Table 4. Selected literature on occupational skin exposure to isocyanates

First author [ref.]	Main conclusion	Origin	Study type	Exposure/occupation	Subjects
Pronk [19]	Inhalation HDI exposure associated with tasks involving aerosolisation Skin exposure assessed by extraction of HDI from nitrile gloves; associated with paint-handling tasks and glove use HDA detected in 36% of repair shop workers, 10% of industrial workers HDI oligomers main exposure	Literature search	Cross-sectional study Before and after shift sampling	HDI oligomers, auto-body repair workers	68 paired inhalation and skin samples from auto repair shops; 239 urine samples from 45 workers 27 paired inhalation and skin samples from five industrial companies; 52 urine samples from 10 painters
Robert [55]	MDA detectable in 73% of post-shift urine samples; significantly higher than pre-shift levels Highest MDA levels associated with spraying or hot processes Skin exposure associated with significant MDA levels in urine	Literature search	Cross-sectional study	MDI polyurethane workers	169 workers from 19 French factories and 120 controls
Bello [56]	Quantitative skin wipe sampling method developed 92% of samples under PPE had detectable isocyanate levels, mostly pHDI Highest total isocyanate concentrations associated with spraying and mixing	Literature search	Cross-sectional study	HDI auto-body repair workers	185 samples from 81 auto-body shop painters and technicians during different tasks 43 samples under PPE
Todd [57]	8–21% of workers exposed to mixtures of chemicals more than OELs; 39–69% of surface samples positive for isocyanates using qualitative CLI Swypes™^# PPE and IH controls not adequate	Literature search	Cross-sectional study	Workers at footwear and equipment factories	286 personal air samples, 64 surface, tool or hand samples from four factories in Thailand
Fent [58]	Log-transformed concentrations of HDI in skin of workers correlated with log-transformed product of air concentration and painting time (r=0.79, p<0.001)	Literature search	Cross-sectional study	HDI auto-body spray painters	13 auto-body spray painters: air and skin samples
Liu [59]	Skin exposure algorithm using diaries, task-based skin sampling and PPE Median daily skin exposure index estimated for each worker Associated with job category Weakly correlated with daily airborne exposure	Literature search	Cross-sectional study	Workers in auto-body shops	232 workers in 33 shops: 893 exposure person-days skin exposure, work diary
Fent [60]	Isocyanurate predominant isocyanate Dermal HDI concentrations higher in those not wearing gloves/overalls Isocyante detected on skin during 23% of paint tasks Linear mixed modelling identified breathing-zone concentration and paint time significant predictors skin concentration	Literature search	Cross-sectional study	HDI auto-body spray painters	47 spray painters dermal and inhalational exposure assessment 15 painters no gloves
Flack [61]	HDA detected in 76% plasma samples Correlation between plasma HDA and same day dermal exposures, low but significant, correlation between HDA and 20–60 day dermal exposure higher (r=0.36)	Literature search	Cohort study	HDI auto-body shop painters	46 spray painters: blood, inhalation and dermal exposures measured 288 tasks
Liljelind [62]	Average personal air concentrations below Swedish exposure limit Tape stripping used to measure MDI skin exposure Decreasing levels of MDI in consecutive tape strips per site indicate dermal penetration	Literature search	Cross-sectional study	MDI iron-foundry workers	19 workers in different areas of foundry; tape strip dermal sampling repeated on five exposed skin areas and air sampling

HDI: hexamethylene diisocyanate; HDA: hexamethylene diamine; MDA: methylenedianiline diisocyanate; MDI: methylene diphenyl diisocyante; PPE: personal protective equipment; pHDI: polymeric HDI isocyanate; OEL: occupational exposure limit; IH: industrial hygiene. ^#: skin wipes that provide a visible indication of skin exposure (Colorimetric Laboratories, Inc., Plaines, IL, USA).