practicable, synthetic methodologies should be designed to use and generate
substances that possess little or no toxicity to human health and the
Energy requirements should be recognised for their environmental and economic
impacts and should be minimised. Synthetic methods should be conducted
at ambient temperature and pressure.
Chemical products should be designed so that at the end of their function
they do not persist in the environment and break down into innocuous degradation
(Green Chemistry Principles, Dr. Paul Anastas et al)
chemical industry has done much to reduce the impact that production waste
has on the environment. See the minimising
for more information on this.
No matter how "clean" the production process, however, there
remains the question of what happens to a product when it is used in the
way it is intended. Fertilisers, pesticides and herbicides are, by their
very nature, always released into the environment. Domestic cleaning products
end up in the sewage system, and are discharged into rivers or the sea.
The levels at which many chemicals are present in the environment may
present no threat to human, animal or plant life. Over a longer period,
however, there may be subtle changes that have an indirect affect.
For example, the chlorinated fluorocarbons (CFCs) used in aerosols and
refrigerators presented little or no risk to human health (they are in
fact not toxic to humans). It is now generally accepted, though, that
the accumulation of these materials in the upper atmosphere has resulted
in ozone depletion, allowing a higher level of harmful ultraviolet radiation
to reach the planet surface. Their use is therefore being phased out.
Similar situations apply to "greenhouse" gases like carbon
dioxide. This is not present at anywhere near toxic levels, but increases
may be sufficient to be affecting global temperatures.