10.3 Chemical and Biological Hazards: USECHH, CLASS, Silica, Asbestos, Lead and Site Infections
Key Takeaways
USECHH 2000 requires employers to keep a register of chemicals hazardous to health, have a chemical health risk assessment carried out by a registered assessor, and act on its recommendations within one month.
USECHH regulation 15 sets the control order: elimination, substitution, total enclosure, isolation, process modification, engineering control equipment, safe work systems and, last, approved personal protective equipment.
Asbestos, benzene, free crystalline silica, isocyanates and lead are listed in Schedule II of USECHH 2000 as chemicals for which medical surveillance is appropriate, at intervals of no more than 12 months.
The OSH (Prohibition of Use of Substance) Order 1999 prohibits the use of crocidolite (blue asbestos) for all purposes except research or analysis.
Leptospirosis, viral hepatitis and pneumoconioses such as silicosis and asbestosis are listed occupational diseases in the Third Schedule of NADOPOD 2004, reportable within 7 days.
How chemicals harm
Chemicals enter the body by:
- inhalation: dusts, fumes, vapours and gases. This is the main route on construction sites.
- skin contact: cement, solvents and epoxy resins
- ingestion: eating or smoking with contaminated hands
- injection: high-pressure fluid or cuts
Effects may be:
- acute: burns, poisoning, asphyxiation, dizziness
- chronic: silicosis, asbestosis and mesothelioma, cancer, nerve damage, sensitisation (dermatitis, occupational asthma)
USECHH 2000: the employer's duties
The OSH (Use and Standards of Exposure of Chemicals Hazardous to Health) Regulations 2000 apply wherever chemicals hazardous to health are used.
| Duty | Regulation | Requirement |
|---|---|---|
| Register | 5 | Identify and record all chemicals hazardous to health used at the workplace; keep the register updated and accessible to exposed employees |
| Exposure limits | 6–8 | Exposure must not exceed the permissible exposure limits (ceiling limits and 8-hour time-weighted averages) |
| Assessment of risk to health (CHRA) | 9–12 | Carried out by a registered assessor; reviewed after a significant change, after five years, or when DOSH directs |
| Action | 14 | Carry out the recommended actions within one month of receiving the report; reduce exposure below the PELs, or to the lowest practicable level |
| Controls | 15 | In order: elimination; substitution; total enclosure; isolation; process modification; engineering control equipment; safe work systems; approved PPE. Safe work systems are documented and reviewed |
| PPE | 16 | Approved PPE only where other controls are impracticable, as an interim measure, or as a top-up; suitable, fitted, issued, maintained, with training |
| Engineering control equipment | 17–19 | Inspected at least monthly; examined and tested by a hygiene technician at least every 12 months; local exhaust ventilation designed and tested by a registered Professional Engineer; records kept |
| Labelling | 20–21 | Containers labelled; relabelled if labels are lost or contents are decanted |
| Information and training | 22–24 | Workers told the risks, precautions, and monitoring and surveillance results |
| Safety data sheets | 25 | Available at the workplace |
| Exposure monitoring | 26 | By a hygiene technician where the assessment requires it (gas and oxygen checks before confined space entry excepted); Schedule II chemicals at least every six months; personal records kept 30 years |
| Health surveillance | 27 | By an occupational health doctor; Schedule II chemicals at least every 12 months; records kept 30 years |
| Medical removal | 28 | Remove workers at increased risk, including pregnant or breastfeeding employees on medical advice |
| Warning signs | 29 | At entrances to hazardous areas, in Bahasa Malaysia and English, dark red on white |
Schedule II, chemicals for which medical surveillance is appropriate, includes asbestos, benzene, free crystalline silica, isocyanates, lead and its compounds, cadmium and arsenic, among others.
CLASS 2013: labels and safety data sheets
The OSH (Classification, Labelling and Safety Data Sheet of Hazardous Chemicals) Regulations 2013 put the UN Globally Harmonized System (GHS) into Malaysian law, with the detail in DOSH's ICOP on chemical classification and hazard communication.
- Classification: the principal supplier classifies each chemical.
- Label: the label shows the product identifier, supplier identification, signal word ("Danger" or "Warning", never both), hazard statements, pictograms (a black symbol on a white background in a red-bordered diamond) and precautionary statements, in Bahasa Malaysia and English (regulations 8 and 9).
- Safety data sheet: the supplier provides an SDS with 16 headings in a fixed order, in both languages, and revises it when new information appears or every five years (regulation 13).
On site the SSS checks that every chemical has a label and an SDS before use, that decanted containers are labelled, and that the SDS information on PPE, storage, spills and first aid is followed.
Construction chemical hazards
| Hazard | Where it arises | Health effect | Key controls |
|---|---|---|---|
| Wet cement and concrete | Concreting, plastering, mortar | Alkaline burns; irritant and allergic dermatitis | Gloves, boots, long sleeves; washing facilities; skin care; report dermatitis (NADOPOD) |
| Respirable crystalline silica | Cutting, drilling, chasing, grinding, breaking concrete, block, brick or stone; dry sweeping | Silicosis, lung cancer, COPD | Water suppression or on-tool extraction; vacuum cleaning instead of dry sweeping; respirators to the CHRA; health surveillance (Schedule II) |
| Asbestos | Old roof sheets, ceiling boards, pipe lagging, floor tiles in refurbishment or demolition | Asbestosis, lung cancer, mesothelioma, often decades later | Survey before work; do not disturb; specialist removal under DOSH's 2017 guidelines; crocidolite prohibited (1999 Order); scheduled waste disposal |
| Lead | Removing old lead paint by burning or blasting; cutting coated steel | Lead poisoning, affecting nerves, kidneys, blood and reproduction | Avoid hot work on lead paint; wet methods; extraction; hygiene; health surveillance |
| Solvents | Paints, thinners, adhesives, cleaning, especially in confined areas | Dizziness, narcosis, liver and nerve damage; fire | Water-based substitutes; ventilation; confined space controls; no ignition sources |
| Isocyanates and epoxies | Polyurethane coatings, sealants, foams, epoxy resins | Occupational asthma, skin sensitisation | Substitution; supplied-air or suitable respirators when spraying; gloves; health surveillance |
| Welding and cutting fumes | Steelwork, rebar welding, galvanised steel | Metal fume fever, lung irritation, long-term effects | Fume extraction; ventilation; respiratory protection (Section 9.2) |
| Diesel exhaust | Plant and generators in basements and tunnels | Irritation, lung disease; carbon monoxide poisoning | Keep engines outside; ventilation; maintenance |
| Wood dust | Formwork cutting, carpentry | Irritation, asthma; some hardwood dusts cause cancer | Extraction on saws; respiratory protection |
| Bitumen and torch-on membranes | Roofing, waterproofing | Burns, fumes, fire | Hot work permit; ventilation; PPE |
Pneumoconioses (silicosis, asbestosis) and occupational dermatitis appear in the NADOPOD Third Schedule. A diagnosed case must be reported within 7 days on form JKKP 7.
Biological hazards on construction sites
| Hazard | Source | Controls |
|---|---|---|
| Leptospirosis | Bacteria in rat urine, contaminating water, mud and soil in excavations, drains and flooded areas | Rodent control; good waste management; cover cuts; gloves and boots; washing facilities; early treatment if flu-like illness follows exposure |
| Dengue | Aedes mosquitoes breeding in stagnant water in containers, tyres, roof slabs and lift pits | Remove standing water daily; inspect for breeding; cooperate with health authority inspections (Destruction of Disease-Bearing Insects Act 1975); repellents |
| Tetanus | Puncture wounds from nails and rusty metal | Remove projecting nails (CDM regulation 20); first aid; tetanus vaccination |
| Hepatitis A and gastro-enteritis | Sewage, contaminated water and food | Clean drinking water; toilets and handwashing (CDM Second Schedule); hygiene |
| Legionella | Stagnant water in tanks, cooling systems and hoses | Flush and disinfect water systems; avoid spraying stagnant water |
| Tuberculosis and other respiratory infections | Crowded worker accommodation | Housing standards (Act 446); ventilation; health screening |
| Bird and bat droppings | Old roofs and plant rooms during refurbishment | Damp down before removal; respiratory protection |
DOSH's 2015 excavation bulletin lists leptospirosis, gastro-enteritis, hepatitis A and tetanus as health hazards for groundworkers. Leptospirosis and viral hepatitis are listed in the NADOPOD Third Schedule for relevant work.
Scenario: chasing walls in a refurbishment
Electricians are cutting chases in brick walls with dry angle grinders in an enclosed corridor of a 1980s building. The dust is visible, and the ceiling boards above are a grey fibrous material. The SSS:
- Stops the cutting, and keeps everyone out until the dust settles and is cleaned up with an H-class vacuum, not by sweeping.
- Suspends work near the ceiling boards and arranges an asbestos survey. If asbestos is present, removal follows DOSH's 2017 guidelines, including DOSH acknowledgement, before the boards are disturbed.
- Requires silica controls for the chasing: wall chasers with on-tool extraction, or wet cutting where electrics allow, plus respiratory protection specified by the CHRA. Ensures the chemicals register and CHRA cover silica, and that health surveillance follows Schedule II.
- Briefs the electricians on why "just a bit of dust" can cause silicosis years later.
Under USECHH 2000, within what period must an employer carry out the control actions recommended in a chemical health risk assessment report?
Within one month of receiving the report
Within one year of receiving the report
Before the next five-yearly review
Only when DOSH issues an improvement notice
Which substance is prohibited for all purposes except research or analysis by the OSH (Prohibition of Use of Substance) Order 1999?
Portland cement
Crocidolite (blue asbestos)
Diesel fuel
Water-based acrylic paint
Following USECHH regulation 15, which control should an SSS consider first for silica dust from cutting concrete blocks?
Issuing disposable dust masks to every worker
Posting warning signs around the cutting area
Eliminating the cutting by ordering blocks to size
Rotating workers so each cuts for less time
Sections you finish are checked off in the contents.