NEBOSH Chemical Hazards

Question 1

What is the UN Globally Harmonized System (GHS) of Classification and Labelling of Chemicals?

Accepted Answer

An internationally standardized system for classifying chemical hazards and communicating them through standardized labels (pictograms, signal words, hazard and precautionary statements) and Safety Data Sheets

Answer

UN GHS standardizes chemical hazard classification and communication globally, replacing the previous patchwork of national systems. It defines: hazard classes and categories, standardized pictograms (skull, flame, corrosive), signal words (Danger/Warning), hazard statements (H-phrases), and precautionary statements (P-phrases) on labels and Section 2 of the 16-section SDS.

Question 2

What are the main health effects of solvent exposure in the workplace?

Accepted Answer

Central nervous system depression (dizziness, headache, unconsciousness), liver and kidney damage from chronic exposure, dermatitis from skin defatting, and carcinogenicity for some solvents

Answer

Organic solvents (toluene, xylene, acetone, chlorinated solvents, n-hexane) are absorbed via inhalation and skin. Acute CNS effects: dizziness, impaired judgment, unconsciousness. Chronic effects: peripheral neuropathy (n-hexane), liver/kidney damage (chlorinated solvents), leukaemia (benzene — Group 1 carcinogen). Skin contact causes irritant contact dermatitis.

Question 3

What is the correct control hierarchy for chemical exposures in the workplace?

Accepted Answer

Elimination, substitution with less hazardous substance, engineering controls (enclosure, LEV), administrative controls (reducing time, rotation), PPE — as last resort

Answer

The COSHH hierarchy for chemical control: 1) Eliminate the hazardous substance (change process), 2) Substitute with less hazardous substance, 3) Engineering controls (enclosed process, local exhaust ventilation capturing contaminant at source), 4) Administrative controls (job rotation, reduced hours), 5) PPE (respiratory protection, gloves, protective clothing). Higher controls provide more reliable protection.

Question 4

What is 'local exhaust ventilation' (LEV) and what is its purpose?

Accepted Answer

A system that captures airborne contaminants at or near the point of generation before they disperse into the general workplace air — more effective than general dilution ventilation

Answer

LEV captures dust, fumes, vapours, and mist at the source using a hood or enclosure, transporting them through ductwork to filtration and safe discharge. Capture at source prevents worker exposure. LEV must be designed for the specific contaminant and process, regularly inspected, and tested (thorough examination and testing at least every 14 months under COSHH Regulations).

Question 5

What are the GHS pictogram requirements for a substance classified as acutely toxic (category 1)?

Accepted Answer

Skull and crossbones (GHS06) with signal word 'Danger'

Answer

GHS acutely toxic substances (categories 1–3, highest toxicity) carry the skull and crossbones pictogram (GHS06) with the signal word 'Danger.' Category 4 (lower toxicity) uses the exclamation mark (GHS07) with 'Warning.' Categories 1–3 require urgent medical treatment on exposure.

NEBOSH IGC Gulf Practice Test

NEBOSH IGC Gulf Practice Test

NEBOSH Chemical Hazards