D.6: ENVIRONMENTAL IMPACT OF SOME MEDICATIONS
UNDERSTANDINGS
- High-level waste (HLW) is waste that gives off ______________ amounts of ionizing radiation for a ___________ time.
- Low-level waste (LLW) is waste that gives off _______________ amounts of ionizing radiation for a ___________time.
- Antibiotic resistance occurs when microorganisms become resistant to antibacterials.
APPLICATION AND SKILLS
- Description of the environmental impact of medical nuclear waste disposal.
- Discussion of environmental issues related to left-over solvents.
- Explanation of the dangers of antibiotic waste from improper drug disposal and animal waste, and the development of antibiotic
resistance.
- Discussion of the basics of green chemistry (sustainable chemistry) processes.
- Explanation of how green chemistry was used to develop the precursor for Tamiflu (oseltamivir).
NATURE OF SCIENCE
- Ethical implications and risks and problems – the scientific community must consider both the side effects of medications on the
patient and the side effects of the development, production, and use of medications on the environment (i.e. disposal of nuclear
waste, solvents, and antibiotic waste).
INTRO:
- improper drug disposal = side-effects in the _______________________= potential adverse effects on ________________ health =
self-defeating
- quality of the environment is critical to the health of all living things
1. RADIOACTIVE WASTE
- associated with many forms of ____________________ treatment
- nuclear chemistry = rapidly expanding area of medicine
- an increasing problem in the drug industry
TYPE OF WASTE
HIGH-LEVEL WASTE
(HLW)
DESCRIPTION
- gives off _______________
amounts of ionizing radiation
for a _____________ time
- half-lives of associated
isotopes are ____________
EXAMPLES
- fuel rods generated by
the nuclear energy
industry
DISPOSAL METHOD
- often stored under
_______________ in
reinforced cooling ponds for
5 to 10 years; then,
- ______________(turned
into glass-like material) and
stored underground in
______________bunkers
LOW-LEVEL WASTE
(LLW)
- gives off small amounts of
ionizing radiation for a short
time
- half-lives of associated
isotopes are ____________
-___________________
used in cancer therapy
tend to be LLW (e.g.
131
I , 89 Sr , 153 Sm )
- rubber gloves
-paper towels
-protective clothing
- interim storage in safe,
secure containers
- conventional disposal (e.g.
landfill, sewer, compaction)
2. ANTIBIOTIC WASTE: ARE WE KILLING THE CURES?
SOURCES OF ANTIBIOTIC WASTE
- __________________ of unused antibiotics
- ________________ (from people taking antibiotics)
- from __________________ (in antibiotics in the food they eat…often gets discharged into rivers…?)
↑ antibiotic waste = ____ antibiotics in microorganisms found in soil/water = ____ antibiotic resistance = ____ efficacy
3. SOLVENT WASTE
- many different organic solvents used in the production of drugs (the major emission of the drug industry)
- disposal of solvents often involves ________________________, which can release toxins into the environment – it is
therefore a serious concern of the pharmaceutical industry
*Suitability of Solvents can be assessed by three factors:
FACTOR
POTENTIAL CONCERNS
1. _______________ to - carcinogenic? ; other health concerns? (e.g. chlorinated and aromatic compounds , ethers)
workers
2. ______________ of
- flammable?; explosive?, toxic by-products
the process
3. harm to the
- contaminate soil/water?; ozone depletion?; greenhouse gas formation when released or
___________________ burned?; recyclable?
SOLVENT TYPE
CHLORINATED
DISPOSAL
- __________________ at very high temperatures (to prevent
formation of carcinogenic dioxins)
Examples
- dichloromethane,CH2Cl2
- tetrachloromethane, CCl4
NON-CHLORINATED
(preferred)
- may be recycled or burned for energy
- disposed in rivers/sea if harmless (e.g. sodium chloride)
- ethanol, C2H5OH
- propan-2-ol, CH3CH(OH)CH3
- propanone
- ethyl ethanoate
4. GREEN CHEMISTRY
- Discussion of the basics of green chemistry (sustainable chemistry) processes.
BASICS OF GREEN (SUSTAINABLE) CHEMISTRY
FOCUS AIMS:
- reducing harm to the environment by minimizing the use and
generation of hazardous substances
- prevent _______________
- reducing pollution at its ______________
- reduce the footprint of chemical manufacturing processes
- improve product and environmental safety
*Particularly important in the pharmaceutical industry which
often involves the production of many polluting substances.
*Some Important Factors to consider when designing new drugs:
FACTOR / AIM
DESCRIPTION
1. MAXIMIZING REACTANT
DEFINED: the ratio of the total mass of the ________________products to the total mass
of the products (i.e. a measure of how much of the reactants remain in the final product)
TO DESIRED PRODUCT
*The formula for calculating atom economy is in Data Booklet.
CONVERSION
(a) ATOM ECONOMY
% ATOM ECONOMY =
molar mass of desired product
x 100
molar mass of all reac tan ts
*goal = 100% = no atoms are wasted
(b) ENVIRONMENTAL FACTOR
ENVIRONMENTAL FACTOR (E – factor) =
total waste (kg)
desired product (kg)
(c) CARBON EFFICIENCY
CARBON EFFICIENCY =
amount of carbon in product
total amount of carbon present in reac tan ts
2. NUMBER OF STEPS IN
SYNTHESIS
- _____________________ number of steps
- In General: ↑ # of steps = ↓ % yield = ↑ waste = ↑ energy use
3. TYPE OF SOLVENTS AND
REACTANTS
- use green and safer solvents whenever possible
- Consider: energy and materials needed to manufacture solvent; disposal issues?...can
solvent be recycled?; safety / toxicity to workers?
EXAMPLE:
OBTAINING THE TAMIFLU (oseltamivir) PRECURSOR: A GREEN CHEMISTRY CASE STUDY
- Explanation of how green chemistry was used to develop the precursor for Tamiflu).
PROBLEM
*OBTAINING PRECURSOR
(shikimic acid)
DESCRIPTION OF PROBLEM
*starting material = _______________
acid = ___________________ to
Tamiflu = isolated from Chinese star
_______________ plant = low [shikimic
acid] = very low ________________ =
_______ stage process to extract = 1
______ to complete = uneconomical and
‘ungreen’.
PURIFICATION PROCESS
USE OF UNSAFE, TOXIC
CHEMICALS
SMALL YIELDS
- used chromatography to purify
- lithium nitride, LiN (unsafe)
- azides (e.g. NaN3)
- e.g. 0.0004 % from anise plant
GREEN CHEMISTRY SOLUTION
- obtain shikimate (salt of the acid) from
fermentation reactions of genetically
engineered __________________
- harvest shikimate for the needles of
several varieties of ______________
trees (low yield, but plentiful source)
- extraction of shikimate from
suspension cultures of the Indian
sweetgum tree (inexpensive and does
not involve genetic manipulation)
- used greener recrystallization
- biodegradable, less toxic
- much higher via bioengineering
methods
*Main problem
PRACTICE QUESTION: ATOM ECONOMY
1. Deduce the percentage atom economy for the following nucleophilic substitution reaction:
CH3(CH2)3OH + NaBr + H2SO4  CH3(CH2)3Br + H2O + NaHSO4
YOUTUBE:
-GREEN CHEMISTRY (Berkeley students) https://www.youtube.com/watch?v=czt7qi_EFtk