Workplace Chemical Exposure

Industrial Processes · Industrial Processes overview

Workplace chemical exposure is the inhalation, dermal contact or inadvertent ingestion of hazardous substances arising from work activities. In UK industry, organic solvent vapours, isocyanates, formaldehyde and other airborne chemicals present the most common and significant occupational chemical risks.

Understanding workplace chemical exposure

Occupational chemical exposure occurs when hazardous substances are released into the work environment through handling, processing, storage, transfer or disposal. The primary route for volatile substances is inhalation. Dermal absorption is significant for some solvents and reactive chemicals. Ingestion is less common but can occur through hand-to-mouth contact or contamination of food and drink.

Exposure potential depends on the physical form of the substance, its volatility, the temperature, the nature of the task, the duration and frequency of contact, and the effectiveness of engineering and administrative controls. Workplace chemical exposure assessment must therefore consider the full range of exposure routes, not only airborne concentrations.

Sources of chemical exposure in UK workplaces

Solvent-based processes are the dominant source of occupational chemical exposure in manufacturing, maintenance and repair. Paint spraying releases solvent vapours and aerosolised paint. Parts cleaning and degreasing uses hydrocarbon, chlorinated or oxygenated solvents that evaporate at room temperature. Printing, coating and adhesive application all generate airborne chemical mixtures that may include toluene, xylene, acetone, methyl ethyl ketone, naphtha and other VOCs.

Composite manufacturing with open-mould GRP releases styrene vapour at high concentrations. Epoxy and polyurethane resin work generates vapours and aerosols containing sensitising chemicals. Laboratory operations, histology processes and quality-control testing involve routine handling of organic solvents, fixatives and reagents. Manufacturing emissions from heated plastics, rubber and bitumen add further chemical contaminants to the workplace atmosphere.

Paint spraying, coating and surface finishing operations
Parts cleaning, degreasing and equipment maintenance
Printing, lamination and packaging processes
Composite layup, resin application and curing
Laboratory, histology and analytical chemistry work
Heated plastic, rubber and bitumen processing

Health effects of occupational chemical exposure

Acute effects of solvent vapour exposure include headache, dizziness, nausea, throat and eye irritation, and impaired coordination. These symptoms typically appear at concentrations above a few hundred parts per million for common solvents and are often the first indicator that controls are inadequate.

Repeated or chronic exposure can cause more serious conditions. Organic solvent exposure is associated with neurotoxicity, peripheral neuropathy and cognitive impairment. Benzene is a known human carcinogen causing leukaemia. Formaldehyde is classified as carcinogenic to humans. Isocyanates are potent respiratory sensitisers capable of causing occupational asthma. Styrene exposure affects the nervous system and may cause hearing loss at chronic levels.

Dermal effects include dermatitis, chemical burns and sensitisation. Some solvents penetrate intact skin and contribute to systemic toxicity in addition to inhalation exposure. The combined effect of multiple routes must be considered in any exposure assessment.

Assessment and control under COSHH

COSHH requires employers to assess the risk to health created by work involving hazardous substances and to prevent or, where prevention is not reasonably practicable, control exposure. The hierarchy of control begins with elimination or substitution of the hazardous substance. Where this is not feasible, engineering controls such as enclosure, local exhaust ventilation and process isolation should be applied.

Administrative controls, including restricted access, job rotation and procedural limits, supplement engineering measures. Respiratory protective equipment is the last line of defence and is only acceptable where exposure cannot be reduced sufficiently by other means. Personal protective equipment for the skin and eyes is required where dermal contact is likely.

Exposure assessment combines qualitative evaluation of tasks and controls with quantitative air monitoring where WELs exist or where there is uncertainty about exposure levels. Health surveillance may be required for substances known to cause occupational disease, such as isocyanates and certain solvents.

Practical steps to reduce workplace chemical exposure

The most effective intervention is to replace the hazardous substance with a safer alternative. Water-based paints, low-VOC adhesives, aqueous degreasing systems and UV-cured coatings all reduce solvent vapour exposure. Where substitution is not possible, process enclosure and automated application reduce operator contact.

Local exhaust ventilation with correctly positioned capture hoods is essential for spray painting, welding, parts cleaning and resin work. General dilution ventilation supports LEV but should not be relied upon as the primary control for substances with low WELs. Good housekeeping, sealed storage and spill control prevent fugitive emissions.

Training ensures that workers understand the hazards, know how to use controls correctly, and report defects immediately. Supervisory checks and periodic audit maintain control performance over time.

Frequently asked questions

What is the difference between occupational and environmental chemical exposure?

Occupational exposure occurs in the workplace and is typically higher, more frequent and more specific than environmental exposure. Occupational hygiene focuses on the tasks, processes and controls that create and manage exposure during work. Environmental exposure refers to background levels in the general environment.

Which industries have the highest workplace chemical exposure?

Spray painting, composite manufacturing, printing, parts cleaning, pharmaceutical production, laboratories, rubber and plastics processing, and road surfacing all report significant solvent and vapour exposure. The risk depends on the substance, process and control regime rather than the industry alone.

What are the early warning signs of excessive solvent exposure?

Headache, dizziness, nausea, throat irritation, eye watering and a characteristic solvent smell on clothing or breath are common early indicators. These should prompt immediate review of ventilation, task duration and RPE use.

Is health surveillance mandatory for solvent exposure?

Health surveillance is required under COSHH for specific substances and exposures listed in Schedule 6 of the regulations. For many solvents, surveillance is not mandatory unless there is a reasonable likelihood of occupational disease and valid techniques are available to detect it.

How does COSHH apply to small businesses?

COSHH applies to all employers, regardless of size. Small businesses must carry out suitable and sufficient risk assessments, implement controls, provide information and training, and monitor exposure where WELs exist. The duty is proportionate to the risk.

Can multiple chemical exposures interact?

Yes. Simultaneous exposure to several solvents can produce additive or synergistic effects. Some solvent mixtures are more toxic than the individual components. Risk assessments should consider combined exposure where multiple substances are present.