Occupational Health Risk Assessment of Chemical Exposure in a Pharmaceutical Manufacturing Facility in Oyo State

Pharmaceutical manufacturing workers in Nigeria face occupational exposure to potent active pharmaceutical ingredients and chemical excipients, yet formal occupational health risk assessments are infrequently documented for facilities in South West Nigeria. This study conducts an occupational health risk assessment for chemical agent exposure at a medium-scale pharmaceutical manufacturing facility in Ibadan, Oyo State, producing solid dosage forms including tablets and capsules. The risk assessment followed the UK Health and Safety Executive COSHH Essentials approach, supplemented by quantitative air monitoring at selected high-exposure tasks. Chemical agents assessed included paracetamol, metronidazole, ascorbic acid, aerosil, magnesium stearate, isopropyl alcohol, and dichloromethane. Airborne concentration measurements were conducted using personal sampling pumps and analysed by HPLC and GC methods. Dichloromethane exceeded the UK workplace exposure limit of 100 ppm at granulation and film-coating workstations, with measured concentrations reaching 148 ppm. Isopropyl alcohol was approaching but did not exceed its occupational exposure limit. A substitution assessment confirmed that dichloromethane could be replaced with ethanol-water mixtures for the film-coating application with minor formulation adjustment. The study recommends immediate implementation of local exhaust ventilation at film-coating operations, health surveillance for chronic solvent exposure markers, and a 12-month timeline for dichloromethane substitution. Keywords: occupational health, pharmaceutical manufacturing, dichloromethane, chemical exposure, Oyo State