The skin we live in Part II (The Re-exposure)

The skin we live in Part II (The Re-exposure)

In my last blog I depressed myself (and possibly you, as well) with tales of industrial poisoning on a small and large scale. And I confessed to the strange habit of putting an organic solvent on my skin just to see what it would do (taste funny, among other things. Those of you who have met me now have yet another reason to explain why I am the way I am).

Now, you might think that the release of a dangerous substance with toxic properties into the workplace and wider environment is a rarity. The episodes that I have recounted are one-offs that do not normally occur. They are a lazy Hollywood script-writer’s tool for creating narrative tension, not a reality of our modern, civilised age, surely? Especially in a western democratic society, where those in charge are directly accountable to those who they care for. . .

If you want a really nice example (and who wouldn’t?) of alleged corporate greed and avarice, then look no further than the story of lead in petrol.
The use of organic lead (tetraethyl lead) in petrol dates back to the 1920s. Before that date, petrol engines suffered from a condition called ‘knocking’, which was caused by the premature ignition and explosion of the petrol/air mix in the cylinder as a result of compression. The cure for this engine-degrading phenomenon was discovered by Thomas Midgely, working for General Motors, in 1921. The efficacy of lead as a petrol additive was so great that GM and Esso/Exxon joined forces to form a company with the express intent of producing and marketing the additive. It does not appear to have occurred to the manufacturers that the addition of a known cumulative toxin in petrol might lead to increased uptake by those unfortunate enough to be anywhere in the vicinity of the exhaust gases of a petrol engine.

In fact, I am being unkind – the companies knew exactly what they were doing. They called themselves the Ethyl Gasoline Corporation to avoid any negative associations with lead, and various individuals and organisations raised concerns about the use of organic lead as early as 1922, to no avail. Midgely even inhaled tetraethyl lead vapour at a press conference to demonstrate its harmlessness (and suffered lead poisoning several months afterwards).

The corporation retained the services of a chief medical consultant, who was able to persuade the authorities for decades about the safety of the lead additive. When persuasion failed they turned to litigation and dirty tricks; suing the US Environmental Protection Agency when it attempted to regulate, and smearing the professional reputation of any researcher who might attempt to make a link between organic lead exposure and ill-health. Eventually, the evidence became irrefutable and the phase-out of leaded petrol began in the US in 1973. It has now gone almost global. Despite this the Independent newspaper ran an exposé on a UK company that was manufacturing and exporting tetraethyl lead to unstable developing countries where the ban has not been implemented.

The main target for lead poisoning is the nervous system, though other organs and systems are also affected. Long-term exposure in adults causes degradation of the central nervous system, palsy and anaemia. Exposure to high levels can severely damage the brain and kidneys in adults or children, and ultimately cause death. In pregnant women, high levels of exposure to lead may cause miscarriage.

Surprisingly, lead poisoning is not a 20th-century phenomenon. The Romans made extensive use of lead, notably for water pipes. The chemical symbol for lead, Pb, is derived from its Latin name Plumbum (no, I am not making this up and Miranda had no part in this blog), from which we get plumbing and plumber. Lead is even implicated in the fall of the Roman Empire; they used lead acetate as a sweetener for wine (which might explain the dementia of Caligula and other Roman emperors).

Well, DMSO wasn’t available in Roman times.

There is one final note of interest in this story. Thomas Midgely, the inventor of tetraethyl lead, later turned his attention to the problem of refrigerant gases. Refrigerant gases at the time were often toxic and/ or flammable. For example, ammonia, which is very soluble in water, dissolves in the water on your mucous membranes to form an irritant/corrosive
solution and is toxic at low concentrations, causing death by pulmonary oedema. You literately drown in your own lung-tissue fluid. Ammonia is also explosive at low concentrations in air. So, filling refrigeration plant with ammonia gas is not without its risks. Midgely overcame this problem by creating a compound with more appropriate properties, dichlorodifluoromethane – Freon-12, the world’s first CFCs. Yes, that’s right – the same group of compounds that were later discovered to have a significant effect on ozone (O3).

It has been said of Midgely that “he had more impact on the atmosphere than any other single organism in Earth’s history”. And I suspect if we added the word ‘negative’ in front of ‘impact’ it would still ring true.

Now, ozone itself is a hazardous substance – a respiratory irritant that has been assigned a WEL in EH40. So, the fact that CFCs have a deleterious effect on ozone concentrations might not be seen as a problem if that ozone is hanging around at ground level. But it is a problem if those CFCs destroy the thin layer of ozone that sits high up in the stratosphere (10-50km up), since that ozone has no harmful effects on human health. In fact, quite the opposite: it acts as a filter to harmful ultraviolet rays that would otherwise reach the surface of the planet, leading to increased UV exposure and the various acute and chronic health effects that ensue.

Most of us know what happens if you are over-exposed to UV radiation: the skin is burned (erythema) and the surface of the eye becomes reddened, inflamed and painful (photokeratitis). The first condition will have been experienced by most of us at some time or another if we have not been careful enough with the factor 30 – sunburn. The second condition is well known to welders (who call it arc-eye) and mountaineers (who call it snow blindness).

If you want an interesting story about snow blindness, then please read the book Annapurna by Maurice Herzog. He was the leader of a French expedition to climb the Himalayan peak Annapurna I in 1950 and thus be the first person ever to set foot on top of a mountain more than 8,000 metres high. The first half of the book is an unexceptional explanation about how the expedition first had to locate Annapurna I (it is hidden in the midst of a large range of surrounding peaks) before climbing it. The second half of the book is a hair-raising account of how the mountaineers became snow-blinded and frost-bitten on their descent of the peak and of how all of Herzog’s fingers and toes were amputated, piece by piece, by the expedition doctor as frost bite and subsequent gangrene took hold. It makes for excruciating reading. He returned to France a national hero, became the mayor of Chamonix and never climbed again.

More alarming than the acute health effects of exposure to UV are the chronic health effects – an increased risk of skin cancer (e.g. melanoma). As with all carcinogens there is no known safe level of exposure to UV radiation. The risk of cancer increases as the exposure increases. The greater the exposure, the greater the risk. However, it does seem to be the case that if the skin becomes damaged through UV exposure it significantly increases the risk. So getting sunburnt significantly increases the risk of skin cancer and the more frequently this occurs, the greater the cancer risk. Melanoma is a particularly nasty form of skin cancer because if not detected early, the tumour cells can metastasise (become capable of spreading to proliferate in other parts of the body). Ill-health symptoms will only appear after this metastasis has taken place, so early detection of the tumour (which will appear as a changing, growing mole) is important.

But I digress. Back to my main thread. Thomas Midgely, who managed in one lifetime to invent both tetraethyl lead and CFCs, is unusual in one final respect. Crippled by polio he was confined to his bed in his later years. Always the inventor he devised a system of ropes and pulleys so that he could be hoisted in and out of bed more easily. He was discovered dead, entangled in his own contraption in 1944 at the age of 55.

I don’t think the Dead Kennedys sang a song about that. And the world is a poorer place as a consequence.

Jim Phelpstead

Jim Phelpstead BSc, PhD, CMIOSH

Working in health and safety for 18 years Jim is a long-standing RRC Associate Tutor, who loves the great outdoors.