Natural organic chlorine compounds
Chlorine and its compounds are natural components of the Earth - as every element has its place in biosynthesis, so it is with chlorine too.
Therefore, it is little wonder that almost 2% of
chlorine contained in the oceans as well as
bromine and iodine, is utilised
by numerous sea organisms (algae, shelp, microbes and
Almost 5 million
tonnes of methyl chloride, 0.3 million tonnes of
methyl bromide and 1.3 million tonnes of methyl iodide which occur
naturally in the sea each year, as well as large tonnages of
various other poly-halogenated methane derivatives, including
chloroform and carbon
tetrachloride, far exceed the industrially manufactured
amounts of these chemicals.
In addition, chlorine is brought in by oceanic
aerosols, volcanoes and weathering. It is also
produced and utilised on the land, both by numerous soil
microbes and worms, and by higher plants
to synthesise organic chlorine compounds. So far
some 4,000 naturally-produced organohalogen
chemicals have been identified and there are
currently hundreds of new organohalogen compounds pending
Besides simple structures like methyl chloride, nature
generates complex chlorinated molecules which can contain very high
amounts of chlorine. Even "typical industrial" organic chlorine
compounds such as pentachlorophenol, polychloropyrols,
polychlorinated biphenyls (PCB) and even tetrachlorodibenzodioxins
(TCDD) have been identified as naturally-formed substances
which have also been detected in 8,000 year old sediments. Industry
learned from nature to utilise chlorine compounds in health
protection, for example as antibiotics.
Global emission of organic chlorine compounds
from natural sources is high: many millions of
Large amounts of naturally-occurring chlorine-containing
humus elements are components of marshy wetland and rivers left in
their natural state. Data evolution shows a reduction in the
anthropogenic discharge of organochlorines into the Rhine river of
80 to 90% over the period from 1986 until the present. The present
levels in the Rhine are, therefore, close to natural background
levels. The emissions of organochlorines from nature are evenly
spread, which implies low local concentration.
In global terms, the annual natural production of organic
chlorine compounds is much greater than that of industry. In
nature, various mechanisms to control and degrade chlorine
compounds exist. For example dehalogenation, hydrolysis, photolysis
and biodegradation. The end results of these processes are mostly
chlorides such as hydrogen chloride and common salt.
Modern environmental research is intensely concerned with
gathering information on the process and intermediate products
resulting from breakdown of organic chlorine compounds, whether
they are of natural or industrial origin.
Euro Chlor encourages further research in this area in
order to learn from nature how chlorinated compounds are formed and
metabolised. Research can also help identify new chemical compounds
which have and will continue to play a key role in the progress of
Are chlorine derivatives strictly man-made?
Chlorine is naturally present as organic compounds in the sea, in
rivers and in plants.
The natural production of organic chlorine compounds actually
exceeds that of industry, and is essential to many forms of health
protection. It is important to identify how nature recycles
chlorine and uses it to create new compounds, so that industry can
learn from nature and implement this in its production
Last update: 09/2011