D6: Environmental impact of some medications

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

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

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)

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

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

• 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

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

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

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

• 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