QUESTION 1

(a) Handling operations for solid/powder substances are often a source of dust generation and are a source of exposure to hazardous substances in industries. Describe in details the measures that can be taken to prevent exposure during the following situations

• Selection of materials
• Bulk powder delivery and transfer
• Dust generation at powder handling processes

(b) Discuss the four main mechanisms by which deposition of particles in the respiratory system may occur

(c) Discuss briefly on the two particle size fractions of interest in the workplace

QUESTION 2

(a) What are the four main stages of toxicokinetics?

(b) What are the main objectives of xenobiotic metabolism?

(c) Discuss in details the principles of biotransformation differentiating clearly the phases involved. Illustrate your answer with a relevant example

(d) Briefly discuss the four routes of excretion of hazardous substances from the body

QUESTION 3

(a) Discuss in details on four possible routes of entry of hazardous substances inside the body

(b) Graphically illustrate the Dose-Response Relation. Briefly discuss the following points on the dose-response curve

• The No-effect level
• The Threshold-dose
• Lethal Dose 50% and Lethal Concentration 50%
• Toxic Dose 50% and Toxic Concentration 50%

QUESTION 4
(a) Describe the following combined effects that may occur in the workplace on exposure to hazardous substances. Support your answer with relevant example of such substances

The combine effects are as follows-

• Additive effects
• Synergistic effects
• Potentiation
• Antagonism
• Independent

(b) Discuss on three allergic conditions that can occur on exposure to chemical substances that can lead to respiratory sensitization. Support your answer with an example of such substances

(c) Briefly describe on the causes and symptoms of acute irritation of the upper and lower respiratory tract