Letters August 2013

Chemophobia or common sense?

In his article ‘Fear and loathing’, Mark Peplow mentions fearing your sofa. But it was only a few years ago that the public had good reason to fear the sofa when they were exposed to anti-mould chemicals used to treat the leather, leaving thousands of people with serious skin complaints.
The report by the Royal College of Obstetricians and Gynaecologists was not chemophobic but said that there is not enough information for expectant mothers (or the general public) to assess risks from chemical exposure for many common products. The authors write: ‘On present evidence, it is impossible to assess the risk, if any, of such exposures. Obtaining more definitive guidance is likely to take many years; there is considerable uncertainty about the risks of chemical exposure.’ There is nothing chemophobic in this statement. Even I, a chemist, struggle to understand the list of ingredients on many cosmetic products. I am allergic to some chemicals and keep a look out for them but imagine the dilemma faced by pregnant women without such knowledge. The main gist of the report is to list items that should be treated with caution so as to reduce the risk to the woman and the foetus. What is wrong with that? It is certainly not chemophobic.
In the end we have to rely on the industry to protect customers but the chemical industry does itself no favours by defending themselves with the usual ‘there is no proven link between x and y’ when the chemical exposure problem is identified.
M Marriott CChem FRSC
Warrington, UK

Mining concern

I worry that the environmental and financial cost of building and launching a space rocket will stop space mining being done. Working in industrial materials recycling I tend to think about more down to earth sources of metals.
I would like to point out that landfill mining and recycling waste offer easier methods of obtaining metals. The key struggle in recycling is to find a method of separating a high purity product from a complex mixture. Also, for recycling the contents of a landfill, the right legal framework needs to exist. During landfill mining a mixture of the ‘ore’ and useless matter will have to be dug out of the landfill, sorted and the useless matter returned to the landfill. If landfill tax is charged for returning waste to a landfill then this activity will be wrongly discouraged. I hold the view that no landfill tax should apply when waste is returned to a landfill after having been dug up during landfill mining.
M Foreman
Chalmers University of Technology, Sweden

Calculating limits

William Penney, later to be elevated to Lord Penney for directing the construction of the British atomic bomb, had a productive spell of research in quantum chemistry in the 1930s, and wrote a little known book, The quantum theory of valence. In this he says: ‘If it were possible to work out in practice, instead of in principle, the interactions and energy of any system of atoms, the need for introducing the concept of valence would never arise.’
Penney, trained as a mathematician and physicist, is following the famous opinion of Paul Dirac that the mathematical equations underlining chemistry are known, but the equations are (in 1929) too complex to be solved. As a chemist, I am far from adopting Penney’s view, but my reading of Philip Ball’s article on the controversy surrounding the interpretation of recent calculations on the molecule C2 suggests that those doing computational chemistry might sometimes be pushing the analysis of their results too far.
Let us leave aside the fact that valence is an important part of the language of chemistry and essential for drawing molecular structures. The concept arose in order to rationalise the composition and structure of molecules known in the 19th century, and it has some limitations for chemistry developed since that time. There are very few cases in which it would give a better understanding of the structures of electronic excited states, and there are many examples where the concept is not useful for unstable molecules.
Computational chemistry is at its most valuable when examining unstable or even unknown chemical species, but to interpret the outcome in traditional chemical language may not always lead to a greater understanding of the results, or to the development of models that allow predictions of structure and stability to be made on related species. In short, the concepts of valence and counting bonds may not be profitable for many unstable species.
J Murrell CChem FRSC FRS
University of Sussex, UK

Photochemical fiction

David Jones ends his interesting article  with a comment and question about ‘a lovely old story’ in which the ‘goodie’ (a chemist) eliminates the ‘baddie’ by using the photochemical reaction between hydrogen and chlorine.  
I assume that Jones is thinking of A race with the sun by L T Meade and C Halifax from 1897.  Photochemistry does play a crucial part in the story, but not through a hero-chemist turned aerodynamic executioner.  Interested readers are invited to visit the nasa webpage for links to the original story in The Strand magazine and to learn the identities of Meade and Halifax, both pseudonyms.
R Hudson FRSC
NASA Goddard Space Flight Center, US

A call to toxicology

As a PhD organic chemist who subsequently trained in toxicology, I believe that I’ve benefitted greatly from being able to integrate the two disciplines. However, relatively few toxicologists have a background in chemistry, in spite of the fact that knowledge of the chemical properties of test materials is a critical part of the overall safety assessment. Toxicology is too important to be left to non-chemists, and so, like Helen Carmichael, I would encourage chemists to strongly consider obtaining an MSc, particularly in toxicology. 
D Snodin  FRSC
Bristol, UK 

Meeting reminder

Recent references to Alexander Todd took me back to the late 1970s when he visited Australia as a non-executive director of Fisons Pharmaceuticals. I was the quality control manager for Fisons Australia and had the honour and privilege of escorting Todd around the manufacturing premises and then driving him to the company’s head office in Sydney.  
Todd had the great attribute of putting everyone at ease, making time to speak with as many people as possible, expressing a keen interest in individual projects and in so doing, completely dispelling any feelings of apprehension young chemists may have had.
Like me, I am sure that those erstwhile colleagues will remember with pleasure the brief meeting with such an eminent scientist with a very human touch. 
A Wright CChem MRSC
Baulkham Hills, Australia

Expo absence

We are reminded that ChemSpec Europe was established in the UK in 1986 (Chemistry World, June 2013, supplement). But, when was the last time ChemSpec was held in the UK? In view of the great contributions that the chemical and pharmaceutical industries make to the UK economy, and given our ability to host key international events such as the Olympics, when can we expect to see ChemSpec and other major expos like CPhI Worldwide return to the UK?
H Zavareh CChem FRSC
Cambridge, UK

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