Q: A factory worker is exposed to benzene at a concentration of 2 ppm for 8 hours per day. The permissible exposure limit (PEL) for benzene is 1 ppm as an 8-hour time-weighted average (TWA). Which equation should be used to determine if the worker's exposure exceeds the PEL?

Use $$\text{TWA} = \frac{C_1$ \times T_1$ + C_2$ \times T_2$ + \ldots + C_n \times T_n}{T_1$ + T_2$ + \ldots + T_n}$$

Q: A chemical has a TLV of 50 ppm. If a worker is exposed to 40 ppm for 4 hours and 60 ppm for 4 hours, what is the worker's 8-hour TWA exposure?

$$\text{TWA} = \frac{(40 \times 4) + (60 \times 4)}{8} = \frac{160 + 240}{8} = \frac{400}{8} = 50$$ ppm

Q: A worker is exposed to a radioactive source emitting 0.5 mSv/hr for 8 hours. What is the total dose received?

$$\text{Dose} = 0.5 \ \text{mSv/hr} \times 8 \ \text{hr} = 4 \ \text{mSv}$$

Question 1

Which of the following best describes the purpose of an exposure limit in industrial hygiene?

Accepted Answer

To define the concentration of a hazardous substance in workplace air below which nearly all workers may be repeatedly exposed without adverse effects.

Question 2

A factory worker is exposed to benzene at a concentration of 2 ppm for 8 hours per day. The permissible exposure limit (PEL) for benzene is 1 ppm as an 8-hour time-weighted average (TWA). Which equation should be used to determine if the worker's exposure exceeds the PEL?

Accepted Answer

Use $$	ext{TWA} = \frac{C_1$ 	imes T_1$ + C_2$ 	imes T_2$ + \ldots + C_n 	imes T_n}{T_1$ + T_2$ + \ldots + T_n}$$

Question 3

Which of the following is NOT a common type of exposure limit used in occupational health?

Accepted Answer

LD50 (Lethal Dose 50%)

Question 4

A chemical has a TLV of 50 ppm. If a worker is exposed to 40 ppm for 4 hours and 60 ppm for 4 hours, what is the worker's 8-hour TWA exposure?

Accepted Answer

$$	ext{TWA} = \frac{(40 	imes 4) + (60 	imes 4)}{8} = \frac{160 + 240}{8} = \frac{400}{8} = 50$$ ppm

Question 5

Which of the following best describes the difference between acute and chronic health effects?

Accepted Answer

Acute effects occur immediately after exposure, while chronic effects develop over a long period of repeated exposure.

Question 6

Which of the following is a primary route of exposure for airborne contaminants in the workplace?

Accepted Answer

Inhalation

Question 7

A worker is exposed to a mixture of three chemicals with the following exposure fractions: Chemical A: 0.4, Chemical B: 0.3, Chemical C: 0.5. According to the additive formula for mixed exposures, does the worker exceed the combined exposure limit?

Accepted Answer

Yes, because $$0.4 + 0.3 + 0.5 = 1.2 \u003e 1$$

Question 8

Which of the following is a significant advantage of using engineering controls over personal protective equipment (PPE) in hazard management?

Accepted Answer

Engineering controls eliminate the hazard at its source, reducing reliance on worker behavior.

Question 9

Which of the following is NOT a common symptom of acute radiation sickness?

Accepted Answer

Chronic fatigue

Question 10

Which type of ionizing radiation is most likely to cause damage to DNA due to its high energy and penetration ability?

Accepted Answer

Gamma rays

Question 11

A worker is exposed to a radioactive source emitting 0.5 mSv/hr for 8 hours. What is the total dose received?

Accepted Answer

$$	ext{Dose} = 0.5 \ 	ext{mSv/hr} 	imes 8 \ 	ext{hr} = 4 \ 	ext{mSv}$$

Question 12

Which of the following best describes the function of DNA repair genes in cancer prevention?

Accepted Answer

They correct mutations that occur during DNA replication, reducing the risk of cancer.

Question 13

Which of the following is a characteristic of a malignant tumor?

Accepted Answer

It invades surrounding tissues and can metastasize to distant sites.

Question 14

Which of the following is a common screening method for early detection of cancer?

Accepted Answer

Mammography

Question 15

Which of the following statements about oncogenes is correct?

Accepted Answer

Oncogenes are mutated forms of normal genes that promote uncontrolled cell growth.

Question 16

Which of the following is NOT a category in the IARC classification of carcinogens?

Accepted Answer

Group 4: Definitely not carcinogenic to humans

Question 17

A worker is exposed to noise levels of 90 dB for 2 hours, 80 dB for 4 hours, and 70 dB for 2 hours. Using the equal energy principle, which exposure contributes most to the risk of hearing loss?

Accepted Answer

90 dB for 2 hours, because higher intensity has a greater impact even for shorter duration.

Question 18

Which of the following is a limitation of using administrative controls to reduce workplace hazards?

Accepted Answer

They rely on consistent worker compliance and may not eliminate the hazard.

Question 19

Which of the following best describes the concept of risk assessment in occupational health?

Accepted Answer

It is the process of evaluating the likelihood and severity of adverse health effects resulting from exposure to hazards.

Industrial Hygiene, Radiation, and Cancer: Study Notes for Personal Health

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