis, as well as contact dermatitis. Skin exposure likely contributes toward initial sensitization but is challenging to monitor and quantitate. In this work, we characterized workers' personal inhalation and skin exposures to pMDI in a polyurethane fabric coating factory for subsequent health effect studies. Full-shift personal and area air samples were collected from eleven workers in representative job areas daily for 1-2 weeks. Skin exposure to hands was evaluated concomitantly with a newly developed reagent-impregnated cotton glove dosimeter. Samples were analyzed for pMDI by liquid chromatography-tandem mass spectrometry. In personal airborne samples, the concentration of 4,4^'-MDI isomer, expressed as total NCO, had a geometric mean (GM) and geometric standard deviation (GSD) of 5.1 and 3.3 ng NCO/m³, respectively (range: 0.5-1862 ng NCO/m³). Other MDI isomers were found at much lower concentrations. Analysis of 4,4^'-MDI in the glove dosimeters exhibited much greater exposures (GM: 10 ng/cm²) and substantial variability (GSD: 20 ng NCO/cm²; range: 0-295 ng NCO/cm²). MDI inhalation exposure was well below occupational limits for MDI for all the job areas. However, MDI skin exposure to hands was substantial. These findings demonstrated the potential for substantial isocyanate skin exposure in work settings with very low airborne levels. This exposure characterization should inform future studies that aim to assess the health effects of work exposures to MDI and the effectiveness of protective measures.

A systematic review: metabolomics-based identification of altered metabolites and pathways in the skin caused by internal and external factors

The skin's ability to function optimally is affected by many diverse factors. Metabolomics has a great potential to improve our understanding of the underlying metabolic changes and the affected pathways. Therefore, the objective of this study was to review the current state of the literature and to perform further metabolic pathway analysis on the obtained data. The aim was to gain an overview of the metabolic changes under altered conditions and to identify common and different patterns as a function of the investigated factors. A cross-study comparison of the extracted studies from different databases identified 364 metabolites, whose concentrations were considerably altered by the following factor groups: irradiation, xenobiotics, aging, and skin diseases (mainly psoriasis). Using metabolic databases and pathway analysis tools the individual metabolites were assigned to the corresponding metabolic pathways and the most strongly affected signaling pathways were identified. All factors induced oxidative stress. Thus, antioxidant defense systems, especially coenzyme Q₁₀  (aging) and the glutathione system (irradiation, aging, xenobiotics) were impacted. Lipid metabolism was also impacted by all factors studied. The carnitine shuttle as part of β-oxidation was activated by all factor groups except aging. Glycolysis, Krebs (TCA) cycle and purine metabolism were mainly affected by irradiation and xenobiotics. The pentose phosphate pathway was activated and Krebs cycle was downregulated in response to oxidative stress. In summary, it can be ascertained that mainly energy metabolism, lipid metabolism, antioxidative defense and DNA repair systems were impacted by the factors studied.

Quantitative skin exposure assessment of metals: A case study

This article provides guidance into the quantitative risk assessment of skin exposures to metals. The use of wipe sampling methodologies has been shown to be standardised and effective for skin exposure assessment to metals. However, there is a lack of guidance documents and frameworks available to evaluate the level of health risk to workers from skin exposures to metals. Adverse health effects from exposures to metals have been described in the literature (Fernández-Nieto et al. 2006; Herman et al. 2006; Kreiss et al. 1996). Monitoring of workplace exposures typically focuses on the assessment of respiratory exposures. To provide a safe workplace there is a need to ensure all routes of exposure are risk assessed and controlled. The goal of this article was to develop skin (surface) exposure limits to metals, using the construction industry as a test environment, to quantitatively assess worker health risk of skin exposures to metals. This research concluded it was not feasible to establish single quantitative skin exposure limits to metals due to the many assumptions surrounding dermal exposures. A range of acceptable exposure limits are presented.

Safety Assessment of Polypyrrole Nanoparticles and Spray-Coated Textiles

Polypyrrole (PPy) nanoparticles (NPs) are used for the coating of materials, such as textiles, with biomedical applications, including wound care and tissue engineering, but they are also promising antibacterial agents. In this work, PPy NPs were used for the spray-coating of textiles with antimicrobial properties. The functional properties of the materials were verified, and their safety was evaluated. Two main exposure scenarios for humans were identified: inhalation of PPy NPs during spray (manufacturing) and direct skin contact with NPs-coated fabrics (use). Thus, the toxicity properties of PPy NPs and PPy-coated textiles were assessed by using in vitro models representative of the lung and the skin. The results from the materials' characterization showed the stability of both the PPy NP suspension and the textile coating, even after washing cycles and extraction in artificial sweat. Data from an in vitro model of the air-blood barrier showed the low toxicity of these NPs, with no alteration of cell viability and functionality observed. The skin toxicity of PPy NPs and the coated textiles was assessed on a reconstructed human epidermis model following OECD 431 and 439 guidelines. PPy NPs proved to be non-corrosive at the tested conditions, as well as non-irritant after extraction in artificial sweat at two different pH conditions. The obtained data suggest that PPy NPs are safe NMs in applications for textile coating.

Skin Exposure to Acrylates in Nail Salons

OBJECTIVES

The nail salon industry has seen significant growth in recent years. Nail technicians provide manicures, pedicures and apply artificial nails; tasks that expose them to chemicals, including acrylates that are known skin and respiratory sensitizers. This paper reports on potential skin exposure to acrylates among nail technicians in Toronto, Canada.

METHODS

Hand skin wipes were collected after (i) the application of artificial nails, (ii) the application of ultraviolet cured gel nail polish, and (iii) deliberate contact with nail polish. Surface wipes were collected from work areas and surfaces contaminated with known products. Wipe samples were analysed for eight acrylates: methyl acrylate (MA), ethyl acrylate (EA), methyl methacrylate (MMA), ethyl methacrylate (EMA), 2-hydroxyethyl acrylate (HEA), 2-hydroxyethyl methacrylate (HEMA), 2-hydroxypropyl methacrylate (HPMA), and ethylene glycol dimethacrylate (EGDMA) by gas chromatography with mass spectrometry.

RESULTS

Thirty-five wipe samples were collected. No acrylates were detected in skin samples (n = 8) or work surfaces (n = 6). However, MMA, EMA, EA, HEMA, and HPMA were detected in the samples of surfaces contaminated with known products. MMA was detected in 28% of products tested. HEMA and HPMA were detected where deliberate contact with nail polish occurred.

CONCLUSIONS

These results confirm that acrylates are present in nail products. However, no acrylates were detected in skin wipes. MMA, a chemical prohibited for use in cosmetics in Canada, was detected in nail polishes. Nail technicians should continue to employ safe work practices that reduce the probability of skin contact with acrylates and other chemicals.

A Total Worker Health Approach to Skin Exposure Assessment: Experiences from the Firefighter Cancer Initiative

Increasing scientific evidence suggests that addressing complex, wide-ranging concerns among worker populations should include the integration of traditional occupational safety and health with often siloed worksite wellness programs. The Total Worker Health (TWH) approach developed by the National Institute for Occupational Safety and Health can support skin cancer prevention efforts by integrating organizational-level policies, programs, and practices that strategically merge both skin protection from work-related safety and health hazards with promotion of skin illness prevention efforts. In the firefighter workforce, epidemiologic studies suggest an increased risk of skin cancer despite the use of personal protective equipment during fire incident response. Mechanisms for dermal absorption of carcinogenic compounds such as polycyclic aromatic hydrocarbons have given insight into how these hazardous chemicals can enter the skin and increase cancer risk. Mitigation of carcinogenic exposures requires a TWH approach that merges skin protection and promotion, routine surveillance, skin health assessment, worksite-based interventions, and regular evaluation of program activities. In this commentary, an example of a TWH approach is provided from the Firefighter Cancer Initiative (FCI), a transdisciplinary initiative focused at addressing excess burden of cancer in the firefighter workforce. The FCI builds on the TWH approach through the following components: (i) organizational leadership commitment; (ii) elimination of workplace hazards and promotion of worker well-being; (iii) engagement of workers in program design and delivery; (iv) ensuring confidentiality and privacy in program participation; and (v) integrating systems effectively. Occupational hygienists have strong potential to play a crucial role beyond traditional risk assessment, exposure assessment, and health protection that further includes skin health promotion and integration of related programs into a TWH framework.

Cobalt exposure via skin alters lung immune cells and enhances pulmonary responses to cobalt in mice

Cobalt has been associated with allergic contact dermatitis and occupational asthma. However, the link between skin exposure and lung responses to cobalt is currently unknown. We investigated the effect of prior dermal sensitization to cobalt on pulmonary physiological and immunological responses after subsequent challenge with cobalt via the airways. BALB/c mice received epicutaneous applications (25 μL/ear) with 5% CoCl_2*6H₂O (Co) or the vehicle (Veh) dimethyl sulfoxide (DMSO) twice; they then received oropharyngeal challenges with 0.05% CoCl_2*6H₂O or saline five times, thereby obtaining four groups: Veh/Veh, Co/Veh, Veh/Co, and Co/Co. To detect early respiratory responses noninvasively, we performed sequential in vivo microcomputed tomography (µCT). One day after the last challenge, we assessed airway hyperreactivity (AHR) to methacholine, inflammation in bronchoalveolar lavage (BAL), innate lymphoid cells (ILCs) and dendritic cells (DCs) in the lungs, and serum IgE. Compared with the Veh/Veh group, the Co/Co group showed increased µCT-derived lung response, increased AHR to methacholine, mixed neutrophilic and eosinophilic inflammation, elevated monocyte chemoattractant protein-1 (MCP-1), and elevated keratinocyte chemoattractant (KC) in BAL. Flow cytometry in the Co/Co group demonstrated increased DC, type 1 and type 2 conventional DC (cDC1/cDC2), monocyte-derived DC, increased ILC group 2, and natural cytotoxicity receptor^-ILC group 3. The Veh/Co group showed only increased AHR to methacholine and elevated MCP-1 in BAL, whereas the Co/Veh group showed increased cDC1 and ILC2 in lung. We conclude that dermal sensitization to cobalt may increase the susceptibility of the lungs to inhaling cobalt. Mechanistically, this enhanced susceptibility involves changes in pulmonary DCs and ILCs.

Associations of Metrics of Peak Inhalation Exposure and Skin Exposure Indices With Beryllium Sensitization at a Beryllium Manufacturing Facility

OBJECTIVES

Peak beryllium inhalation exposures and exposure to the skin may be relevant for developing beryllium sensitization (BeS). The objective of this study was to identify risk factors associated with BeS to inform the prevention of sensitization, and the development of chronic beryllium disease (CBD).

METHODS

In a survey of short-term workers employed at a primary beryllium manufacturing facility between the years 1994-1999, 264 participants completed a questionnaire and were tested for BeS. A range of qualitative and quantitative peak inhalation metrics and skin exposure indices were created using: personal full-shift beryllium exposure measurements, 15 min to 24 h process-specific task and area exposure measurements, glove measurements as indicator of skin exposure, process-upset information gleaned from historical reports, and self-reported information on exposure events. Hierarchical clustering was conducted to systematically group participants based on similarity of patterns of 16 exposure variables. The associations of the exposure metrics with BeS and self-reported skin symptoms (in work areas processing beryllium salts as well as in other work areas) were evaluated using correlation analysis, log-binomial and logistic regression models with splines.

RESULTS

Metrics of peak inhalation exposure, indices of skin exposure, and using material containing beryllium salts were significantly associated with skin symptoms and BeS; skin symptoms were a strong predictor of BeS. However, in this cohort, we could not tease apart the independent effects of skin exposure from inhalation exposure, as these exposures occurred simultaneously and were highly correlated. Hierarchical clustering identified groups of participants with unique patterns of exposure characteristics resulting in different prevalence of BeS and skin symptoms. A cluster with high skin exposure index and use of material containing beryllium salts had the highest prevalence of BeS and self-reported skin symptoms, followed by a cluster with high inhalation and skin exposure index and a very small fraction of jobs in which beryllium salts were used. A cluster with low inhalation and skin exposure and no workers using beryllium salts had no cases of BeS.

CONCLUSION

Multiple pathways and types of exposure were associated with BeS and may be important for informing BeS prevention. Prevention efforts should focus on controlling airborne beryllium exposures with attention to peaks, use of process characteristics (e.g. the likelihood of upset conditions to design interventions) minimize skin exposure to beryllium particles, and in particular, eliminate skin contact with beryllium salts to interrupt potential exposure pathways for BeS risk.

The Usefulness of Straight Chemotherapy for Dermal Exposed Anaplastic Lymphoma Kinase Fusion-Positive Anaplastic Large-Cell Lymphoma with Intracranial Invasion

Anaplastic large-cell lymphoma (ALCL) is characterized as extranodal lymphoma and usually chemosensitive disease with overall survival rate of 70%–90%. Prognosis is roughly distinguished by the existence of anaplastic lymphoma kinase (ALK) fusion in tumor cells with higher frequencies observed in the pediatric population, and the outcome of ALK fusion-positive ALCL is relatively good when appropriate treatment is completed. Here, we report a case of dermal-exposed ALK fusion-positive ALCL with intracranial invasion. The patient received straight chemotherapy (ALCL99 protocol) without any plastic or resection surgery. The dermal dehiscence was rapidly healed with controllable local infection, and the tumor was regressed without relapse. Therefore, straight chemotherapy has clinical relevance and is a useful treatment strategy for ALK fusion-positive ALCL with dermal dehiscence.

Development of a Series of Fluorescent Probes for the Early Diagnostic Imaging of Sulfur Mustard Poisoning

Sulfur mustard is one of the most harmful chemical warfare agents and can induce skin, eye, and lung injuries. However, it is hard for medical stuff to diagnose sulfur mustard poisoning early because of the incubation period after sulfur mustard exposure. Detecting intact sulfur mustard in vivo might be an effective approach for the early diagnosis of sulfur mustard poisoning. A series of fluorescent probes for intact sulfur mustard detection were developed in this study. All of the developed probes could react with sulfur mustard selectivity. Among these probes, SiNIR-SM exhibited an extremely good response rate and a high off/on contrast. To the best of our knowledge, SiNIR-SM is the first near-infrared fluorescent probe for the sulfur mustard detection. Both SiNIR-SM and OxSM-1 were successfully applied to image sulfur mustard in living cells. Using SiNIR-SM, we found that sulfur mustard accumulates in the mitochondria of living cells. This result could provide a new insight for the treatment of sulfur mustard injuries. We also found that SiNIR-SM is suitable for the early diagnostic imaging of sulfur mustard poisoning in SKH-1 mice via the detection of intact sulfur mustard.

Skin exposure to the rubber accelerator diphenylguanidine in medical gloves-An experimental study

BACKGROUND

Dermatitis caused by occupational contact allergy to rubber additives such as diphenylguanidine (DPG) in medical gloves is a hazard for healthcare workers. Both the duration of exposure to medical gloves and the number of gloves used per day vary. The use of alcoholic skin disinfectants before glove donning is mandatory.

OBJECTIVES

To assess whether skin exposure to the rubber accelerator DPG released from glove material is influenced by alcoholic hand disinfectants, time, and pH.

METHODS

With the use of ethanol washes, the amount of DPG left on the hands after wearing of gloves for 60 minutes was measured, and comparisons between hands exposed and not exposed to alcoholic disinfectant before glove donning were made. With the use of artificial sweat buffered at pH 4, 5, and 6, DPG release from the insides of gloves at different times was measured.

RESULTS

The use of alcoholic disinfectant prior to polyisoprene glove donning increased the amount of DPG recovered from the hands. Of the DPG released from polyisoprene gloves into artificial sweat, almost 84% was released within 10 minutes. pH did not influence the rate of release.

CONCLUSIONS

The use of alcoholic disinfectant increased skin exposure to the rubber accelerator DPG. Even a short duration of use of gloves results in substantial exposure to DPG.

Skin exposure to epoxy chemicals in construction coating, assessed by observation, interviews, and measurements

BACKGROUND

Epoxy resin systems (ERSs) are among the leading causes of occupational allergic contact dermatitis.

OBJECTIVES

To identify riskful exposures and sources of skin exposure, and to quantify skin exposure to diglycidyl ether of bisphenol A (DGEBA) epoxy monomer, in construction coating work.

METHODS

Skin exposure to epoxy chemicals was studied in 5 coating companies through (a) interviews and visual observation, (b) quantifying DGEBA on 12 workers' skin by tape-stripping, (c) measuring DGEBA on 23 surfaces by wipe-sampling, and (d) quantifying DGEBA in new sewage pipe. Acetone extracts of the tapes, wipes and sawdust from a newly hardened sewage pipe were analysed by gas chromatography/mass spectrometry.

RESULTS

Identified riskful exposures were, for example, mixing ERSs, handling coating pots, and working above shoulder level. Epoxy stains on, for example, tools, equipment and clothing were seen in all workplaces. Protective gloves were of varying quality, and were not always suitable for chemicals. The amount of DGEBA on the workers' skin varied considerably. All screened tool handles were contaminated. Two-day-old epoxy sewage pipe contained 3.2% DGEBA.

CONCLUSIONS

Construction coating entails skin contact with ERSs directly and via contaminated surfaces, personal protective equipment, and recently hardened epoxy materials. Observation is a useful method for assessing skin exposure in coating work.

Neglected exposure route: cobalt on skin and its associations with urinary cobalt levels

OBJECTIVES

Cobalt (Co) exposure is associated with adverse health effects including skin sensitisation, asthma and interstitial lung fibrosis. Exposure to Co in industrial settings is often assessed using air samples or biomonitoring in urine. Skin exposure is rarely measured. Aim of this study was to quantify and compare the importance of Co skin exposure and respiratory exposure in determining urinary Co concentrations.

METHODS

Co skin exposure was measured in 76 hard metal workers by acid wipe sampling before and at the end of work shifts. Spot urine was collected during a 24-hour period from the start of a shift. Respiratory exposure was measured by personal inhalable dust sampling during a shift in 30 workers. Co was analysed by inductively coupled plasma mass spectrometry.

RESULTS

Quantile regression modelling showed that a doubling of Co on skin before or at the end of shift increased the median urinary concentration of Co by 70% (p<0.001) or 32% (p<0.001), respectively. A doubling of Co in air increased median urinary Co by 38% (p<0.001). Co skin exposures were still significantly associated with urinary Co after excluding a group of workers with high respiratory exposure (33%, p=0.021 and 17%, p=0.002).

CONCLUSIONS

The results indicate an association between Co skin exposure and urinary Co concentrations. This should be considered when using urinary Co as a biomarker of exposure.

Biological monitoring of dermal and air exposure to cobalt at a Swedish hard metal production plant: does dermal exposure contribute to uptake?

BACKGROUND

Occupational exposure to cobalt is well established in hard metal manufacture. Cobalt is known to cause contact allergy, asthma, hard metal lung disease, and lung cancer. The relationship between skin exposure and uptake determined in blood has not been extensively investigated.

OBJECTIVE

To examine whether skin and inhalable air exposure to cobalt contributes to uptake, determined as cobalt in blood, in a hard metal manufacturing factory.

METHODS

The amount of cobalt on the skin found with an acid wash technique, the air concentrations of inhalable cobalt and cobalt blood concentrations were determined and correlated in exposed workers.

RESULTS

We found a significant rank correlation for cobalt concentrations on the skin, in inhalable air, and in blood (0.376-0.498). Multiple linear regression showed significant regression coefficients for cobalt skin exposure and blood (B = 0.01, p < 0.05) and for inhalable cobalt in air and blood (B = 49.1, p < 0.001). According to our model based on data from the regression analyses, a twofold increase in skin exposure levels at different air concentrations caused a 3-14% increase in blood levels.

CONCLUSIONS

Our data suggest that skin exposure to cobalt in the hard metal industry could affect the total uptake at the same order of magnitude as air exposure.

Assessment of exposure to pesticides during mixing/loading and spraying of tomatoes in the open field

Some evidence of exposure-response of metolachlor and pendimethalin for lung cancer and an association of metribuzin with risk of glioma have been reported. The primary objectives in this study were to evaluate exposure and occupational risk during mixing/loading of pesticides and during their application to tomatoes cultivated in open fields. Sixteen farmers were sampled. Respiratory exposure was estimated by personal air sampling using fiberglass filters in a IOM device. Dermal exposure was assessed using skin pads and hand washing. Absorbed doses were estimated assuming 100% lung retention, and 50% or 10% skin absorption for metribuzin, and pendimethalin and metolachlor, respectively. The three pesticides were quantified by gas chromatography tandem mass spectrometry in all matrices. Metolachlor was used as a tracer of contamination of clothes and tractors unrelated to the exposure monitored. Respiratory exposure to metribuzin, used in granular form, was on average more than one order of magnitude higher than exposure to pendimethalin, used in the form of microencapsulated liquid. The actual doses were 0.067-8.08 µg/kg bw, 0.420-12.6 µg/kg bw, and 0.003-0.877 µg/kg bw for pendimethalin, metribuzin, and metolachlor, respectively. Dermal exposure was about 88% of the actual dose for metribuzin and more than 95%, for pendimethalin and metolachlor. For risk assessment, the total absorbed doses (sum of respiratory and skin absorbed doses) were compared with the AOEL for each compound. The actual and absorbed doses of the three pesticides were always lower than the acceptable operator exposure level (AOEL), which are reported to be 234 µg/kg bw, 20 µg/kg bw, and 150 µg/kg bw for pendimethalin, metribuzin, and metolachlor, respectively. In any case, personal protective equipment and spraying devices should be chosen with care to minimize exposure.