NEBOSH Workplace Hazards 5

Question 1

What are the main routes of entry for hazardous substances into the body?

Accepted Answer

Inhalation (main route), skin absorption, ingestion, and injection

Answer

Inhalation is the most significant route for most occupational chemical exposures because the lungs have a large surface area and rich blood supply for rapid absorption. Skin absorption is important for some chemicals (organophosphates, isocyanates, solvents). Ingestion (hand-to-mouth) occurs from contaminated surfaces. Injection (needlestick, high-pressure equipment) is rare but serious.

Question 2

What is the purpose of health surveillance for workers exposed to occupational hazards?

Accepted Answer

To detect early signs of occupational ill health so that action can be taken before irreversible damage occurs

Answer

Occupational health surveillance (audiometry, lung function testing, skin assessments, biological monitoring, HAVS assessment) is targeted at specific exposure groups to detect early signs of work-related disease. Early detection allows removal from exposure, preventing progression to irreversible disability.

Question 3

A worker presents with sudden loss of consciousness after entering a sewer manhole. What is the most likely cause?

Accepted Answer

Hydrogen sulphide (H₂S) toxicity or oxygen deficiency — both can cause instantaneous unconsciousness

Answer

H₂S is produced by organic decomposition in sewers. At concentrations above 100 ppm, it rapidly paralyses the sense of smell and causes near-instantaneous loss of consciousness and death. Oxygen deficiency occurs as organic matter consumes oxygen. Rescuers must never enter without confined space entry procedures — 60% of confined space deaths are rescuers.

Question 4

What are 'threshold limit values' (TLVs) and who develops them?

Accepted Answer

TLVs are occupational exposure guidelines for airborne chemical concentrations developed by the American Conference of Governmental Industrial Hygienists (ACGIH)

Answer

TLVs are published annually by ACGIH based on the best available toxicological and epidemiological evidence. They include TLV-TWA (8-hour average), TLV-STEL (15-minute peak), and TLV-C (ceiling — never exceeded). Many countries use TLVs as the basis for their legally enforceable OELs. Gulf states use a combination of ACGIH TLVs and national OELs.

Question 5

What is the health risk of working with lead in construction or industrial settings?

Accepted Answer

Lead is absorbed by inhalation and ingestion, causing lead poisoning: neurological damage, anaemia, renal damage, reproductive toxicity, and in children, permanent intellectual impairment

Answer

Lead (in old paint, solder, battery manufacturing, traditional pottery) is absorbed by inhalation of dust/fumes and hand-to-mouth ingestion. It accumulates in blood, bones, and organs. Effects: neurological damage (adults and children), anaemia, hypertension, renal disease, and reproductive toxicity. Children are especially vulnerable to intellectual impairment.

NEBOSH IGC Practice Test

NEBOSH IGC Practice Test

NEBOSH Workplace Hazards 5