CIH Toxicology & Health Risk Assessment 1

Question 1

LD50 is defined as the dose that causes death in what percentage of a test population?

Accepted Answer

50%

Answer

LD50 (Lethal Dose 50) is the dose required to kill 50% of a test population under specified conditions.

Question 2

Which dose-response model assumes there is NO safe threshold for carcinogenic chemicals?

Accepted Answer

Linear non-threshold (LNT) model

Answer

The linear non-threshold (LNT) model assumes any dose of a carcinogen carries some risk, with no exposure level being completely safe.

Question 3

What does the term 'carcinogen' specifically describe?

Accepted Answer

A substance capable of causing cancer

Answer

A carcinogen is any substance or agent that can cause or promote the development of cancer in living tissue.

Question 4

OSHA Permissible Exposure Limits (PELs) are based on which exposure duration?

Accepted Answer

8-hour time-weighted average (TWA)

Answer

OSHA PELs are primarily established as 8-hour time-weighted averages (TWA) corresponding to a standard workday.

Question 5

Which route of chemical exposure is most common in occupational settings?

Accepted Answer

Inhalation

Answer

Inhalation is the most common route of occupational exposure because workers breathe airborne contaminants throughout their work shift.

CIH - Certified Industrial Hygienist Exam Practice Test