D6: Environmental impact of some medications

Question 1

Define ionising radiation

Answer 1

IONISING RADIATION: when radioactive isotopes (radioisotopes) undergo radioactive decay to form ions

Question 2

Define radioactive waste

Answer 2

RADIOACTIVE WASTE: byproduct of radioisotopes that can be categorised into low-level waste (LLW) and high-level waste (HLW)

Question 3

Distinguish between low-level nuclear waste and high-level waste

Answer 3

LOW-LEVEL WASTE: low activity and short half-life (Eg. Objects contaminated by radioactive material or exposed to radioactivity)

HIGH-LEVEL WASTE: high activity and long half-life (Eg. Materials from nuclear reactors)

Question 4

Explain how low-level waste and high-level waste are differently disposed

Answer 4

LOW-LEVEL WASTE:
- Stored onsite until decayed to an extent where it can be disposed of as ordinary waste
- Incinerated to reduce volume and distribute radioisotopes over a large area
- Buried underground in concrete bunkers/concrete-lined vaults

HIGH-LEVEL WASTE:
- Converted to glass (vitrification) for easier storage before being stored in storage pools underwater to cool, before being transferred to dry storage casks in concrete bunkers deep underground

Question 5

State some Pharmacologically Active Compounds (PAC)

Answer 5

Pharmacologically Active Compounds (PACs):
- Antibiotics
- Analgesics
- Steroids/hormones
- Chemotherapy drugs

Question 6

State the sources of PACs

Answer 6

• Incorrect disposal of drugs in hospitals/pharmacological industries
• Incorrect disposal of waste products from pharmacological industries (Eg. Organic and chlorinated solvents)
• Use of antibacterial drugs in agriculture/animal husbandry

Question 7

State the effects of PACs

Answer 7

• Antibiotic resistance
• Mutations in living organisms
• Environmental problems
  (chlorinated solvents cause ozone depletion and produce greenhouse gases)

Question 8

State an alternative to chlorinated solvents

Answer 8

Supercritical fluids: no phase boundary between liquids and gases and behave as both

Question 9

Explain what green chemistry is

Answer 9

GREEN CHEMISTRY: 12 principled approach to chemical research and chemical industrial processes that minimise the production of hazardous substances and their release into the environment

• Maximise atom economy (reduce waste by converting as much of the starting materials as possible into useful products)
• Less hazardous chemical syntheses
• Design for energy efficiency

Question 10

Explain how green chemistry changed the process of synthesising oseltamivir

Answer 10

• Total synthesis from petrochemical starting materials: requires huge amounts of materials and generates large amounts of waste
• Current commercial synthetic route: uses shikimic acid (naturally occurring renewable material either extracted from Chinese star anise or obtained from glucose by fermenting genetically modified bacteria)
• Shikimic acid from star anise: low yield and dependent on the availability of star anise
• Shikimic acid from GM bacteria: better long-term solution due to low temperature of fermentation and use of an aqueous medium