Environmental Chemistry:A Historical Perspective
Royal Society of Chemistry’s Environmental Chemistry Group and Historical Group at the Chemistry Centre, Burlington House
Meeting report by Leo Salter
ECG Committee Member
ECG Bulletin January 2012
Meeting report by Leo Salter
ECG Committee Member
ECG Bulletin January 2012
Environmental change and its consequences for our future energy needs have dominated much of the political debate of the first two decades of this century. This one-day symposium was an opportunity to recognise some of the scientists whose work gives us an understanding of the chemistry of the environment and underpins the concern about the impact of anthropogenic activity. Around 65 delegates attended the meeting and throughout the event their participation and questions were admirable. There were six speakers, and Professor Michael Pilling (Emeritus Professor at the University of Leeds) opened and chaired the proceedings.
The opening speaker was Professor Simon Tett from the University of Edinburgh who spoke on “Anthropogenic CO2 and climate change – a historical perspective” and whose aim was to “give a sense of the historical development of climate change studies over the last 150 years.” During the latter part of the 19th century data from Tyndall’s experiments in the 1860s led to a general consensus that water vapour, carbon dioxide and methane were such strong absorbers in the infra-red region that small changes in their concentrations would have little impact on the earth’s temperature, but this was challenged when Arrhenius (1896) showed that increases or decreases in carbon dioxide in the atmosphere would be coupled with changes in atmospheric water vapour concentrations and would produce a change in temperature. For example, if atmospheric CO2 concentrations halved then 5K cooling would occur. In the late 1930s a collation of observational data by Callendar indicated a small increase in Global Average Near-Surface Temperature and although these data were not generally accepted they did give an impetus to further work. Roger Revelle and Hans Suess made an estimate of fossil fuel carbon dioxide inputs into the atmosphere using 14C measurements of ‘old’ and ‘modern’ wood and they suggested that this ‘extra’ anthropogenic carbon dioxide was taken up by the oceans. However, Roger Revelle later threw doubt on the idea of ocean take-up by showing that ocean buffering meant that the upper ocean would then emit the CO2 back to the atmosphere. And Charles Keeling’s global measurements of carbon dioxide (which culminated in the start of the Mauna Loa record) showed increases in carbon dioxide at the South Pole and this supported the idea that anthropogenic carbon dioxide ended up in the atmosphere and not the ocean. By 1965 reports were appearing in the US which suggested that anthropogenic gases may cause climate change, and ice-core data showed that changes in greenhouse gases such as carbon dioxide paralleled ice ages.
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At this stage basic General Circulation Models began to be developed which used the principles of conservation of momentum, mass and energy, and equations of state together with exchanges across interfaces (e.g. air-sea interface) to develop the understanding of the effects of anthropogenic carbon dioxide as an emergent phenomenon – a task which has become much better refined as the computational power available increased by a factor of 16 during every decade since the 1960s. Best ’current’ estimates (2007 IPCC) for the effects of anthropogenic carbon dioxide are that carbon dioxide was responsible for half of the enhanced climate effect, that a rise of 0.3K per decade is predicted with an associated 3–to-10 cm per decade rise in sea level, and that there has been an 0.3-to-0.6 K increase in the global mean temperature over the last century.
Professor Frank James (The Royal Institution) gave a talk on the life of John Tyndall (“Held fast in the iron grip of frost’: field and laboratory in John Tyndall’s discovery of the Greenhouse Effect.”). John Tyndall (1820-1893) was born into the protestant persuasion in Ulster but later became an agnostic. He did not go to university but joined the Ordnance Survey, and after surveying in Ireland and Lancashire he took advantage of the boom in railway building in the 1840s to become a railway surveyor. Subsequently he joined Queenwood College in Hampshire to teach mathematics; the College was unusual for the period in that it taught science and was philosophical based on utopian socialism. At that time, Edward Frankland, an early proponent of organo-metallic chemistry taught chemistry there and he became a close friend of Tyndall. They both decided to go to university – first to Marburg to work with Bunsen and then to Berlin where Tyndall studied diamagnetism and the magneto-optical effect recently discovered by Faraday. In 1851 after working with Magnus at the University of Berlin Tyndall’s money ran out and he returned to Queenwood where Sabine and Jones from the Royal Institution befriended him so that in 1853 he was invited to give one of the Friday evening lectures at the RI. In a short time his lecturing became famous and he was appointed as Professor of Natural Philosophy at the RI and, although being agnostic and a social animal himself, he worked effectively with the religious and unsociable Faraday. He became friendly with Thomas Huxley and in 1856 they went to the Alps to study glaciers – as a consequence Tyndall became a noted 19th century alpinist after this visit and was first to climb the Weisshorn; he visited the Alps every summer from 1856 onwards and had a cottage at Belalp. His work on popularising science and his work on glaciers has meant that several geographical features were named after him including glaciers in Alaska, Colorado, Chile and on Mount Kenya.
Whilst looking at glaciers and climbing mountains Tyndall wondered why there were glaciers all year round when the atmosphere could be very warm in the summer and as part of his investigations around this topic in the late 1850s and early 1860s he placed various gases in a tube and discovered that gases transmitted heat by different amounts,
“Remove for a single summer-night the aqueous vapour from the air which overspreads this country, and you would assuredly destroy every plant capable of being destroyed by a freezing temperature”
Professor Frank James (The Royal Institution) gave a talk on the life of John Tyndall (“Held fast in the iron grip of frost’: field and laboratory in John Tyndall’s discovery of the Greenhouse Effect.”). John Tyndall (1820-1893) was born into the protestant persuasion in Ulster but later became an agnostic. He did not go to university but joined the Ordnance Survey, and after surveying in Ireland and Lancashire he took advantage of the boom in railway building in the 1840s to become a railway surveyor. Subsequently he joined Queenwood College in Hampshire to teach mathematics; the College was unusual for the period in that it taught science and was philosophical based on utopian socialism. At that time, Edward Frankland, an early proponent of organo-metallic chemistry taught chemistry there and he became a close friend of Tyndall. They both decided to go to university – first to Marburg to work with Bunsen and then to Berlin where Tyndall studied diamagnetism and the magneto-optical effect recently discovered by Faraday. In 1851 after working with Magnus at the University of Berlin Tyndall’s money ran out and he returned to Queenwood where Sabine and Jones from the Royal Institution befriended him so that in 1853 he was invited to give one of the Friday evening lectures at the RI. In a short time his lecturing became famous and he was appointed as Professor of Natural Philosophy at the RI and, although being agnostic and a social animal himself, he worked effectively with the religious and unsociable Faraday. He became friendly with Thomas Huxley and in 1856 they went to the Alps to study glaciers – as a consequence Tyndall became a noted 19th century alpinist after this visit and was first to climb the Weisshorn; he visited the Alps every summer from 1856 onwards and had a cottage at Belalp. His work on popularising science and his work on glaciers has meant that several geographical features were named after him including glaciers in Alaska, Colorado, Chile and on Mount Kenya.
Whilst looking at glaciers and climbing mountains Tyndall wondered why there were glaciers all year round when the atmosphere could be very warm in the summer and as part of his investigations around this topic in the late 1850s and early 1860s he placed various gases in a tube and discovered that gases transmitted heat by different amounts,
“Remove for a single summer-night the aqueous vapour from the air which overspreads this country, and you would assuredly destroy every plant capable of being destroyed by a freezing temperature”
His work showed that very small quantities of gases like H2O (and CO2) can have a large influence on the temperature of the earth. Hence, although prior to Tyndall it was widely surmised that the Earth's atmosphere had a Greenhouse Effect he showed that water vapour was a strong absorber of heat and provided the first experimental evidence in support of it. [For further information, visit the American Institute of Physics: Center for History of Physics website: Discovery of Global Warming http://www.aip.org/history/climate/bibdate.htm].
The session after lunch commenced with Professor Peter Brimblecombe (UEA) whose topic was “The life and work of Arie Jan Haagen-Smit” which focused on boundary layer air pollution in Los Angeles. Urban air in the 20th century has been characterised by a transition from the presence of primary pollutants and reducing smog to an atmosphere where secondary pollutants and photochemical smog have become dominant. Professor Brimblecombe focused on Los Angeles as an exemplar of the phenomenon of photochemical smog and the attempts to resolve the problems associated with it. He characterised LA in the early 1940s as a city of ‘vanishing streetcars’ (portrayed as a failure of the public transport system) and a deliberate decision to turn LA into a motorised city. The consequences of this were immediate and in the 1940s air pollution was so bad that baseball games were no longer visible and, during WWII, the population feared the pollution was being generated by Japanese gas attacks – though the Southern Californian Gas Company’s artificial rubber plant for butadiene was also considered as a possible source (albeit one which was protected because of its contribution to the war effort). But, even in the 1940s, there was an awareness that the LA smog was not a ‘classical’ smog but that it had a ‘peculiar nature’ - “LA has its own special brand of smog, less grim but more eye burning”. Nevertheless, in spite of recognising that there was something different about LA smog, a Bureau of Smoke Control was established in 1945 and the LA administration apologised to the population for the problem saying it “would take a few months’ to solve.
Professor Raymond Tucker (Chairman of the Engineering Department at Washington University) was invited from St Louis to help ‘solve’ the problem. His reputation was based on success in resolving pre-war issues with St Louis Smog, a problem associated with bituminous coal burning, and his comment that the automobile was definitely not the problem because there was so little sulfur in the petrol meant that little progress was made. Additionally it was also recognised that the association of the smog with a single source (i.e. the butadiene plant) which might have explained the ‘peculiar’ nature of the smog was an oversimplification.
Arie Jan Haagen-Smit (1900-1977) was a biochemist concerned with crop damage and had the skill of identifying components of the air by smell and was able to identify the presence of Criegee intermediates (products of ozonolysis) in the smog and hence say that it was caused by ‘the action of sunlight and automotive vapours’ and published his understanding of the nature of the smog in Industrial & Engineering Chemistry “The Chemistry and Physiology of LA Smog” (1952, 44, 1342) referring to the presence of both ozone and peroxides. His ideas were opposed by the automobile manufacturers who commissioned a study at Stanford. The outcome of this study was broadly supportive of Haagen-Smit’s approach though it was pointed out that more facts (reaction rates, reactive species etc.) needed to be known and, in the early 1970s, the hydroxyl radical was identified as an essential component of photochemical smog.
The story of LA Smog (and inter alia photochemical smog) is complex. The sources of the primary pollutants, their reactions, the role of the hydroxyl radical and the fact that there are multiple mobile polluters made understanding difficult and the development of policy via air quality management approaches was similarly difficult but it is remarkable that the nature of the smog only began to be unravelled when its smell was recognised by Haagen-Smit.
In the second presentation of the afternoon, “Robert Angus Smith and the search for wider and tighter pollution regulation,” Peter Reed described the early stages of the development of Alkali Works legislation and how Smith’s interpretation and application of the legislation established a modus operandi for 19th and early 20th century air pollution control in the UK.
In its initial stages (1863 legislation) the Alkali Inspectorate was chiefly directed at ensuring the capture of muriatic acid from the Leblanc process but over time (at Smith’s behest) sulfur dioxide, sulfur waste, the copper industry (emissions of ‘copper smoke’ – sulphur dioxide and hydrogen fluoride), cement works (emissions of dust, volatile salts and a smell associated with the organic matter in the clay), potteries (smoke from coal and the release of hydrogen chloride when common salt was thrown over the pottery in the final stages of glazing) and ammonia emissions (from coal gas manufacture) were also included.
Although it was sometimes difficult (as when the Inspectorate was consistently refused permission to enter the Swansea Copper plant by the family who owned it), Smith persisted with the approach that persuasion was better than enforcement because the former allowed the Inspectors to act as peripatetic advisers rather than enforcers and this (usually!) produced more success and a better working relationship with the industry. Smith was also on favour of a high degree of central rather than local control – chiefly because it meant that he could have total oversight of the quality of analyses and the mode of implementation of the regulations.
The 1863 legislation had nothing to do with health but was focused on damage to property – the Act was heavily sponsored by the landed gentry in the House of Lords because it was their land that was being damaged by the emissions. However, prior to the 1863 Alkali Works legislation the 1848 Public Health Act had set up local Boards of Health and Medical Officers of Health in those areas where the death rate was greater than 23 per 1000 – at that time these deaths were chiefly associated with cholera, typhoid and smallpox. In terms of air pollution there were arguments that copper smoke was in fact a prophylactic against contagious diseases and Henry Vivian (who owned the Swansea copper works) gave workers dilute sulphuric acid to drink during a cholera outbreak. By and large noxious vapours were not considered to be injurious to health – workers in an atmosphere of hydrogen chloride protected themselves by breathing through piece of flannel. However, in the late 1890s Whitelegge (Chief Inspector of Factories) and Legge (Medical Inspector of Factories) began to look at industrial disease and thus the two strands of the inspectorate began to develop separate but linked agendas.
By 1956 the Alkali Inspectorate was responsible for 1900 processes and 1000 works in the UK and has subsequently become ‘Her Majesty’s Inspectorate of Pollution’. As such its responsibilities in relation to national air pollution management are those associated with industrial sources as opposed to the monitoring and management of other air pollution sources (such as cars) which are the responsibility of local authorities.
The penultimate talk of the meeting (“The life and work of Frederick Challenger”) was delivered by Professor Richard Bushby (Leeds). Frederick Challenger (1887-1983) was the Professor of Organic Chemistry at the University of Leeds from 1930 to 1953 and in many ways his biography shows features which are recognisably those of scientists in the late 19th and early 20th century viz. he was born into a lower middle class family which embraced a work ethic, he studied in a provincial college and was sponsored by an academic ’patron’, he showed flair as a researcher/experimentalist and then went (like Tyndall) to Germany for doctoral studies and after being awarded a PhD he came back to the UK to develop a successful career. (And, like Haagen-Smit, he had a great interest in smells; describing compounds as having ‘butter-like’ odours and ‘the smell of a freshly opened corpse’).
Professor Raymond Tucker (Chairman of the Engineering Department at Washington University) was invited from St Louis to help ‘solve’ the problem. His reputation was based on success in resolving pre-war issues with St Louis Smog, a problem associated with bituminous coal burning, and his comment that the automobile was definitely not the problem because there was so little sulfur in the petrol meant that little progress was made. Additionally it was also recognised that the association of the smog with a single source (i.e. the butadiene plant) which might have explained the ‘peculiar’ nature of the smog was an oversimplification.
Arie Jan Haagen-Smit (1900-1977) was a biochemist concerned with crop damage and had the skill of identifying components of the air by smell and was able to identify the presence of Criegee intermediates (products of ozonolysis) in the smog and hence say that it was caused by ‘the action of sunlight and automotive vapours’ and published his understanding of the nature of the smog in Industrial & Engineering Chemistry “The Chemistry and Physiology of LA Smog” (1952, 44, 1342) referring to the presence of both ozone and peroxides. His ideas were opposed by the automobile manufacturers who commissioned a study at Stanford. The outcome of this study was broadly supportive of Haagen-Smit’s approach though it was pointed out that more facts (reaction rates, reactive species etc.) needed to be known and, in the early 1970s, the hydroxyl radical was identified as an essential component of photochemical smog.
The story of LA Smog (and inter alia photochemical smog) is complex. The sources of the primary pollutants, their reactions, the role of the hydroxyl radical and the fact that there are multiple mobile polluters made understanding difficult and the development of policy via air quality management approaches was similarly difficult but it is remarkable that the nature of the smog only began to be unravelled when its smell was recognised by Haagen-Smit.
In the second presentation of the afternoon, “Robert Angus Smith and the search for wider and tighter pollution regulation,” Peter Reed described the early stages of the development of Alkali Works legislation and how Smith’s interpretation and application of the legislation established a modus operandi for 19th and early 20th century air pollution control in the UK.
In its initial stages (1863 legislation) the Alkali Inspectorate was chiefly directed at ensuring the capture of muriatic acid from the Leblanc process but over time (at Smith’s behest) sulfur dioxide, sulfur waste, the copper industry (emissions of ‘copper smoke’ – sulphur dioxide and hydrogen fluoride), cement works (emissions of dust, volatile salts and a smell associated with the organic matter in the clay), potteries (smoke from coal and the release of hydrogen chloride when common salt was thrown over the pottery in the final stages of glazing) and ammonia emissions (from coal gas manufacture) were also included.
Although it was sometimes difficult (as when the Inspectorate was consistently refused permission to enter the Swansea Copper plant by the family who owned it), Smith persisted with the approach that persuasion was better than enforcement because the former allowed the Inspectors to act as peripatetic advisers rather than enforcers and this (usually!) produced more success and a better working relationship with the industry. Smith was also on favour of a high degree of central rather than local control – chiefly because it meant that he could have total oversight of the quality of analyses and the mode of implementation of the regulations.
The 1863 legislation had nothing to do with health but was focused on damage to property – the Act was heavily sponsored by the landed gentry in the House of Lords because it was their land that was being damaged by the emissions. However, prior to the 1863 Alkali Works legislation the 1848 Public Health Act had set up local Boards of Health and Medical Officers of Health in those areas where the death rate was greater than 23 per 1000 – at that time these deaths were chiefly associated with cholera, typhoid and smallpox. In terms of air pollution there were arguments that copper smoke was in fact a prophylactic against contagious diseases and Henry Vivian (who owned the Swansea copper works) gave workers dilute sulphuric acid to drink during a cholera outbreak. By and large noxious vapours were not considered to be injurious to health – workers in an atmosphere of hydrogen chloride protected themselves by breathing through piece of flannel. However, in the late 1890s Whitelegge (Chief Inspector of Factories) and Legge (Medical Inspector of Factories) began to look at industrial disease and thus the two strands of the inspectorate began to develop separate but linked agendas.
By 1956 the Alkali Inspectorate was responsible for 1900 processes and 1000 works in the UK and has subsequently become ‘Her Majesty’s Inspectorate of Pollution’. As such its responsibilities in relation to national air pollution management are those associated with industrial sources as opposed to the monitoring and management of other air pollution sources (such as cars) which are the responsibility of local authorities.
The penultimate talk of the meeting (“The life and work of Frederick Challenger”) was delivered by Professor Richard Bushby (Leeds). Frederick Challenger (1887-1983) was the Professor of Organic Chemistry at the University of Leeds from 1930 to 1953 and in many ways his biography shows features which are recognisably those of scientists in the late 19th and early 20th century viz. he was born into a lower middle class family which embraced a work ethic, he studied in a provincial college and was sponsored by an academic ’patron’, he showed flair as a researcher/experimentalist and then went (like Tyndall) to Germany for doctoral studies and after being awarded a PhD he came back to the UK to develop a successful career. (And, like Haagen-Smit, he had a great interest in smells; describing compounds as having ‘butter-like’ odours and ‘the smell of a freshly opened corpse’).
Challenger was born in the north of England (Halifax) and his father was a Methodist minister, he studied at Derby Technical College and in 1907 was awarded a London University External BSc in Chemistry. The Head of Chemistry at Derby (Jamieson Walker) encouraged him to apply for a job as a research assistant at Nottingham and whilst there Challenger published papers on organosilicon and organophosphorus and synthesised an optically active compound based on an asymmetric tetrahedral silicon atom. This work contributed to the award of an 1851 Exhibition Scholarship and he used this to go to Göttingen to work with the Nobel Laureate Otto Wallach on the terpenes thujone and thujaketonic acid – he also attended lectures on microbiological chemistry in Koch’s laboratories. On his return to England in 1912 Challenger first worked as an assistant lecturer and demonstrator at Birmingham. There he became Acting Head in 1919 and was awarded his DSc in 1920. He moved to Manchester as a Senior Lecturer in 1920 and worked there until 1930 (in the same department as Robert Robinson). In 1930 Robinson’s support for Challenger was sufficient for him to be appointed Head at Leeds in spite of the internal competition (J. W. Baker) sponsored by Christopher Ingold. His links to what is now known as Environmental Chemistry began in 1931 when he was asked to investigate the deaths of two children in the Forest of Dean which were attributed to Gosio Gas – the volatile form of arsenic formed by the action of fungi on arsenical green pigments used in wall paper and in clothing. Whatever the correctness of the identification of Gosio Gas as the killing agent, what is known is that Challenger successfully identified Gosio Gas as Me3As rather than Et2AsH which it was previously thought to be (J. Chem. Soc., 1933, 95-101). Challenger extended this work to look at the function of the moulds Scopulariopsis brevicaulis and Penicillium notatum in the production of Me2Se, Me2Te and Me3Sb by the unusual methylating agent which they contained (now known to be S-adenosylmethionine). This work on biological methylation is Challenger’s major contribution to the field of environmental chemistry and has great ongoing importance for understanding the ways in which metals and metalloids are made bioavailable.
The final talk was given by Chris Cooksey on “The emergence of health concerns of the heavy metals and metalloids”. This presentation focused on the development of LD50 as a measure of toxicity (J. W. Trevan, “The error of determination of toxicity” Proc. Roy. Soc., 1927, 101B, 483) and its subsequent translation into simple scales. [(Hodge and Sterner Scale – a 6-point scale ranging from extremely toxic (LD50 ≤ 1) to relatively harmless (LD50 >15000); the 4-point Globally Harmonized System of Classification and Labelling of Chemicals (LD50 ≤ 5 ‘Danger’ to LD50 300-2000 ‘Warning’)]. Arsenic, mercury, lead and cadmium were then used as case studies to illustrate how awareness and knowledge of their effects developed over the later 19th and 20th centuries.
Arsenic’s main use in the 19th century was as a pesticide (“Rough on Rats”) – it was also known as ‘inheritance powder’! More recently, during the Vietnam War arsenic containing compounds (sodium cacodylate and cacodylic acid – Agent Blue) were used as a ‘rainbow herbicide’ on rice paddies and other crops to deprive the Viet Cong of food crops. Arsenic poisoning kills by allosteric inhibition of essential metabolic enzymes, leading to death from multi-system organ failure – the more methylated the arsenic compound the less toxic it is (e.g. LD50 arsenate 112-175; LD50 dimethylarsinic acid 650). Trimethylarsine (Gosio Gas) has low toxicity chiefly because the process of inhalation limits its ingestion (The toxicity of trimethylarsine: an urban myth, J. Environ. Monit., 2005, 7, 11-15).
Mercury has been widely used (e.g. in Castner-Kellner Cells, for gold extraction, dental fillings, and measuring instruments). Peaks in the historical signature of mercury in the Fremont Glacier occur when volcanoes erupt (Tambora 1815, Krakatoa 1883, Mt St Helens 1980) and (because of its use to extract gold) during the periods of gold exploration (e.g. the 1850-1875 gold rush). Sixty-five percent of environmental mercury is from coal-fired power plants. Mercury has a long history of toxicity, and alkylation of mercury compounds in the environment (as occurred in Minamata) makes them more toxic. Currently dental fillings are the highest source of mercury exposure in Europe, and a fifty percent reduction in mercury emissions from crematoria by 2012 is demanded by EU legislation.
Lead poisoning causes ‘colic’, and beer standing overnight in lead pipes has been known to cause death (A Case of Lead Poisoning by Beer” E. R. Morgan, British Medical Journal, 1900, 1373). Lead, in its most recently ubiquitous tetraethyl form, has caused significant environmental damage which, since in the 1920s ten people died of insanity whilst working at the Ethyl Gasoline Company (which brought it to market), should have been signposted long before it was.
Cadmium was isolated in 1817 and the first report of poisoning was related to the cleaning of silver with cadmium carbonate in 1858. The most famous case of chronic poisoning occurred from around 1912 in the Toyama Prefecture of Japan due to cadmium extraction by the Mitsui Mining and Smelting Co and the consequent contamination of the Jinzu River. Since the river was used mainly for the irrigation rice fields cadmium accumulated in the people eating contaminated rice. Cadmium poisoning causes softening of the bones and kidney failure and the symptoms of intense pain from bone fractures and damage to joints and the spine gives its name (itai-itai – ‘ouch ouch’). Production increased even more before WWII. The mines are still in operation and cadmium pollution levels remain high, although improved nutrition and medical care has reduced the occurrence of itai-itai.
The meeting was wide-ranging in its topics and gave a picture of some of the personalities and events responsible for the early stages in the development of environmental chemistry as a field of specialised study. It is noteworthy that knowledge and understanding of issues were gained from the personal enthusiasms and curiosity of highly skilled and highly motivated individuals; for the most part these were natural scientists, chemists, meteorologists and officers from local government and national agencies. Very few of them seemed to be driven by the exigencies of profit.
LEO SALTER
Chairman, RSC Environmental Chemistry Group
(Articles based on the proceedings of this meeting may be found on pp 9-28
Arsenic’s main use in the 19th century was as a pesticide (“Rough on Rats”) – it was also known as ‘inheritance powder’! More recently, during the Vietnam War arsenic containing compounds (sodium cacodylate and cacodylic acid – Agent Blue) were used as a ‘rainbow herbicide’ on rice paddies and other crops to deprive the Viet Cong of food crops. Arsenic poisoning kills by allosteric inhibition of essential metabolic enzymes, leading to death from multi-system organ failure – the more methylated the arsenic compound the less toxic it is (e.g. LD50 arsenate 112-175; LD50 dimethylarsinic acid 650). Trimethylarsine (Gosio Gas) has low toxicity chiefly because the process of inhalation limits its ingestion (The toxicity of trimethylarsine: an urban myth, J. Environ. Monit., 2005, 7, 11-15).
Mercury has been widely used (e.g. in Castner-Kellner Cells, for gold extraction, dental fillings, and measuring instruments). Peaks in the historical signature of mercury in the Fremont Glacier occur when volcanoes erupt (Tambora 1815, Krakatoa 1883, Mt St Helens 1980) and (because of its use to extract gold) during the periods of gold exploration (e.g. the 1850-1875 gold rush). Sixty-five percent of environmental mercury is from coal-fired power plants. Mercury has a long history of toxicity, and alkylation of mercury compounds in the environment (as occurred in Minamata) makes them more toxic. Currently dental fillings are the highest source of mercury exposure in Europe, and a fifty percent reduction in mercury emissions from crematoria by 2012 is demanded by EU legislation.
Lead poisoning causes ‘colic’, and beer standing overnight in lead pipes has been known to cause death (A Case of Lead Poisoning by Beer” E. R. Morgan, British Medical Journal, 1900, 1373). Lead, in its most recently ubiquitous tetraethyl form, has caused significant environmental damage which, since in the 1920s ten people died of insanity whilst working at the Ethyl Gasoline Company (which brought it to market), should have been signposted long before it was.
Cadmium was isolated in 1817 and the first report of poisoning was related to the cleaning of silver with cadmium carbonate in 1858. The most famous case of chronic poisoning occurred from around 1912 in the Toyama Prefecture of Japan due to cadmium extraction by the Mitsui Mining and Smelting Co and the consequent contamination of the Jinzu River. Since the river was used mainly for the irrigation rice fields cadmium accumulated in the people eating contaminated rice. Cadmium poisoning causes softening of the bones and kidney failure and the symptoms of intense pain from bone fractures and damage to joints and the spine gives its name (itai-itai – ‘ouch ouch’). Production increased even more before WWII. The mines are still in operation and cadmium pollution levels remain high, although improved nutrition and medical care has reduced the occurrence of itai-itai.
The meeting was wide-ranging in its topics and gave a picture of some of the personalities and events responsible for the early stages in the development of environmental chemistry as a field of specialised study. It is noteworthy that knowledge and understanding of issues were gained from the personal enthusiasms and curiosity of highly skilled and highly motivated individuals; for the most part these were natural scientists, chemists, meteorologists and officers from local government and national agencies. Very few of them seemed to be driven by the exigencies of profit.
LEO SALTER
Chairman, RSC Environmental Chemistry Group
(Articles based on the proceedings of this meeting may be found on pp 9-28