Guidance Note: Isocyanates in the Workplace

Written By Lisa Gorski

Introduction

Isocyanates are a group of highly reactive chemicals commonly used in manufacturing processes. Due to their hazardous nature, it is essential to understand their properties, applications, risks, and the legal requirements for managing exposure in the workplace.

What Are Isocyanates?

Isocyanates are chemical compounds containing one or more isocyanate groups (–N=C=O). Common types include:

  • Toluene diisocyanate (TDI)

  • Methylene diphenyl diisocyanate (MDI)

  • Hexamethylene diisocyanate (HDI)

These substances are widely used in the production of:

  • Polyurethane foams

  • Adhesives and sealants

  • Surface coatings (including paints and varnishes)

  • Insulation materials

  • Automotive parts and textiles

Health Hazards of Isocyanates

Short-Term Exposure Risks:

  • Eye and skin irritation

  • Nose and throat irritation

  • Shortness of breath or coughing

  • Headaches or nausea

Long-Term and Chronic Risks:

  • Occupational asthma: Isocyanates are one of the leading causes of occupational asthma in the UK.

  • Sensitisation: Once sensitised, even very low exposure can trigger severe reactions.

  • Potential lung damage and chronic respiratory issues

UK Legislation and Regulatory Framework

The use of isocyanates in the workplace is controlled under several UK regulations:

a. Control of Substances Hazardous to Health (COSHH) Regulations 2002

  • Employers must assess and manage the risk of exposure to hazardous substances.

  • Requires implementation of control measures and health surveillance.

b. REACH (Registration, Evaluation, Authorisation and Restriction of Chemicals)

  • Places restrictions on the marketing and use of certain isocyanates.

  • As of 2023, specific training is required for all professional and industrial users of diisocyanates (≥ 0.1% concentration).

c. Health and Safety at Work etc. Act 1974

  • General duty to ensure, so far as reasonably practicable, the health and safety of employees and others affected by work activities.

d. Personal Protective Equipment at Work Regulations 2022

  • Requires appropriate selection, use, and maintenance of PPE where exposure cannot be adequately controlled by other means.

Required Control Measures

a. Risk Assessment

  • Identify where isocyanates are used.

  • Assess potential for inhalation, skin contact, or accidental release.

b. Substitution and Process Controls

  • Substitute with less hazardous materials if possible.

  • Use closed systems and automated equipment to minimise exposure.

c. Engineering Controls

  • Local exhaust ventilation (LEV) systems.

  • Enclosed spraying booths and properly ventilated mixing areas.

d. Administrative Controls

  • Restrict access to areas where isocyanates are used.

  • Provide appropriate safety signage.

  • Rotate staff to limit individual exposure duration.

e. Personal Protective Equipment (PPE)

  • Respiratory Protective Equipment (RPE): e.g., air-fed masks or powered respirators.

  • Chemical-resistant gloves and coveralls.

  • Eye and face protection.

f. Training and Competence

  • Ensure all users complete required training under REACH by the compliance deadline.

  • Maintain training records and refresh periodically.

Health Surveillance and Monitoring

  • Required for workers who are regularly exposed to isocyanates.

  • Should include baseline and regular lung function tests (e.g., spirometry).

  • Early detection of occupational asthma or sensitisation is critical.

Emergency Procedures

  • Ensure spill kits are available and staff are trained in their use.

  • Establish procedures for exposure incidents, including first aid and medical response.

  • Maintain Material Safety Data Sheets (MSDS) on site for all products containing isocyanates.

Record Keeping

  • Document risk assessments, control measures, health surveillance records, and training logs.

  • Keep records secure and accessible for audit or inspection by the Health and Safety Executive (HSE).

Conclusion

Isocyanates pose significant health risks, particularly respiratory sensitisation and asthma. Compliance with UK regulations and proactive management of workplace exposure are critical to protecting worker health. Regular training, health surveillance, and engineering controls are all essential elements of a robust safety management system.

Further Guidance and Resources

  • HSE Website: www.hse.gov.uk

  • EH40/2005: Workplace exposure limits

  • COSHH Essentials: Guidance for specific tasks

  • UK REACH Helpdesk

Lisa Gorski
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