Cot death and antimony

From the 1950s onwards most babies slept on foam mattresses with waterproof polyvinyl chloride (PVC) covers. In 1988 it became a legal requirement to use additives to reduce the risk of fire from household furniture, and this meant that mattresses had to contain fire-retardants. In most cases this meant adding antimony oxide to the PVC covers. From the 1950s onwards, the incidence of cot death started to increase, and by the late 1980s about 23 babies in every 10000 were dying for no apparent reason and from no detectable cause. Was there a connection between the introduction of PVC mattresses and the appearance of cot death? Two Englishmen thought there was, and put forward an hypothesis as to why this might be so: stibine gas was being emitted by the mattresses and poisoning the babies. They publicized their theory on radio and in a letter to a leading medical magazine -and so began a campaign by pressure groups that was to last almost seven years, and which at various times had thousands of young parents discarding cot mattresses and phoning helplines in near panic.

The phrase 'cot death' - which has the emotive power of an oxymoron -was first used in 1954 by a pathologist, Dr A. M. Barrett, to describe the unexpected death of an apparently healthy infant. In 1969 a paediatrician in the USA, Dr J. B. Beckwith, gave cot death the more formal name of sudden infant death syndrome, which is often abbreviated to SIDS. Whatever it was called, it appeared to be becoming more common, and not only in the UK and the USA, but throughout Western Europe, Australia, and New Zealand. Strangely, there were almost no cases in other parts of the world, such as China, India, Africa, and Japan, although babies of Japanese parents in the USA were just as likely to die this way as those of other ethnic groups. It was assumed that cot death was linked to infant care practices or to something in the home environment.

In the 1970s and 1980s cases of SIDS became more and more common, until by the late 1980s it was accounting for around a third of all the deaths among babies under the age of 12 months. In England there were about 20 such cases a week, and these were deaths identified as SIDS rather than being attributed to natural causes, such as an unidentified infectious disease, or accidental suffocation. Something clearly must be causing them, but what? Various suggestions were put forward to explain this type of death, such as an extreme allergic reaction to cow's milk. Another was that babies were more at risk when the parents smoked and that this was somehow responsible. A few commentators with a mystical bent even thought that nearby power lines caused cot death.

In 1990 the hypothesis that the deaths were due to antimony poisoning by stibine hit the headlines in a big way, especially in the UK. According to proponents, the gas was being given off by the fungus Scopulariopsis brevicaulis breeding on the antimony oxide fire-retardant in the PVC of cot mattresses. This microbe flourishes in damp conditions as we saw in Chapter 6, and what Scopulariopsis brevicaulis could do in making arsenic volatile, it might also do with antimony. What we were witnessing was the antimony version of Gosio's disease. The fungus appeared to be breeding on urine-damped mattresses and giving off the equally deadly stibine gas.

The two men who came up with this hypothesis in 1988 were Barry Richardson, an independent materials consultant and director of Penarth Research International, in Guernsey, and a friend Peter Mitchell, who lived in Winchester, in the south of England. At first they believed that arsenical fire-retardants were being used to protect the PVC used to cover cot mattresses and that it was arsine that was causing SIDS. They obtained several such mattresses from various police forces around the country and began to test them to see if this gas was being emitted from them, but none was detected. Instead they thought they had discovered that stibine was being released. They detected and identified it by using dampened silver nitrate test papers, which turn black when exposed to this gas.

Other aspects of cot death seemed to fit the theory. The apparent increase in cot deaths coincided with the introduction of PVC-covered cot mattresses, and its occurrence was only likely to happen in those countries where these were used. In Japan, for example, babies were put to bed on cotton futons that were treated with borate fire-retardants, and in that country cot death was not a recognized problem. What really convinced Richardson and Mitchell that they had stumbled on the cause of cot death was the discovery that cot death babies had higher levels of antimony in their blood. They wrote about their hypothesis and their supporting scientific evidence in a paper which they sent to the British Medical Journal, but the editor refused to publish it because they had breached one of the journal's guidelines, that there should be no publicity prior to publication.

What Richardson had done was to contact a reporter on the BBC Radio 4 programme You and Yours, which went out at midday, and its producers had alerted the editors of the early morning programme Today, who were happy to carry the story and to interview Richardson. So it was on the morning of June 1989 that the British public learned about Richardson's belief that cot death was due to the chemical antimony oxide in cot mattresses. Richardson was finally able to publish his hypothesis in the Lancet in 1990 (Vol. 335, p. 670) in which he claimed that on all the baby mattresses he examined he could detect Scopulariopsis brevicaulis and he assumed the gas which this microbe was generating was stibine.

Newspapers took up the story and such was the concern they generated that the UK Government felt obliged to take action, which it did first by commissioning the Laboratory of the Government Chemist to confirm Richardson's findings. This they were unable to do, but that piece of negative evidence counted for naught in the face of media clamour for something to be done. So, on 9 March 1990, the Government announced an official inquiry which would be carried out by a group of experts headed by the late Professor Paul Turner of the prestigious St Bartholomew's Hospital in London. He was the chairman of the Government's advisory committee on toxicity.

The committee reported 14 months later, in May 1991, and concluded that there was no scientific evidence to support Richardson's hypothesis, although the Government did take on board one of Richardson's suggestions, which was that parents should not place their baby on its stomach when laying it down to sleep. He thought this would reduce the amount of stibine from a damp and infested mattress being inhaled by the baby. The Department of Health launched a 'Back to Sleep' campaign in December 1991 which advised parents to lay their babies on their backs. As a result of this advice the number of cot deaths, which were already declining from a peak of almost 1500 in 1988, began to fall even faster and by 1993 were down to around 420 cases. The issue of cot death still had a very high national profile, and became major news when Sebastian, the 4-month-old son of popular television presenter, Anne Diamond, was found dead in his cot one morning.

One of the investigators approached by the Turner committee was Joan Kelley who had been asked by the Department of Health to examine cot mattresses for microbes, she had inspected 50 such mattresses, on 19 of which a cot death had occurred. Altogether she found many kinds of microbes, including the much more dangerous Aspergillus fumigatus fungi, but only on three mattresses could she detect Scopulariopsis brevicaulis. She concluded that there was no evidence that this microfungus could be linked to SIDS.

Richardson and Mitchell were fast losing credibility by this time, but then on 17 November 1994, The Cook Report, a popular and influential television programme, devoted itself entirely to their hypothesis. A new media scare erupted and soon there was widespread alarm. The report was called 'The Cot Death Poisoning' and it vindicated Richardson's theory. A helpline set up by the TV company that broadcast the programme received 50 000 calls from worried parents, who began throwing away their cot mattresses. It did not seem to matter that Richardson's theory had been shown to be wrong and that leading experts were criticizing the programme not only for its alarmist tone but also for its lack of scientific content.

Nevertheless, post-mortem analyses were showing that cot death babies had higher than expected levels of antimony and these analyses were scientifically sound, having been carried out by respected scientist Dr Andrew Taylor, of the Robens Institute of Industrial and Environmental Health and Safety at the University of Surrey. He had analysed the blood of 37 SIDS

babies and found antimony in 20 of them with an average level of 0.07 ppm. Among 15 babies who had died from other causes he found antimony in only one and this had less than 0.0005 ppm. This evidence appeared to indicate a significant link between antimony and risk of cot death.

A second edition of The Cook Report was broadcast two weeks later on 1 December, and this gave the new evidence that cot death victims had higher levels of antimony than other babies who had died of other illnesses. In the eyes of many it seemed to confirm that stibine really was responsible for cot death, and this had to be coming from the PVC covering of cot mattresses. Suspect mattresses were dumped in their thousands.

In response to The Cook Report, shops that sold such mattresses quickly removed them from their shelves, despite the fact that several manufacturers of cot mattresses had already taken action in response to the first stibine scare in 1991 by removing all arsenic and antimony-based fire-retardants from their products. Some had even gone over to using polyurethane foam that contained no phosphate fire-retardant either. The UK Government's response to The Cook Report was to set up another investigation: the UK Expert Group on Cot Death Theories. This time the investigation would be even more thorough, and it was chaired by no less a person than Lady Sylvia Limerick, Vice-Chairperson of the Foundation for the Study of Infant Deaths. She would guarantee that all sides of the issue would be addressed and experimental research would be commissioned and funded via the Department of Health.

Other researchers were directed to look more closely at the stibine theory, and at London University's Birkbeck College, a microbiologist, Dr Jane Nicklin, and a chemist, Dr Mike Thompson, carried out a series of experiments. Nicklin cut up SIDS mattresses and placed samples in conditions that would allow Scopulariopsis brevicaulis to flourish and Thompson analysed the gases given off to see if stibine was evolved: it wasn't. Meanwhile the Scottish Cot Death Trust commissioned an investigation by researchers at the Royal Hospital for Sick Children in Glasgow and they found that the livers of SIDS babies had lower levels of antimony than those of infants who had died of other causes. At Liverpool University, Professor Dick Van Velsen analysed hair samples from cot death babies and found that the hair that had grown on babies while they were still in the womb had more antimony than that which grew after birth, which again seemed to disprove the theory that the antimony was coming from mattresses. An epidemiological survey carried out by Professor Peter Fleming of the Institute of Child Health at the Royal Hospital for Sick Children in Bristol came to the conclusion that PVC-covered mattresses were less likely to be associated with cot death.

In its 9 December 1995 edition, the Lancet carried a long article from a group headed by Dr David Warnock at the Public Health Laboratory in Bristol. The group had been asked by the Limerick committee to test PVC mattress covers; it tested 23 and found that while most contained antimony oxide (generally 0.7-1.5%, although one had 3%) some contained only trace amounts. Richardson had willingly collaborated with this group and they had carefully repeated his analyses of PVC mattress covers, but they came up with very different results: the microbes that grew on the incubated PVC were not Scopulariopsis brevicaulis but a species of Bacillus, a common environmental bacteria, and the gas they gave off was not stibine but a sulphur compound, although it, too, turned the silver nitrate test papers black, just as Richardson had observed.

The Lancet in which these results were reported acknowledged that Richardson had tested his theory within the limits of his resources, but in 1989 he had been misled and misinterpreted what he had observed. The same issue also carried a letter from Mike Thompson, who had carried out tests on nine mattress covers that contained antimony, and while he, too, could get fungi to grow on them, including a little Scopulariopsis brevicaulis, there was no indication that any stibine was emitted, and he had looked for this using advanced analytical techniques (inductively coupled plasma mass-spectroscopy) that would have detected minute amounts had it been present. In 1995, a BBC TV programme, QED, sponsored a repeat of the Richardson experiments and those of Thompson, and again no stibine could be detected.

The stibine issue was debated in the letter columns of the Lancet, with Richardson making claims that there was a link between SIDS and mattresses, while others said that this was not so. The media bandwagon rolled on, with some newspaper columnists firmly supporting the Richardson theory, and belittling those who criticized it. It was even unfairly suggested that the new committee set up by the Government, headed by Lady Limerick, had rejected the Richardson theory in advance and so could not be expected to deliver an independent verdict.

The issue refused to go away and newspapers continued to carry articles saying that stibine was the main cause of cot death. The book The Cot Death

Cover Up by Jim Sprott, a consultant chemist and forensic scientist, was published in New Zealand, although it was not a scientific work as such because it gave no references to the sources on which its author made his allegations. Sprott was also part of the Campaign Against Cot Death in that country, where BabeSafe mattresses and mattress covers that were free of all antimony, arsenic, and phosphorus compounds were being sold, which he endorsed. His newsletter Cot Life 2000 claimed that his warnings and advice about the dangers of stibine had led to a striking decrease in the incidence of cot death in New Zealand.

Researchers in the UK at De Montfort University, Leicester, led by Professor Peter Craig, were commissioned by the Limerick committee to carry out intensive research into Scopulariopsis brevicaulis and its ability to form volatile compounds with inorganic antimony. For the first time ever, they found that this could generate a volatile product of antimony, but that it was trimethylstibine, not stibine. (Trimethylstibine has three methyl groups (CH3) attached to an antimony atom.) However, when the antimony oxide was incorporated into the PVC of a cot mattress on which the microbe grew, not even this volatile compound was formed.

The mystery of where the antimony in babies was coming from was finally revealed in March 1997. The Lancet carried news of the research by Mike Thompson, done jointly with Ian Thornton, of Imperial College London, and which had been published in Environmental Technology (Vol. 18, p. 117). It reported his analysis of samples of household dust collected at random from 100 homes in Birmingham (an industrial city), Brighton (a seaside town), Richmond (an outer suburb of London), and Westminster (inner London and the seat of government). All showed unexpectedly high levels of antimony of between 10-20 ppm, compared to the background level of antimony in the Earth's crust of only 0.2 ppm. (In a few homes, the levels of antimony in dust were in excess of 100 ppm and in one home in Birmingham it was an incredible 1800 ppm.) Thompson and Thornton pointed out that the level of antimony in the livers of cot death children was only 0.005 ppm, and that this amount could easily have come from the ingestion of household dust. The amount of dust a baby ingests is thought to be around 100 mg/day, which for most babies would give them around 1 ^g of antimony. The antimony in a home was correlated to the amount of lead in the dust, suggesting that this was where it was originating.

The news was carried by several newspapers, who questioned its reassuring message about antimony because this still appeared to conflict with other data which were given in the book by Sprott. Other results, however, were now appearing that tended to clear antimony of the charge of causing cot deaths. The analysis of the urine of 148 young babies at the Great Ormond Street Hospital for Children in London showed that antimony was even present in babies tested within 24 hours of birth when clearly cot mattresses could not be to blame. The antimony was almost unmeasurable but nevertheless it was detectable.

Then, in May 1998, the final report of the Limerick committee, which went under the name of The Expert Group to Investigate Cot Death Theories: Toxic Gas Hypothesis, was published. It refuted all the arguments that had been put forward regarding stibine and SIDS. It pointed out that cot mattresses were rarely contaminated with Scopulariopsis brevicaulis, that there was no evidence that stibine was generated by cot mattresses, and that hundreds of experiments had been carried out to test whether this could occur. (This report did say that under laboratory conditions it was possible to convert antimony oxide to trimethylstibine.) It pointed out that there was no clinical evidence that any SIDS baby had died of stibine poisoning; that antimony was present in the majority of infants and was no higher in cot death babies than other babies; that the introduction of antimony oxide fire-retardants in mattress covers in 1988 had not led to an increase in cot deaths, nor had its removal in 1994 led to a decrease. All of these conclusions were backed up by experts in the field. The Limerick study had cost £ 500 000 and had taken three years to complete, but this was felt to be justified if it could show one way or the other whether stibine might be the cause of cot death.

Media coverage of the Limerick report was far less than that given to the earlier scare stories. Some newspapers interviewed those who had been on the firing line as a result of The Cook Report. They were scathing in their condemnation of the programme, calling it irresponsible and pointing to the unnecessary distress it had caused parents of babies and young children. One popular newspaper the Sunday People even suggested that Carlton Television, which produced it, should have its licence removed. Joyce Epstein, Secretary General of the Foundation for the Study of Infant Deaths, referring to the Limerick report, summed up the years of needless worry and misdirected effort by approving the report's findings, saying that it brought to a close 'a ghastly episode in public health scare mongering'.

Despite the reassurance of the Limerick report, researchers continued to check whether SIDS babies really had raised levels of antimony in their bodies but the evidence was that they did not. A particularly intensive study of Irish cot death babies was organized by Professor T. G. Matthews at the Children's Hospital, Dublin. He analysed antimony levels in liver, brain, blood, and urine in all 52 cot death babies that died in Ireland in 1999 and compared these levels with those in babies who died of other causes. In all the babies the level of antimony in tissue was less than 0.01 ppm, and the same in both SIDS and non-SIDS babies. Antimony levels in blood were around 0.3 ppm, with SIDS babies being fractionally higher, and in urine levels were around 3 ppm, but with no difference between SIDS and non-SIDS babies. The conclusion was that there was no evidence to support the theory that SIDS was caused by antimony. Indeed there is still no simple explanation for many of the cases of cot death.

It is likely that the cot death scare will be the last example of public concern regarding the use of antimony. Although this element has a valuable contribution to make to certain materials, it need not be an important part of the domestic environment, and where it might be used it is unlikely to affect human health. Insofar as much of the antimony that is used is added to strengthen lead, the limits now imposed on the use of this metal will likewise impose a similar limit on the use of antimony. If there is a future for antimony then it is likely to be in the form of new drugs to treat old diseases, but even in the fight against human parasites such are the safety requirements which all new drugs must meet that it is unlikely that any that are introduced will cause harmful side effects.

Antimony will forever be a part of the world around us but at the end of the day it is a toxic element and nothing can ever alter that. What antimony can sometimes do is provide forensic evidence that would otherwise be unobtainable and thereby help solve a crime. It provided valuable insight into the murder of the most powerful man in the world, as we shall see in the next chapter. It even solved the mystery of how Brazilians were drinking much more Scotch whisky than the Scots were exporting to them.

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