Hazardous Substances in the Workplace: Risks, Health Effects & Prevention

Hazardous substances in the workplace are chemicals, dusts, fumes, gases, vapours, biological agents, and materials that can harm workers' health or safety if they are inhaled, swallowed, touched, or absorbed through the skin. Common examples include cleaning chemicals, solvents, asbestos, silica dust, pesticides, lead, toxic gases, and corrosive substances. Preventing harm requires proper hazard identification, risk assessment, Safety Data Sheets, safe handling, storage, PPE, ventilation, training, and emergency procedures.

What Are Hazardous Substances in the Workplace?

Quick Answer: Hazardous substances are any materials that can damage health, cause injury, trigger disease, or create fire, explosion, or environmental risks at work.

Hazardous substances cover a broad range of chemical, physical, and biological agents used or produced across industries. They may exist as liquids, solids, gases, dusts, or vapours, and exposure can happen through handling, storage, transport, or accidental release.

Common examples include:

• Solvents
• Cleaning chemicals
• Silica dust
• Asbestos
• Lead
• Pesticides
• Toxic gases
• Chemical fumes
• Flammable substances
• Corrosive chemicals
• Biological agents

Industries where exposure is common include construction, manufacturing, healthcare, agriculture, mining, oil and gas, and waste management.

Hazardous substances vs. hazardous chemicals vs. hazardous materials: these terms are often used interchangeably, but 'hazardous chemicals' typically refers to manufactured products (solvents, acids); 'hazardous materials' (HazMat) often relates to transport and storage classification; and 'hazardous substances' is the broader occupational health and safety term covering chemical, physical, and biological agents combined.

Why Hazardous Substances Are a Serious Workplace Safety Risk

Exposure to hazardous substances creates immediate and long-term dangers. Short-term exposure risks include burns, poisoning, breathing difficulty, dizziness, and skin or eye irritation. Long-term occupational health effects include cancer, chronic respiratory disease, organ damage, and neurological harm — often developing silently over years.

Beyond worker health, hazardous substances create serious legal and compliance risks for businesses, including regulatory penalties and prosecution for breaches of workplace safety compliance. Business risks include operational downtime, compensation claims, insurance costs, and reputational damage following an incident.

Worker risks include burns, poisoning, respiratory illness, cancer, and organ damage — making OSHA's chemical hazards and toxic substances overview  one of the leading causes of occupational exposure to chemicals and long-term ill health globally.

Common Types of Hazardous Substances at Work

Chemical Hazards

• Acids
• Solvents
• Paints
• Disinfectants
• Degreasers
• Pesticides

Dusts, Fumes and Vapours

• Silica dust
• Welding fumes
• Chemical vapours
• Paint fumes
• Diesel exhaust

Biological and Toxic Substances

• Mould
• Bacteria
• Healthcare waste
• Contaminated fluids

Flammable, Corrosive and Reactive Materials

• Fuel
• Compressed gases
• Corrosive cleaners
• Oxidisers

Health Effects of Hazardous Substances

Understanding chemical exposure health effects is essential for prevention. Toxic substances health effects vary depending on the concentration, duration, and route of exposure. Chemical inhalation hazards and respiratory hazards in the workplace are among the most common causes of occupational lung disease, while skin exposure to chemicals is a leading cause of workplace dermatitis. Effective chemical burns prevention relies on proper PPE, safe handling practices, and immediate first-aid response protocols.

Who Is Most at Risk from Workplace Chemical Exposure?

Certain roles face higher exposure risk due to the nature of their work:

• Construction workers
• Manufacturing workers
• Oil and gas workers
• Healthcare and cleaning staff
• Warehouse and logistics workers
• Laboratory workers
• Maintenance technicians
• Waste management teams
• New workers and untrained employees

Workers are at higher risk when they do not understand chemical labels, SDS information, safe handling procedures, PPE requirements, or emergency response steps. In the UK, these obligations fall under the HSE's COSHH (Control of Substances Hazardous to Health) framework, which requires employers to assess exposure, apply controls, and provide information, instruction, and training.

How to Conduct a Hazardous Substances Risk Assessment

A hazardous substances risk assessment is a structured process used to identify chemical hazards, evaluate exposure, and apply the right controls to protect workers.

Step 1 — Identify Hazardous Substances

Start by identifying every hazardous substance present in the workplace:

• Check product labels
• Review Safety Data Sheets
• Inspect storage areas
• Observe tasks being carried out
• Identify by-products such as fumes, dust, and vapours

Step 2 — Understand Who May Be Exposed

Exposure isn't limited to the person directly handling a substance. Consider:

• Workers
• Contractors
• Cleaners
• Visitors
• Maintenance staff
• Emergency responders

Step 3 — Evaluate Exposure Routes

Assess how workers could come into contact with the substance:

• Inhalation
• Skin contact
• Eye contact
• Ingestion
• Injection through cuts or punctures

Step 4 — Apply Control Measures

Once exposure routes are understood, controls must be applied using the hierarchy of controls (covered below) to reduce or eliminate risk.

Step 5 — Review, Train and Update

Risk assessments are not one-time tasks. Review and update them when there are:

• New chemicals introduced
• Process changes
• Incident reports
• Updated SDS
• Worker feedback

Control Measures for Hazardous Substances

The most effective way to manage hazardous substances is by applying the Hierarchy of Controls:

1. Elimination — remove the hazardous substance entirely
2. Substitution — use a safer product instead
3. Engineering Controls — ventilation, enclosed systems, extraction
4. Administrative Controls — procedures, permits, training, exposure limits
5. PPE — gloves, goggles, respirators, protective clothing

PPE should not be the first or only control. It should support stronger controls such as elimination, substitution, ventilation, and safe systems of work. This principle is central to OSHA's guidance on controlling chemical exposure, which states that engineering and work practice controls must be the primary means of reducing exposure, with PPE used only when other controls are infeasible.

Safety Data Sheets, GHS Labels and Hazard Communication

A safety data sheet (SDS), sometimes still referred to as a material safety data sheet (MSDS), provides essential information on a chemical's hazards, safe handling, storage, PPE requirements, and emergency response. Workers must know how to read SDS sections to understand risks before handling any substance.

GHS hazard symbols and GHS labels communicate hazards quickly through standardised pictograms, so chemical labels must always stay visible and legible. Decanting chemicals into unlabelled bottles is dangerous because it removes critical hazard information, increasing the risk of misuse or accidental exposure. This is why hazard communication training is a core part of workplace chemical safety.

Safe Handling and Storage of Hazardous Chemicals

Safe storage and handling practices reduce the risk of spills, reactions, and exposure:

• Keep chemicals in approved containers
• Separate incompatible substances
• Store flammables safely
• Keep lids closed
• Avoid mixing chemicals
• Use spill trays or secondary containment
• Maintain ventilation
• Keep SDS accessible
• Train workers before handling chemicals

Quick Checklist: Safe chemical storage means correct labelling, compatible storage, secure containers, ventilation, spill control, and easy access to Safety Data Sheets.

Chemical Spill Response and Emergency Procedures

An effective chemical spill response protects workers and limits damage:

• Stop work if unsafe
• Alert nearby workers
• Identify the substance
• Use SDS emergency instructions
• Wear correct PPE
• Contain the spill only if trained
• Evacuate if needed
• Report and investigate the incident

A clear hazardous substance spill response plan, alongside strong chemical spill prevention measures, minimises risk before an emergency ever occurs.

Why Hazardous Substances Training Is Essential

To reduce chemical exposure risks and improve workplace compliance, workers and supervisors should understand SDS, COSHH assessments, GHS labels, PPE selection, spill response, and safe chemical handling. Our Hazardous Substances / COSHH Awareness course helps learners build practical knowledge for safer, more compliant workplaces.

This training is valuable for:

• HSE officers
• Supervisors
• Workers
• Job seekers
• Certification learners
• International workers

Hazardous Substances Prevention Checklist

• Identify all hazardous substances
• Review Safety Data Sheets
• Complete a chemical risk assessment
• Use the hierarchy of controls
• Provide correct PPE
• Train workers before exposure
• Label and store chemicals correctly
• Maintain ventilation
• Prepare spill response procedures
• Review controls regularly

Hazardous substances are common in many workplaces, but serious harm can be prevented when employers and workers understand the risks, assess exposure, apply control measures, use SDS, follow GHS labels, and complete proper training. For workers, supervisors, and safety professionals who want practical knowledge, the Hazardous Substances / COSHH Awareness course is a strong next step toward safer chemical handling and better workplace compliance.