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The international chemicals industry is fast gearing up to replace chlorofluorocarbons
(CFCs) with ‘ozone friendly’ hydrofluorocarbons (HFCs) and hydrochlorofluorocarbons
(HCFCs). CFCs are widely used in refrigeration, in the production of plastic
foam and as aerosol propellants. Negotiations in London in July produced
an international agreement that CFCs should be phased out completely by
the year 2000, with a 50 per cent cut by 1995 and an 85 per cent cut by
1997 (This Week, 7 July).

Du Pont, the American manufacturer, expects to spend $1 billion on the
development of CFC alternatives by the end of the century. According to
a company spokeswoman, Du Pont will have spend $240 million of the total
by the end of this year; almost half the sum has gone on three new production
plants, in the US, Canada and Britain. These should all be in operation
by next month. In June, the company announced plans for four more plants:
two in the US, in Texas and in Kentucky; one in Japan and another in the
Netherlands. ICI, the British manufacturer, has spent 75 million Pounds
(pds) on a plant in the US, in Louisiana, and 30 million pds on a plant
in Runcorn, Cheshire. Both are due to come on stream from the end of this
year (‘The race to heal the ozone hoole, ¿ìè¶ÌÊÓƵ, 16 June). Within
about two years, says an ICI spokesman, the industry will be producing 100,000
tonnes of CFC substitutes per year.

Currently, the industry produces about 1 million tonnes of CFCs per
year to meet a demand that is expected to rise rapidly in the next century
as refrigeration equipment is increasingly used by populous developing nations,
such as India and China. Virtually all of the chemicals produced escape
into the atmosphere eventually; manufacturers have been making CFCs for
more than 50 years but there is now only about 2 years worth of production
still in use, estimates Archie McCulloch, an environmental scientist at
ICI Chemicals and Polymers. By the early part of the next century, industry
expects HFCs and HCFCs to meet 40 per cent of the demand for CFCs; non fluorocarbon
substitutes, such as ammonia, water and air, should meet 30 per cent and
recycling of spent chemicals should meet the rest.

With the introduction of CFC substitutes and an increasing awareness
of the damage that chemicals can do to the environment, a smaller proportion
of fluorocarbons will be allowed to escape into the atmostphere – but the
amount will still be large. Early next century, even at current levels of
production, around 400,000 tonnes of CFC substitutes are likely to be released
each year, and yet little is known for certain about the effects they will
have on the environment.

CFCs are a problem because they are so inert that they reach the stratosphere
before being broken down by ultraviolet radiation from the Sun. When this
finally happens, they release chlorine in a form that damages the ozone
layer about 20 kilometres above the Earth. The CFC substitutes, however,
get broken down in the troposphere, the lowest 8 to 16 kilometres of the
atmosphere. Also, irrespective of their effect on the ozone layer, both
types of fluorocarbons are ‘greenhouse’ gases that contribute to global
warming (Science, 8 September).

The reason for the inertness of CFCs is the complete halogenation of
their molecules: strong bonds between carbon and halogen atoms of chlorine
or fluorine replace the links in hydrocarbons between carbon and hydrogen
atoms. HFCs and HCFCs, however, have at least one hydrogen in each molecule
that can be displaced easily by reactive chemicals in the trophosphere,
known as hydroxyl free radicals. This precipitates the break down of the
entire molecule. (A radical, or free radical, is an uncharged atom or group
of atoms possessing normally one, sometimes more, unpaired electrons.)

Although the HCFCs also contain chlorine, the fact that they are destroyed
in the trophosphere means that little chlorine reaches the stratosphere
to damage the ozone layer; HFCs contain no chlorine at all, and thus are
assumed to have no capacity to damage the ozone. But the instability of
these chemicals in the troposphere may create new problems as the cocktail
of their breakdown products rains back to Earth. According to Eric Banks,
professor of fluorine chemistry at the University of Manchester Institute
of Science and Technology, ‘industry is rushing headlong into production
of these new chemicals, in almost complete ignorance of their degradation
by-products or their effects in the biosphere’.

Hydroxyl radicals (HOÄ‹), formed as a result of complex atmospheric reactions
initiated by ozone, are the dominant agent in the breakdown of HFCs and
HCFCs; nitrate radicals (NO₃Ä‹) also have a role, which is still
to be determined, but is of much less significance. Though the concentration
of hydroxyl radicals in the troposphere is just one part in 10 million million,
it is sufficient to enable them to help to rid the atmosphere of pollutants,
such as carbon monoxide, methane and other hydrocarbons, which they oxidise
to carbon dioxide and water. Similarly, the odd hydrogen atom in the HFCs
and HCFCs makes these chemicals vulnerable to oxidation by hydroxyl radicals,
but the end products – and the way they are produced – are far more complex
and as yet little understood. Also, uncertainty about how much the concentration
of hydroxyl radicals changes with altitude makes it more difficult for scientists
to work out the rate of degradation of CFC substitutes; they suspect that
the substitutes may persist in the atmosphere for between 5 and 15 years.

The end products include carbon dioxide and hydrofluoric and hydrochloric
acids, though not in sufficient volumes to cause perceptible rain acidity.
Environmentalists are more concerned about the production of trifluoroacetic
acid (TFA). Though TFA has not yet been detected, its precursor, trifluoroacetyl
fluoride, was identified as a possible degradation product of HFC₁34a
in 1981 by Larry Anderson, an atmospheric scientist working for General
Motors, the American manufacturer. In the January 1990 issue of Environmental
Protection Bulletin, Banks proposes pathways for the atmospheric production
of TFA from both HFC₁34a and HCFC₁23, two of the leading
CFC substitutes. HFC₁34a is a replacement for CFC₁2
as a refrigerant, while HFC₁23 is a replacement for CFC₁1
for making plastic foam. Banks also shows how HRF134, an isomer of HFC₁34a
and thus a possible alternative to it, degrades without producing TFA. So
far, no research has been done on the toxicology and performance of HFC₁34
as a refrigerant (Isomers have identical molecular formulae but different
molecular structures.)

There is insufficient knowledge about the production of TFA in the atmosphere
and whether the chemical is potentially dangerous. In April 1988, the CFC
Chemical Substitutes Committee of the US Environmental Protection Agency
stressed the need for an investigation of the tropospheric chemistry of
HCFC₁23 and HFC₁34a and for a study of the toxicity
of TFA. In February this year, the Alternative Fluorocarbon Environmental
Acceptability Study (AFEAS), which brings together 15 of the chemicals industry’s
leading producers of CFCs, earmarked $6 million for a three year research
programme ‘to examine mechanisms of tropospheric degradation and the potential
effects on the environment’. Earlier this year, under its Science and Technology
for Environmental Protection (STEP) programme, the European Commission allocated
3 million ECUs (4.3 million Pounds (pds) of its 75 million ECU annual budget
for research into the ‘kinetics and mechanisms for the reactions of halogenated
organic compounds in the troposphere’. While many scientists agree that
research work is proceeding with unusual rapidity, some remain concerned
that the pace is not fast enough. In the meantime, there is a considerable
divergence of opinion.

According to McCulloch, who is also vice chairman of the AFEAS Science
Committee, TFA is not acutely toxic – high doses over a short period do
not seem to be dangerous. Referring to an AFEAS review of research over
five decades since the introduction of CFCs, Scientific Assessment of Stratospheric
Ozone, published in 1989 by the World Meteorological Organisation, he says
that a mammal must consume at least 150 milligrams of TFA per kilogram body
weight per day over five or six days before it suffers any noticeable effects.
The review also records that TFA does not cause genetic mutation; it adds,
however, that there is no long-term data to indicate whether the chemical
is a carcinogen or not. The review also notes that TFA passes rapidly through
the body without experiencing any changes – the volume remaining in the
body reduces by half every 16 hours.

But the effect of long-term exposure to smaller doses of TFA – the chemical’s
chronic toxicity – is still unknown. Banks says that research being done
in Manchester University’s Pharmacology Department indicates that plant
roots absorb TFA easily, enabling potentially dangerous levels of the chemical
to accumulate within the food chain.

TFA’s durability is uncertain. ¿ìè¶ÌÊÓƵs suspect that the chemical
may persist in the environment for many years because the bonds between
the carbon and fluorine atoms in the trifluorocarbon group of the molecule,
CF₃, are very strong, much stronger than the bonds between carbon and chlorine
atoms in CFCs. This could lead to dangerous accumulations of TFA. For the
same reason, the CF₃ group, either as a free radical or within the product
of its oxidation, may be responsible for ozone breakdown in the stratosphere,
though this has not been confirmed.

Another possibility is that TFA might eventually degrade to the highly
toxic monofluoroacetic acid (MFA). A dose of just 4 milligrams of MFA per
kilogram body weight causes convulsions in humans: it disrupts the carbohydrate
metabolism of mammals and can kill them. McCulloch dismisses the likelihood
of such a degradation path: ‘Under the conditions that would decompose chemically
stable TFA, the far less stable MFA would go very quickly.’ The official
AFEAS line is that more investigation is required. In its 1989 review, the
AFEAS noted that ‘because of the mammalian toxicity of MFA, the possibility
of defluorination of trifluoro- to monofluoro- needs to be firmly clarified’.

Banks foresees environmental problems. He bemoans the fact that little
research has been done on the effects of CFC alternatives. ‘Acid rain containing
hydrofluoric and hydrochloric acid is one thing, but when a new and organic
component like TFA is perceived to be a possibility, well-founded reassurances
are called for.’

McCulloch insists that the pace of research is fast enough. He also
criticises Banks’ approach: ‘His pathways may be possible in the laboratory
but are unlikely under highly dilute atmospheric conditions.’ ¿ìè¶ÌÊÓƵs
still do not know for certain that TFA is a degradation product of the CFC
substitutes, says McCulloch. Even if it is, he notes, the quantities released
into the atmosphere would be insignificant: ‘If we have 100 per cent conversion
to TFA, we are still only looking at parts per trillion in the atmosphere,
or parts per billion in rainwater.’ This applies to other by-products too,
he adds. If research reveals that any compound is environmentally unsuitable,
production would stop: ‘We could not carry on with fluorocarbons that were
legitimately believed to be putting dangerous pollutants into the atmosphere.’
The risk is commercial rather than environmental, he concludes.

But in a worst case scenario, just how quickly could the world’s chemical
industries turn around and come up with yet more CFC substitutes, and how
willing would they be to write off hundreds of millions of pounds invested
in brand new production facilities? In the March 1990 issue of Chemistry
in Britain, Chris Tane, ICI’s product manager involved in the development
of CFC substitutes, says: ‘It is one thing to talk about replacing them
(HCFCs) when you know what you are going to replace them with, but nobody
has the slightest idea what the hell we are going to replace them with.
It will be decades in our view before a reasonable replacement is found
– if it ever is.’

Tane’s statement reflects the disagreements that surfaced at the London
meeting in July. The new protocol on the banning of CFCs was not extended
to cover HCFCs but delegates approved a resolution that should lead to their
phasing out by 2020 if possible and by 2040 at the latest. Some industrialists
were unhappy with this move; they said it could make investment in the production
of HCFCs difficult.

Banks says there is no choice: ‘No halogenated hydrocarbons should be
released into the atmosphere until we know far more about their behaviour,’
he insists. ‘Until then, we just don’t know what we’re playing with.’

Oliver Tickell is a writer and researcher, based in Oxford, with a particular
interest in environmental issues

Recycling – a solution to the search for CFC alternatives

‘There is a limit to the amount of anything that the atmosphere can
deal with,’ says Archie McCulloch, an environmental scientist with ICI.
‘In the case of HCFCs, we believe those limits are high, but we don’t yet
know how high.’ As a result, the company is prepared to recycle its fluorocarbons.

The original manufacturers are in a good position to do this because
they can use the same equipment for recycling the chemicals as they did
for cleaning them up at the end of the production process. The aim is to
remove contaminating oils and water, for instance; in 10 years time, the
company may even be able to deal with mixed blends of fluorocarbons, which
it cannot cope with at the moment, says McCulloch.

Recycling should be given a boost by the higher cost of the new compounds,
typically about five times as much as the CFCs they replace. But it is still
uncertain whether the labour-intensive recycling process will mame recycled
chemicals more expensive than new ones.

Another major obstacle to recycling the chemicals is the European Commission’s
classification of used CFCs as Special Waste, says McCulloch. This means
that owners of the waste must take extraordinary precautions with it, which
can be expensive and time-consuming. ‘(Special Waste) classifiction makes
very good sense for toxic waste, such as PCBs, but for CFCs it is a nonsense.’
The ruling is an incentive to release used CFCs into the atmosphere, without
risking detection, rather than go to the trouble and expense of disposing
of them as the EC demands, he says. ‘You can take an old fridge across a
national boundary without restriction, but remove the CFCs for recycling
and your’re stuck.’

ICI is lobbying the commission to relax the Special Waste designation,
through industry groups and Britain’s Department of the Environment. McCulloch
is concerned that the classification could also apply to HFCs and HCFCs,
which would create problems in recycling them as well.

Environmentalists disagree. According to Fiona Weire, Air Pollution
Campaigner with Friends of the Earth, ‘the chemicals industry is confusing
two different issues – the control of hazardous chemicals and bureaucratic
streamling. We’re certainly not in favour of loads of unnecessary paperwork,
but these are dangerous chemicals which do need proper controls.’ She suggests
that the definition of Special Waste should be extended to include scrapped
equipment containing CFCs, rather than relaxed to exclude these chemicals
once they are extracted. Also, she wants industry to introduce measures
that will prevent the escape of HCFCs and HFCs at all stages during their
lifetimes, from production to recycling.

If recycling is successful worldwide, ICI estimates that global production
of HFCs and HCFCs should stay at 400,000 tonnes a year by 2050 – just over
half of what it would be otherwise. This means 400,000 tonnes of potential
pollutants still will be left in the atmosphere per year.