Contact dermatitis in the construction industry: the role of filaggrin loss-of-function mutations

Identifying and Prioritizing Hazardous Chemicals in Construction Metal Structure Coating Systems: A Roadmap for Data-Driven Disease Prevention

INTRODUCTION

Occupational exposure as a painter was classified by the International Agency for Research on Cancer (IARC) as a Group 1 carcinogen (carcinogenic to humans) in 1989. Chemical agents responsible for cancers and other illnesses among industrial painters are not well-documented. The goal of this systematic review and synthesis was to document the chemistries of metal structure coating systems, summarize data gaps on occupational exposures and health effects among painters, and identify and prioritize hazardous chemicals to guide future exposure and occupational health studies, and ultimately disease prevention efforts.

METHODS

We reviewed coating products approved by the Northeast Protective Coating Committee (NEPCOAT) for use in steel bridges in New England, with a special focus on Part B of these reactive chemical systems, and related literature on exposures and health effects.

RESULTS

From the review of safety datasheets (SDS), we identified 61 unique CAS numbers belonging to different Part B chemical groups of isocyanate- and epoxy-based formulations, including amine hardeners, solvents, nanomaterials, and other additives. The list of identified ingredients contained 14 potent sensitizers, two IARC Group 1 known carcinogens, and 7 IARC Group 2B possible carcinogens. Cancers of the lungs, urinary bladder, liver, kidneys, and gastrointestinal system, allergic contact dermatitis, lung fibrosis, and asthma were some possible disease endpoints. Existing occupational exposure studies focused on solvent exposures, while exposure and biomonitoring studies of amine hardeners and other ingredients of concern in these formulations are lacking.

CONCLUSIONS

The list of chemicals of concern identified here, including sensitizers and carcinogens, can serve as a basis for analytical method development and field exposure assessment studies. A national multi-pronged strategy to reduce chemical exposures and health risks among construction painters is warranted, including research on exposure monitoring and reduction efforts, longitudinal epidemiological studies, and product reformulation.

Occupational Contact Dermatitis in Construction Workers: A Retrospective Analysis of the North American Contact Dermatitis Group Data, 2001-2020

Background: Construction workers (CWs) are at risk for occupational contact dermatitis (CD) owing to workplace exposures. Objective: Determine the prevalence of occupational allergic CD and characterize common occupational allergens in CWs referred for patch testing in the United States and Canada. Methods: Retrospective cross-sectional analysis of patients patch tested by the North American Contact Dermatitis Group from 2001 to 2020. Results: Of 47,843 patch-tested patients, 681 (1.4%) were CWs. Compared with non-CWs, CWs were more likely to be male (91.0% vs 30.9%) have occupational skin disease (36.9% vs 11.4%) and have hand involvement (37.2% vs 22.5%) (all P < 0.0001). Of 681 CWs, 60.1% (411) had clinically relevant positive patch test reactions, and nearly 1/3 of CWs (128) had occupationally relevant reactions. Most common occupationally relevant allergens were potassium dichromate 0.25% pet. (30.5%, 39/128), bisphenol A epoxy resin 1% pet. (28.1%, 36/128), carba mix 3% pet. (14.8%, 19/128), cobalt (ii) chloride hexahydrate 1% pet. (14.1%, 18/128), and thiuram mix 1% pet. (14.1%, 18/128). Top sources of occupationally relevant allergens were cement/concrete/mortar (20.4%, 46/225), gloves (15.1%, 34/225), and coatings (paint/lacquer/shellac/varnish/stains) (9.8%, 22/225). Conclusions: Occupational CD in North American CWs is common. In this group, frequently identified etiological sources of occupational allergic CD included metals, epoxy resin, and rubber.

Increased loss-of-function filaggrin gene mutation prevalence in atopic dermatitis patients across northern latitudes indicates genetic fitness: A systematic review and meta-analysis

Loss-of-function (LoF) mutations in the filaggrin gene (FLG) constitute the strongest genetic risk for atopic dermatitis (AD). A latitude-dependent difference in the prevalence of LoF FLG mutations was systematically evaluated. A systematic review and meta-analysis were performed to estimate the prevalence of LoF FLG mutations in AD patients and the general population by geography and ethnicity. Risk of bias was assessed by Newcastle-Ottawa Scale and Jadad score. StatsDirect, version 3 software was used to calculate all outcomes. PubMed and EMBASE were searched until 9th December 2021. Studies were included if they contained data on the prevalence of LoF FLG mutations in AD patients or from the general population or associations between AD and LoF FLG mutations and were authored in English. Overall, 248 studies and 229 310 AD patients and individuals of the general population were included in the quantitative analysis. The prevalence of LoF FLG mutations was 19.1% (95% CI, 17.3-21.0) in AD patients and 5.8% (95% CI, 5.3-6.2) in the general population. There was a significant positive association between AD and LoF FLG mutations in all latitudes in the Northern hemisphere, but not in all ethnicities. The prevalence of LoF FLG mutations became gradually more prevalent in populations residing farther north of the Equator but was negligible in Middle Easterners and absent in most African populations. FLG LoF mutations are common and tend to increase with northern latitude, suggesting potential clinical implications for future AD management. The existence of possible genetic fitness from FLG LoF mutations remains unknown.

Skin Barrier Function and Its Relationship With IL-17, IL-33, and Filaggrin in Malar Melasma

BACKGROUND

The pathogenesis of melasma remains unclear. Interleukin (IL)-17, a proinflammatory mediator, disturbs barrier function. Filaggrin (FLG) is a protein involved in epidermal barrier homeostasis and may be affected by IL-17 and IL-33.

OBJECTIVE

To evaluate epidermal barrier function in malar melasma and its association with the expression of FLG, IL-17, and IL-33.

METHODS

Twenty patients with malar melasma were included in this study. Colorimetric and transepidermal water loss (TEWL) was measured in lesional and adjacent unaffected skin at baseline and 30 minutes after barrier disruption using the tape-stripping test. Biopsies from melasma and perilesional skin were performed to evaluate the presence of FLG by immunohistochemistry, and profilaggrin, IL-17, and IL-33 expression were analyzed by reverse transcription-qualitative polymerase chain reaction.

RESULTS

After the stripping test, the erythema and TEWL values were higher in the melasma than in the unaffected skin ( P = 0.01). Thirty minutes later, TEWL diminished, but it remained higher than in the perilesional skin. Profilaggrin increased as TEWL gradually decreased (R = -0.68, P = 0.04). FLG and IL-17 were higher in the melasma than in the perilesional skin ( P = 0.003). IL-17 and profilaggrin expression were positively associated (R = 0.60, P = 0.04). IL-33 expression was higher in the adjacent normal skin than in the melasma ( P = 0.01).

CONCLUSION

This study found subclinical inflammation in the skin adjacent to the melasma, dysfunction of the epidermal barrier in lesions associated with chronic inflammation, and an abnormal differentiation process promoting an increase in FLG. These findings highlight the need to preserve the integrity of the facial stratum corneum in these patients.

Contact Dermatitis in Construction Workers in Northeastern Italian Patch Test Database Between 1996 and 2016

BACKGROUND

Contact dermatitis in construction workers (CWs) is frequent due to the widespread exposure to sensitizing substances and irritating agents and the wet and cold working conditions.

OBJECTIVE

Our objectives were to evaluate contact dermatitis characteristics among CWs who underwent patch test in northeastern Italy and to identify related allergens.

METHODS

Seven hundred ninety-five CWs were studied and their data were compared to 2.099 male white-collar workers. The associations between patch test results and occupations were assessed by multivariate logistic regression analysis. Incidence data were calculated from 1996 to 2016.

RESULTS

CWs with confirmed occupational dermatitis presented an increased risk to be sensitized to potassium dichromate [OR 3.1 (95%IC 2.0-4.8)], to thiurams [OR 8 .6 (95%IC 4.0-18.4)], and to epoxy resins [OR 12.7 (95%IC 6.1-26.4)]. Sensitization to chromate decreased significantly after 2004, following EU regulation of chromate content in concrete, while sensitization to epoxy resins and thiurams increased. The overall incidence of occupational contact dermatitis in CWs decreased significantly.

CONCLUSION

Our study demonstrated the effectiveness of EU regulations in reducing chromate sensitization in CWs and the overall incidence of occupational contact dermatitis. However, sensitization to other haptens is increasing, though improvement of protective measures is compulsory.

Characterization and Quantitation of Personal Exposures to Epoxy Paints in Construction Using a Combination of Novel Personal Samplers and Analytical Techniques: CIP-10MI, Liquid Chromatography-Tandem Mass Spectrometry and Ion Chromatography

Epoxy resins are extremely versatile products that are widely used in construction for coatings, adhesives, primers, and sealers. Occupational exposures to epoxies cause allergic contact dermatitis, occupational asthma, hypersensitivity pneumonitis (epoxy-resin lung) and acute decline in lung function. Despite these health concerns, there is a striking paucity of quantitative exposure data to epoxy resins in construction. The lack of practical analytical methods and suitable personal samplers for monitoring of reactive two-component epoxide systems in real-world applications has been an unmet challenge for decades. Sampling and analysis methods for epoxies should be able to collect the paint aerosols efficiently, stop polymerization reactions at the time of sample collection, and subsequently provide detailed multispecies characterization of epoxides, as well as the total epoxide group (TEG) content of a sample, to properly document the chemical composition of exposures to epoxide paints. In this work, we present the development and application of two new complementary quantitative analytical methods-liquid chromatography-tandem mass spectrometry with online ultraviolet detection and ion chromatography (IC)-for multispecies characterization of raw products, as well as inhalation and skin exposures to epoxy formulations in real-world construction applications. A novel personal sampler, CIP-10MI, was used for personal sampling of airborne epoxies. We report for the first time the results of personal inhalation and potential skin exposures to individual monomers and oligomers of bisphenol A diglycidyl ether (BADGE), as well as TEG, during metal structure coatings in construction; compare analytical results of the two analytical methods; and provide recommendations for method selection in future field studies. High inhalation and potential skin exposures to epoxies point to the need for interventions to reduce exposures among painters in construction.

Effectiveness of secondary prevention in metalworkers with work-related skin diseases and comparison with participants of a tertiary prevention program: A prospective cohort study

BACKGROUND

In Germany, a multistep approach has been established to prevent work-related skin diseases (WRSDs).

OBJECTIVES

To evaluate the effect of a secondary individual prevention program (SIP) in metalworkers with WRSD and to compare their characteristics with those of participants of a tertiary individual prevention program (TIP).

PATIENTS AND METHODS

In a prospective cohort study, metalworkers with WRSD of the hands participating either in the SIP (n = 114) or in the TIP (n = 83) were recruited. At baseline and at the respective follow-up 8-12 weeks after the SIP or at dismissal from the TIP (3-4 weeks later), questionnaires were completed and the severity of WRSD was assessed. Saliva samples were collected for assessment of filaggrin (FLG) mutations and an explorative genome-wide association study (GWAS).

RESULTS

Ninety-three SIP patients (81.6%) attended the follow-up. Disease severity was significantly reduced, and knowledge and protective behavior were significantly improved compared to baseline. Significant differences between SIP and TIP patients were found regarding duration and severity of symptoms, work absenteeism, tobacco smoking, and presence of atopic dermatitis, but not regarding FLG mutations and by GWAS.

CONCLUSIONS

The SIP was effective in metalworkers with WRSDs. Individual factors may influence the course of the disease and the need for the TIP.

Molecular Mechanism of Epidermal Barrier Dysfunction as Primary Abnormalities

Epidermal barrier integrity could be influenced by various factors involved in epidermal cell differentiation and proliferation, cell–cell adhesion, and skin lipids. Dysfunction of this barrier can cause skin disorders, including eczema. Inversely, eczema can also damage the epidermal barrier. These interactions through vicious cycles make the mechanism complicated in connection with other mechanisms, particularly immunologic responses. In this article, the molecular mechanisms concerning epidermal barrier abnormalities are reviewed in terms of the following categories: epidermal calcium gradients, filaggrin, cornified envelopes, desquamation, and skin lipids. Mechanisms linked to ichthyoses, atopic dermatitis without exacerbation or lesion, and early time of experimental irritation were included. On the other hand, the mechanism associated with epidermal barrier abnormalities resulting from preceding skin disorders was excluded. The molecular mechanism involved in epidermal barrier dysfunction has been mostly episodic. Some mechanisms have been identified in cultured cells or animal models. Nonetheless, research into the relationship between the causative molecules has been gradually increasing. Further evidence-based systematic data of target molecules and their interactions would probably be helpful for a better understanding of the molecular mechanism underlying the dysfunction of the epidermal barrier.

Functional and proteomic analysis of a full thickness filaggrin-deficient skin organoid model

Background: Atopic eczema is an itchy inflammatory disorder characterised by skin barrier dysfunction. Loss-of-function mutations in the gene encoding filaggrin ( FLG) are a major risk factor, but the mechanisms by which filaggrin haploinsufficiency leads to atopic inflammation remain incompletely understood. Skin as an organ that can be modelled using primary cells in vitro provides the opportunity for selected genetic effects to be investigated in detail.

Methods: Primary human keratinocytes and donor-matched primary fibroblasts from healthy individuals were used to create skin organoid models with and without siRNA-mediated knockdown of FLG. Biological replicate sets of organoids were assessed using histological, functional and biochemical measurements.

Results:FLG knockdown leads to subtle changes in histology and ultrastructure including a reduction in thickness of the stratum corneum and smaller, less numerous keratohyalin granules. Immature organoids showed some limited evidence of barrier impairment with FLG knockdown, but the mature organoids showed no difference in transepidermal water loss, water content or dye penetration. There was no difference in epidermal ceramide content. Mass spectrometry proteomic analysis detected >8000 proteins per sample. Gene ontology and pathway analyses identified an increase in transcriptional and translational activity but a reduction in proteins contributing to terminal differentiation, including caspase 14, dermokine, AKT1 and TGF-beta-1. Aspects of innate and adaptive immunity were represented in both the up-regulated and down-regulated protein groups, as was the term ‘axon guidance’.     

Conclusions: This work provides further evidence for keratinocyte-specific mechanisms contributing to immune and neurological, as well as structural, aspects of skin barrier dysfunction. Individuals with filaggrin deficiency may derive benefit from future therapies targeting keratinocyte-immune crosstalk and neurogenic pruritus.

Filaggrin variations are associated with PAH metabolites in urine and DNA alterations in blood

Dermal chemical exposure is common in many professions. The filaggrin protein is important for the skin barrier and variations in the filaggrin gene (FLG) may influence the uptake of chemicals via the skin, and consequently, the degree of systemic effects. The aim of this study was to investigate, in chimney sweeps with occupational exposure to polycyclic aromatic hydrocarbons (PAH) from soot, the influence of variation in FLG on internal PAH dose and DNA alterations, including epigenetic, previously linked to cancer and cardiovascular disease. We used TaqMan PCR to genotype 151 chimney sweeps and 152 controls for four FLG null variants (R501X, R2447X, S3247X and 2282del4) which cause impaired skin barrier, and FLG copy number variation (12th repeat, CNV12) which potentially is beneficial for the skin barrier. The internal dose of PAH was represented by urinary PAH metabolites (e.g. 1-hydroxypyrene and 3-hydroxybenzo[a]pyrene) that we measured by LC-MS/MS. We measured epigenetic alterations (methylation of AHRR and F2RL3) in blood by pyrosequencing; and DNA alterations (telomere length and mitochondrial DNA copy number) by real-time PCR. Hypomethylation of AHRR or F2RL3 is a risk factor for lung cancer and shorter telomere length a risk factor for cardiovascular disease. The frequencies of FLG null were 8.6 and 11.8% (p = 0.35), and CNV12 27.8 and 19.7% (p = 0.09) in chimney sweeps and controls, respectively. We found that among chimney sweeps working predominately with soot sweeping (high PAH exposure), CNV12 carriers had lower concentrations of PAH metabolites in urine compared with non-carriers (median 1-hydroxypyrene = 0.37 vs 0.86 μg/g creatinine respectively; p = 0.025 by linear regression models adjusted for age, BMI and smoking) compared to sweeps not carrying CNV12. Further, FLG null was associated with approximately 2.5% higher methylation of F2RL3 (cg03636183, p = 0.019 after adjustment for exposure group, age, BMI and smoking). FLG null was associated with approximately 7% shorter telomere length (p = 0.015, adjusted model). Our results suggest that FLG variations may influence the dose of PAH in highly exposed workers, possibly via dermal uptake. It also suggests that FLG variation may influence the degree of (epi)genotoxicity in the body. FLG variation is common in the working population and should be considered in risk assessment.

Proteomic analysis of a filaggrin-deficient skin organoid model shows evidence of increased transcriptional-translational activity, keratinocyte-immune crosstalk and disordered axon guidance

Background:Atopic eczema is an itchy inflammatory disorder characterised by skin barrier dysfunction. Loss-of-function mutations in the gene encoding filaggrin (FLG) are a major risk factor, but the mechanisms by which filaggrin haploinsufficiency leads to atopic inflammation remain incompletely understood. Skin as an organ that can be modelled using primary cellsin vitroprovides the opportunity for selected genetic effects to be investigated in detail.Methods:Primary human keratinocytes and donor-matched primary fibroblasts from healthy individuals were used to create skin organoid models with and without siRNA-mediated knockdown ofFLG. Biological replicate sets of organoids were assessed using histological, functional and biochemical measurements.Results:FLGknockdown leads to subtle changes in histology and ultrastructure including a reduction in thickness of the stratum corneum and smaller, less numerous keratohyalin granules. Immature organoids showed evidence of barrier impairment withFLGknockdown, but the mature organoids showed no difference in transepidermal water loss, water content or dye penetration. There was no difference in epidermal ceramide content. Mass spectrometry proteomic analysis detected >8000 proteins per sample. Gene ontology and pathway analyses identified an increase in transcriptional and translational activity but a reduction in proteins contributing to terminal differentiation, including caspase 14, dermokine, AKT1 and TGF-beta-1. Aspects of innate and adaptive immunity were represented in both the up-regulated and down-regulated protein groups, as was the term ‘axon guidance’.     Conclusions:This work provides further evidence for keratinocyte-specific mechanisms contributing to immune and neurological, as well as structural, aspects of skin barrier dysfunction. Individuals with filaggrin deficiency may derive benefit from future therapies targeting keratinocyte-immune crosstalk and neurogenic pruritus.

Dermatitis among workers in Ontario: results from the Occupational Disease Surveillance System

Objectives

Dermatitis is the most common occupational skin disease, and further evidence is needed regarding preventable risk factors. The Occupational Disease Surveillance System (ODSS) derived from administrative data was used to investigate dermatitis risk among industry and occupation groups in Ontario.

Methods

ODSS cohort members were identified from Workplace Safety and Insurance Board (WSIB) accepted lost time claims. A case was defined as having ≥2 dermatitis physician billing claims during a 12-month period within 3 years of cohort entry. A 3-year look-back period prior to cohort entry was used to exclude prevalent cases without a WSIB claim. Workers were followed for 3 years or until dermatitis diagnosis, age 65 years, emigration, death or end of follow-up (31 December 2016), whichever occurred first. Age-adjusted and sex-adjusted Cox proportional hazard models estimated HRs and 95% CIs. The risk of dermatitis was explored using a job exposure matrix that identifies exposure to asthmagens, many of which also cause contact dermatitis.

Results

Among 597 401 workers, 23 843 cases of new-onset dermatitis were identified. Expected elevated risks were observed among several groups including furniture and fixture industries, food and beverage preparation and chemicals, petroleum, rubber, plastic and related materials processing occupations and workers exposed to metal working fluids and organic solvents. Decreased risk was observed among farmers, nurses and construction industries, and occupations exposed to latex and indoor cleaning products.

Conclusions

ODSS can contribute to occupational dermatitis surveillance in Ontario by identifying occupational groups at risk of dermatitis that can then be prioritised for prevention activities.

Transient epidermal barrier deficiency and lowered allergic threshold in filaggrin-hornerin (FlgHrnr-/- ) double-deficient mice

BACKGROUND

Filaggrin (Flg) and hornerin (Hrnr) share similar structural and functional features. Both proteins have been implicated as essential proteins for skin barrier maintenance. Loss-of-function mutations of these genes constitute a risk factor for atopic dermatitis and eczema-related asthma. Furthermore, both FLG and HRNR protein levels are downregulated in patients with atopic dermatitis. Thus, mice deficient for Flg and Hrnr provide a novel model to study skin barrier impairment and the susceptibility for cutaneous inflammation.

METHODS

By using appropriate targeting vectors and breeding strategies, we established a homozygous FlgHrnr double-deficient (FlgHrnr^-/- ) mouse model lacking both genes including the intergenomic sequence.

RESULTS

Neonates appeared normal, but developed a transient scaly phenotype with overall flaky appearance, but no overt skin phenotype in adulthood, thereby reflecting a subclinical barrier defect seen in humans. Structurally, FlgHrnr^-/- mice displayed a markedly reduced granular layer and a condensed cornified layer. Functionally, FlgHrnr^-/- mice showed permeability abnormalities and metabolic aberrations regarding the production of natural moisturizing factors (NMFs) in the stratum corneum. Surprisingly, although the immune system revealed no aberrations under steady-state conditions, FlgHrnr^-/- mice are predisposed to mount an allergic contact dermatitis, especially at hapten threshold levels eliciting allergic reactions.

CONCLUSIONS

Together, our FlgHrnr^-/- mouse model nicely reflects the epicutaneous sensitization susceptibilities and inflammatory reactions to environmental insults in humans with impaired skin barrier functions.

Genetic variants of filaggrin are associated with occupational dermal exposure and blood DNA alterations in hairdressers

Hairdressers are exposed to high levels of chemicals, including possible carcinogens. For dermal exposure, the skin protects against the uptake of chemicals and the protein filaggrin (encoded by FLG) has a key role in skin barrier function. This study investigated if variants of FLG previously linked to impaired skin barrier function, i.e. null mutations and copy number variation (CNV) alleles (CNV10), are associated with cancer-related DNA changes. Blood and questionnaire data were collected from hairdressers (n = 295) and controls (n = 92). Exposure to aromatic amines was measured as hemoglobin adducts by gas chromatography tandem mass spectrometry. DNA from peripheral blood was used to test for FLG null mutations and CNV (10, 11, or 12 repeats), telomere length, and methylation of selected cancer-related genes. Hairdressers had a lower frequency of FLG null mutations (4.1 vs. 7.6%, P = 0.18) and CNV10 (43.2 vs. 56%, P = 0.0032) than controls. In hairdressers, CNV10 carriers had a decreased risk of high ortho-toluidine adducts in blood compared with non-carriers (odds ratio, OR = 0.49, 95% CI = 0.30-0.81). Further, telomere length was shorter for carriers of any FLG null allele (β = -0.18, 95% CI = -0.31 to -0.044) and CNV10 carriers (β = -0.054, 95% CI = -0.11 to -0.00051, linear regression adjusted for age, passive smoking, residence, and education) compared to non-carriers. Carriers of any FLG null allele showed higher methylation of the cyclin-dependent kinase inhibitor 2A gene CDKN2A (OR = 6.26, CI = 1.13-34.7), but not of the other genes analyzed. These associations were not found among the controls. Our study showed that the frequency of FLG CNV10 was lower among hairdressers than controls, which may indicate a healthy worker selection. Moreover, FLG null and CNV10 were associated with cancer-related DNA changes in hairdressers, which may influence their risk of cancer.

Contact dermatitis is an unrecognized problem in the construction industry: Comparison of four different assessment methods

BACKGROUND

A high contact dermatitis symptoms prevalence has been observed in Dutch construction workers.

METHODS

Contact dermatitis was diagnosed by an expert panel using questionnaire data and photographs of 751 subjects' hands. A subset was evaluated by two occupational physicians. Their diagnoses were compared to those of the expert panel. In addition, two self-reported questionnaire-based assessment methods were compared to the expert panel evaluation. Associations between contact dermatitis and determinants were assessed using log-binomial regression analysis.

RESULTS

Contact dermatitis prevalence was high: 61.4% (expert panel's diagnosis) and 32.9% (self-reported). Agreement between occupational physicians and the expert panel was low but increased after training. Washing hands with solvents and performing job-related tasks at home were related to contact dermatitis.

CONCLUSIONS

Contact dermatitis prevalence among construction workers is high. Recognition of contact dermatitis by occupational physicians is poor but can be improved by training. Awareness of skin disorders should be raised.