Tunnel vision

I went to look at a specialist manufacturing facility this week where they produce and handle small amounts if a highly potent compound. I've been asked to carry out a COSHH assessment for the process. As they weren't manufacturing I was given a "guided tour" of the process and was able to take a good look around at the facility itself and the control measures in place. My discussions with the production personnel concentrated on the control of the potent substance itself. Other substances used during manufacture were mentioned, but only in passing. Some of these presented health hazards (although they were clearly not as harmful as the potent substances), but the personnel were so focused on the potent that they didn't really make any comments on the hazards and risks from these other substances and the measures used to control them.

It's very easy to get "tunnel vision" with processes like this where a potent substance is being handled. What I mean by this is that so much attention is devoted to the main hazard that possible risks from other substances or agents can be forgotten. This can lead to problems if some of those risks are significant and aren't controlled. Although its clearly very important to ensure that everyone is aware of the risks from the main potent material, and that a very high standard of control is applied, attention also needs to be paid to other hazards to make sure that any risks they present are properly controlled as well.

Sir Humphry and the Age of Wonder

I think its important that people working in a particular field of expertise should be more than one dimensional and cultivate interests in other areas. I've always had a passion for history, literature and reading in general. A long time favourite book is Richard Holmes' "Footsteps", a book which combines biography, travel and autobiography. His biography of Shelley is also a favourite. So when I heard that a new book of his was due out that focused on the development of science in the "romantic age" I bought a copy hot off the press - even though it was in hardback, as I didn't want to wait the extra months it would take for a paperback edition to be published (mind you a half price offer made it even more tempting!).

As in Footsteps, Holmes covers the life of more than one subject and also wanders off down sidetracks related to the main theme. One of the main topics is the life of Sir Humphrey Davy. I've always had an interest in this pioneering chemist so was keen to read this section of the book. He is best known for his invention of the safety lamp and he is also credited with the discovery (or isolation) of sodium, potassium and barium. But there is a lot more to his life.



Humphrey Davy came from humble beginnings in Cornwall, being born in Penzance in 1778. In 1794 he was apprenticed to John Bingham Borlase, a Penzance surgeon, but in 1798 was taken on to Thomas Bedooes to work as a laboratory assistant in the latter's newly established Pneumatic Institution in Bristol. It was here that Davy was able to develop his talents as an experimental scientist, before finally moving to London in 1801 to work at the Royal Institution.

There's a tendency these days to separate arts and science - but Davy moved in both worlds, as did many other prominent artists and scientists at the time. He was a friend of Wordsworth and Coleridge who took an interest in his work, as did others, including Shelley and Keats - Davy even wrote poetry himself. Men of ideas were interested in more than one sphere of knowledge and culture.

As an occupational hygienist it was particularly interesting to read about Davy's experiments with gases in Bristol. He explored the effects of nitrous oxide and carbon monoxide by conducting inhalation studies on himself. On more than one occasion he came close to death by exposing himself to high concentrations of carbon monoxide.

One of the things I admire about Davy was his invention of the miner's safety lamp. Although this is surrounded by controversy (not least disputes about who first developed the lamp with George Stevenson) Davy was largely motivated by a desire to save lives (although the search for glory was a factor too, it has to be said) and he refused to take out a patent, even though strongly encouraged to do so. He wanted his lamp to be freely available. Sadly, although the lamp was intended to save lives it has been said that it actually caused the death of more men because the mine owners used the lamp as an excuse to send their workers into more dangerous workings. However, the ones really responsible for this were the greedy mine owners. Davy cannot be blamed for the misuse of his invention by others.



Although he had radical tendencies in his youth, he moved to the right in older age as he became part of the establishment (sadly this is too often the case). He also had a tendency to seek glory and credit for inventions and could be jealous of others who worked with him - notably Michael Faraday who started out as Davy's assistant. Nevertheless there is much about him to admire and Holmes, who is clearly sympathetic towards his subject, has written an educative and entertaining account of his life. And although the book as a whole is excellent, it was worth shelling out for a hardback book for this alone.

Shipping can be bad for health

I guess we usually think of shipping as more "environmentally friendly" form of transport compared to aircraft and motor vehicles. However, there was an interesting article in the Guardian today about the health risks of emissions from shipping.

Ships burn fuel oil - one of the "dirtier" fuels, containing high levels of sulphur. So emissions of sulphur dioxide are significant. The heat of the combustion process also generates another toxic gas - nitrogen dioxide. Both of these acid gases have harmful effects on human health and can also damage other living organisms. Particulate pollutants are also emitted.

Key points in the article include

• "just 15 of the world's biggest ships may now emit as much pollution as all the world's 760m cars"
• "pollution from the world's 90,000 cargo ships leads to 60,000 deaths a year in the US alone and costs up to $330bn per year in health costs from lung and heart diseases."
• 1,000 Danish people die prematurely each year because of shipping pollution and shipping emissions cost the Danish health service almost £5bn a year, mainly treating cancers and heart problems.

Dealing with these health related problems will not be easy. Control over shipping is notoriously difficult as a ship isn't based in one country. Concerted international action will be needed which can be easily circumvented by countries which allow ships to register under a "flag of convenience"

The economics of childhood lead poisoning

Following on from my post on lead yesterday, I stumbled on the following article

Childhood Lead Poisoning: Conservative Estimates of the Social and Economic Benefits of Lead Hazard Control

Published on the Environmental Health Perspectives website.

The study involved undertaking a cost-benefit analysis which quantified the social and economic
benefits to households of lead paint hazard control balanced against the investments needed to minimize exposure to these hazards. The conclusions of the study are

"there are substantial returns to investing in lead hazard control, particularly targeted at early intervention in communities most likely at risk. Given the high societal costs of inaction, lead hazard control appears to be well worth the price."

The analysis is really only relevant to the USA as the economic factors, which include the costs of health care, costs of education, earnings, and taxes are only applicable there. Nevertheless I'm sure that a similar analysis undertaken in other developed countries would reach similar conclusions. Hopefully the findings are convincing enough to influence regulators. However, in the developing world different conclusions would probably be reached if the need to control lead was considered only from an economic perspective. Is the health of children there any less important even if the balance in the cost-benefit equation is different?

Health is not just an economic issue. Although economic arguments can help to persuade governments of a need to take action, the right to good health goes beyond that. Ethical considerations must surely carry more weight.

Hypothermia

Working outdoors in Alaska

A recent posting on the Catlin Arctic survey blog discusses the effects of working in temperatures of below -40 degrees centigrade.

Hypothermia is the result of general cooling of the body below 35 degrees C. Early symptoms include tiredness, muscular weakness and confusion. Below 30 to 32 degrees shivering stops and unconsciousness can occur. When shivering stops there is a rapid decrease of body temperature. Death may occur at where the core temperature is around or below 28 degrees C.

The body produces heat and the harder you are working the more heat is generated. At low temperatures we are likely to lose heat to the environment, the extent of this heat loss, however, will be influenced by the amount and type of clothing being worn. Chemical protective clothing can present a particular problem. Even in cold environments it is possible to suffer heat stress and strain where heavy work is being undertaken and impervious clothing is worn which does not allow enough of the heat produced to escape. This is particularly relevant to chemical workers and emergency response personnel.

The Catlin team are pulling heavy sledges of 110 kilos each an average of 6 nautical miles a day. Their clothing is of a high standard in terms of the insulation it provides, but insulation alone is not enough to prevent hypothermia in such extreme conditions as they are experiencing. as the team Doctor notes

“All clothing can do is slow down the process of losing heat. “The only way they can keep the hypothermia at bay is to keep moving and to keep eating”.

Handel exhibition suggests his poison was the lead in his wine

I spotted an interesting article in the Guardian last week, reporting on a theory that the composer Handel suffered from lead poisoning


Lead acetate used to be used to sweeten wine and this is suggested as the source of lead exposure for the composer. I've even heard it suggested that the fall of the Roman empire could be attributed to the same reason as they, apparently, were very fond of sweet wine and used to add lead acetate to it. There is a useful summary of the history of lead exposure here on the USEPA website

Lead and its compounds are highly toxic. The main concerns are its chronic effects (due to long term exposure) particularly as it is accumulates in the body, remaining there for a long time after exposure.

Its principle effects include

• anaemia,
  
• irritability, tiredness,
  
• effects on the nervous system leading to muscle weakness and, in extreme case, paralysis,
• kidney and liver damage
• gastrointestinal disturbances
• effects on IQ, particularly in children
• It is a teratogen, that is it can affect the unborn child when the mother is exposed, leading to spontaneous abortion, still birth or decreased birth weight,
  
• fertility problems in males
  

Inorganic lead compounds are are also classified as "probably carcinogenic to humans" by
the International Agency for Research on Cancer (IARC)

For a thorough summary of its effects see the document Information on lead from the UK Health Protection Agency

Exposure to lead in the developed world has fallen dramatically due to increased awareness, stringent legislation in the workplace (such as the Control of Lead at Work Regulations in the UK), environmental regulation and the reduction of lead in products to which the general public could be exposed. The banning of lead in petrol being a particularly important measure. Consequently cases of lead poisoning are relatively rare.

However, it is likely that lead exposure is increasing in the developing world as lead and its compounds are still widely used in manufacturing and with the rapid growth of industry in India, China and other countries it is likely that the exposure of workers and the general public will increase. Control measures to reduce the exposure of workers and minimise emissions to the environmental are likely to be considerably less stringent in newly developing countries than in the developed world. A report by the World Health Organisation discusses these issues and concludes that:

"Public health measures should continue to be directed to the reduction and prevention of exposure to lead by reducing the use of the metal and its compounds and by minimizing lead-containing emissions that result in human exposures."