5.1 Control of Substances Hazardous to Health (COSHH) & Hazardous Materials

5.1 Control of Substances Hazardous to Health (COSHH) & Hazardous Materials

Hazardous substances represent a widespread risk across construction and electrotechnical sites. Electricians routinely handle or disturb chemical agents, dusts, toxic fumes, and synthetic resins. Mastering the statutory provisions of the Control of Substances Hazardous to Health Regulations 2002 (COSHH) and the Classification, Labelling and Packaging (CLP) framework is essential for passing the ECS assessment and safeguarding long-term health.

---

The Control of Substances Hazardous to Health Regulations 2002 (COSHH)

The Control of Substances Hazardous to Health Regulations 2002 (as amended) (COSHH) require employers to control exposure to substances that cause ill health. Under COSHH, duty-holders must assess health risks, introduce preventative controls following the hierarchy of prevention, maintain extraction equipment, monitor exposure, and provide health surveillance.

Scope and Substances Covered by COSHH

COSHH regulates hazardous substances encountered in industrial and construction work:

• Chemicals: Solvents, adhesives, cleaning solutions, acids, alkalis, and lubricants.
• Dusts: Inhalable and respirable dusts, including silica from chasing or drilling.
• Fumes, Vapours & Gases: Rosin fumes from soldering flux, solvent vapours from adhesives, and battery off-gassing.
• Biological Agents: Bacteria, fungi, and viruses in unhygienic voids, sewers, or damp soil.

Excluded Substances Under Dedicated Legislation

COSHH does not cover all hazardous materials. Specific high-hazard substances are governed by dedicated statutory instruments:

• Asbestos: Regulated under the Control of Asbestos Regulations 2012 (CAR).
• Lead & Lead Compounds: Regulated under the Control of Lead at Work Regulations 2002 (CLAW).
• Ionising Radiation: Regulated under the Ionising Radiations Regulations 2017 (IRR).

---

Routes of Hazardous Substance Entry

Hazardous substances cause physiological damage only after entering biological tissues via four primary pathways:

1. Inhalation: Breathing dusts, fumes, vapours, or gases into the respiratory tract. This is the most common and rapid route of exposure on site. Respirable particulates enter lung alveoli and cross into the bloodstream.
2. Ingestion: Swallowing chemical residues through hand-to-mouth transfer when eating, drinking, smoking, or vaping with unwashed hands.
3. Skin Absorption: Direct contact where chemical agents (e.g., solvents, degreasers, resins) penetrate the skin lipid barrier into the bloodstream without an open wound.
4. Injection: Punctures caused by contaminated sharps, such as jagged cable armouring wires or discarded needles in derelict risers.

---

Acute vs Chronic Health Effects & Occupational Dermatitis

Exposure to hazardous substances generates two distinct categories of physiological harm:

• Acute Effects: Immediate reactions occurring within seconds or minutes of exposure (e.g., chemical burns, solvent dizziness, acute asphyxiation).
• Chronic Effects: Long-term illnesses resulting from repeated, cumulative exposure over months or years (e.g., occupational asthma, silicosis, organ damage).

Occupational Contact Dermatitis

Dermatitis is a prevalent inflammatory skin condition among electricians:

• Irritant Contact Dermatitis: Caused by physical or chemical abrasion stripping natural skin oils (e.g., repeated exposure to solvent cements, degreasers, or cement dust).
• Allergic Contact Dermatitis: An irreversible immune response triggered once an operative becomes sensitised to a chemical (e.g., epoxy jointing resins, nickel, or colophony). Subsequent trace exposures trigger severe eczema.

Critical Safety Rule on Barrier Creams: Barrier creams serve solely as supplementary skin-conditioning aids. Barrier creams are never a substitute for chemical-resistant gloves. They offer zero reliable protection against hazardous chemicals.

---

The CLP Regulation & Chemical Hazard Classification

Chemical classification across the UK is governed by the GB CLP Regulation. The system replaces older orange square symbols with standardised diamond-shaped hazard pictograms featuring a red border, white background, and black symbol to warn operatives of physical, health, and environmental dangers before handling products on site.

---

Safety Data Sheets (SDS) & The 16 Standard Sections

Manufacturers must supply a Safety Data Sheet (SDS) organized into 16 standardised sections for every hazardous product:

• Section 1 — Identification: Product name, manufacturer details, emergency hotline.
• Section 2 — Hazard Identification: CLP pictograms, signal words (Danger or Warning), hazard statements.
• Section 4 — First-Aid Measures: Emergency protocols for inhalation, skin/eye contact, ingestion.
• Section 7 — Handling & Storage: Safe handling practices, ventilation, storage conditions.
• Section 8 — Exposure Controls / Personal Protection: Statutory Workplace Exposure Limits (WELs) and mandatory PPE specifications (e.g., BS EN 374 gloves, BS EN 149 respirators).

---

Workplace Exposure Limits (WELs) & HSE Guidance EH40

The HSE publishes statutory Workplace Exposure Limits (WELs) in guidance document EH40:

• Long-Term Exposure Limit (LTEL): Maximum permissible airborne concentration averaged over an 8-hour Time-Weighted Average (TWA) to protect against chronic diseases.
• Short-Term Exposure Limit (STEL): Maximum permissible airborne concentration averaged over a 15-minute TWA to prevent acute irritation or narcosis from short peak exposures.

WELs are expressed in parts per million (ppm) for gases and vapours, or milligrams per cubic metre (mg/m³) for dusts and fumes.

---

Electrotechnical Hazardous Substances & Practical Controls

Common hazardous materials in electrical installations require targeted precautions:

• PVC Solvent Cements & Adhesives: Release volatile organic compounds (VOCs). Ensure cross-ventilation and wear BS EN 374 nitrile gloves.
• Degreasers & Contact Cleaners: Aerosols presenting fire and inhalation hazards. Isolate electrical supplies, eliminate ignition sources, and wear eye protection.
• Battery Electrolytes (Substations & UPS): Sulfuric acid in lead-acid cells and potassium hydroxide in NiCd cells cause severe burns. Wear chemical visors, acid aprons, and neoprene gauntlets, with eyewash access.
• Transformer Cooling Oils (Legacy PCBs): Pre-1986 transformers may contain carcinogenic Polychlorinated Biphenyls (PCBs). Never disturb suspect oil; report for specialist hazmat testing.
• Soldering Flux & Lead Solder: Rosin flux emits toxic fumes causing asthma. Solder contains toxic lead. Deploy tip LEV extraction and wash hands before meals.

---

CLP Hazard Pictograms & Electrotechnical Meanings

---

ECS Exam Focus: Spotting and Avoiding Harmful Substances

• You cannot tell by smell whether a product is harmful: many harmful substances have no smell at all.
• Recognise a hazardous substance by the hazard symbol (pictogram) on the container label.
• After a COSHH assessment, the risks and controls must be explained to the operatives using the substance.
• Bitumens, solvents, epoxy resins and cement can cause skin problems. Asbestos is extremely harmful if inhaled but does not significantly affect the skin.
• Clean very dirty hands with soap and water or a proprietary hand cleanser, never white spirit, paraffin or thinners, which strip the skin's natural oils and cause dermatitis.
• Lead usually enters the blood by swallowing it from contaminated hands, so wash before eating, drinking or smoking.
• Personal hygiene protects your own health and the health of others, including your family, from contamination you could carry home.
• Sunlight: ultraviolet rays cause sunburn and premature skin ageing, and the most serious effect is an increased chance of skin cancer. Cover up, use sunscreen and take breaks in the shade.
• Asbestos can cause asbestosis, lung cancer and mesothelioma; all types are hazardous, and suspected asbestos means stop work and report it (section 10.1).