Case Study: Solvent Exposure Urine Testing

Case Studies · Case Studies overview

Anonymised case study of a toluene and xylene biomonitoring programme at a UK rotogravure print operation handling solvent-based inks across three presses on a 24-hour shift pattern.

Workplace scenario

Rotogravure print operation, three presses, 24-hour shift pattern, 36 press operators and 8 ink-room technicians. Inks toluene/xylene blend with small ethyl acetate content. Existing LEV at press deck and ink room.

Exposure concern

EH40 review showed toluene and xylene both with skin notation; existing air monitoring covered inhalation only. Workforce raised concern about end-of-shift headaches; ink-room technicians had higher airborne exposure than press operators but spent less time at the highest concentrations.

Monitoring approach

Urinary o-cresol (toluene) and total methylhippuric acids (xylenes) end-of-shift, all press and ink-room SEGs, two shifts per campaign across four campaigns over 12 months. Smoking status recorded; non-smoker subgroup analysed separately. ACGIH BEIs (0.3 mg o-cresol/g creatinine; 1.5 g MHA/g creatinine) used as reference values.

Interpretation themes

Ink-room cohort GM at ~80% of BEI for both biomarkers despite air exposures at 30% of WEL — dermal uptake during manual ink-can decanting identified as the dominant route. Press operators uniformly below 40% of BEI. Night-shift consistently higher than day-shift, traced to lower LEV maintenance attendance overnight.

Control improvements and lessons learned

Pumped ink-transfer replacing manual decanting; nitrile-over-laminate glove protocol for ink-room; night-shift LEV inspection added to engineering rota. Follow-up campaign showed ink-room GM dropping below 30% of BEI for both biomarkers.