Monday, July 14, 2008
Professor Peter Fleming (University of Bristol) will address the conference. Dr Fleming and UK FSID promote the 1998 UK Limerick Report, which concluded that the toxic gas theory for cot death was unsubstantiated.
For an overview of errors and fallacies in the Limerick Report, click on www.cotlife2000.co.nz/limerick.htm
“In 1989 Mr Barry Richardson, a materials consultant, said that his research showed antimony added to mattress PVC released a toxic gas which, he said, caused cot death. In 1990 the Department of Health and FSID commissioned studies to investigate the claim but neither found any evidence to support it."
Wrong. The 1990 UK Department of Health investigation (Turner Report, May 1991) did find evidence to support the toxic gas theory: the Turner Committee achieved biogeneration of a form of stibine gas from cot mattress material. Furthermore, the Committee recommended that if antimony fire retardant was used in cot mattresses, the levels of arsenic in the antimony should be as low as possible - a tacit admission that mattresses could generate arsine gas.
“There is no difference in antimony concentrations in cot death babies and other babies."
Wrong. Research carried out in Britain in 1994 (by the Robens Institute Trace Element Laboratory, Surrey) showed that post mortem body tissue of cot death babies contained many times more antimony than tissue of babies who had died of other causes. (FSID’s incorrect claim resulted from their citing average figures, whereas for such purposes individual figures must be used.)
“Antimony is found in most babies and was reported in scientific literature before the chemicals were present in mattress PVC. Antimony is found in babies even before birth - i.e. before they could have had any exposure to mattresses. It could come from maternal diet, but antimony is everywhere in the environment, including common household dust.”
Wrong. Antimony is a very rare element. It comprises about one part per million (0.0001%) of the earth’s crust. In the household environment antimony is present in significant quantity only in polyvinyl chloride (PVC) sheeting and certain upholstery and bedding. Chemical analyses of a range of food and other materials were carried out in Britain in 1994, and antimony was found to be virtually absent.
"Antimony was not added to mattresses in the UK before 1988 and yet cot deaths were occurring at the rate of about 2,000 per year well before then. There are currently just under 350 cot deaths per year. The year after antimony was first added to mattresses, 1989, was the year that cot deaths began to decrease."
First sentence wrong; third sentence misleading. The facts are as follows: Antimony was first introduced into cot mattresses in Britain in the early 1950s, and the British cot death rate increased steadily from that time onwards. The highest cot death rate in Britain (2.3 deaths per 1000 live births in 1986-1988) occurred at the same time as the highest concentration of antimony in cot mattresses. The British Government had required fire retardant to be incorporated into cot mattresses by 1988. Manufacturers were given four years’ notice, and during this period moved towards compliance with the new standard.
Certainly the British cot death rate fell while the amount of antimony in mattresses was high; but that was because from mid-1989 onwards British parents took preventive measures against toxic gas generated in babies’ mattresses; and furthermore, British manufacturers began to remove antimony from cot mattresses.
In June 1989 the toxic gas theory for cot death was publicised nationwide in Britain, and parents were advised to use a new mattress for each baby, or alternatively to wrap their existing mattress in polythene sheeting. The cot death rate immediately began to fall; and it had fallen 38% by the time the British “Back to Sleep” (face-up sleeping) campaign was introduced in December 1991 (two-and-a-half years later).
"The claim that the decrease [in the cot death rate] was due to publicising the advice to wrap mattresses is unfounded. In the CESDI study (Confidential Enquiry into Stillbirths and Deaths in Infancy), the UK's largest study into cot death, only 2% of mattresses in the UK were found to be wrapped, and the study found that babies had actually died on wrapped mattresses. The claim by Cot Life 2000 that this is because the mattresses were wrapped incorrectly is unsubstantiated. As CESDI is a confidential enquiry with the data being completely anonymous, it is not possible for anyone to know whether the wrapping was ‘incorrect’."
First part irrelevant; second part wrong. As stated above, the advice publicised in Britain in June 1989 was that parents should use a new mattress for each baby or alternatively wrap their existing mattress in polythene sheeting. It is quite clear that many parents took the first option: sales of new cot mattresses jumped by around 15%. Thus FSID’s statement that only 2% of mattresses were wrapped is irrelevant - many parents took the option of buying a new mattress instead.
FSID’s claim that babies in the CESDI Study had actually died on mattresses wrapped for cot death prevention is totally unsubstantiated. No chemical analysis of the plastic wraps in question was carried out. In February 2000 Professor Peter Fleming (an author of the CESDI Study) conceded on Radio New Zealand that he could not demonstrate that the mattresses in question had been wrapped in accordance with the specifications for cot death prevention.
"Cot death occurs in countries where no antimony has ever been added to mattresses.”
Of course it does. Antimony is naturally present in various materials used for infant bedding (e.g. sheepskins); furthermore, antimony is used as a catalyst in the manufacture of PVC and other materials used as mattress components. Therefore antimony can be present in infant bedding (and result in cot deaths) even though it has not been added during the bedding manufacturing process. FSID's statement is irrelevant.
"When comparing babies who die with those who live, proportionately more of the babies who lived slept on PVC mattresses. This may be because it is easier to keep such mattresses clean. A Scottish study found that previously used cloth or ‘ventilated’ mattresses (which are more difficult to keep clean) are associated with an increased risk of cot death. However, the same study found that used mattresses with a full integral PVC covering were not associated with an increased risk of cot death."
Misleading. Provided PVC does not contain any phosphorus, arsenic or antimony, it is an excellent mattress covering. Following the nationwide publicity about the toxic gas theory in Britain in June 1989, mattress manufacturers began removing those chemicals from PVC used to cover cot mattresses - so of course the cot death rate on PVC-covered mattresses in Britain went down.
"Several research groups have replicated Mr Richardson's original experiment but their findings do not substantiate his conclusions, even though Mr Richardson co-operated fully with one of the attempts and agreed that the same methodology had been followed. In other words, in normal cot-like conditions it is not possible to generate toxic gas from antimony encapsulated in mattress PVC."
Wrong. The UK Turner Committee (which investigated the toxic gas theory in the early 1990s) proved the gas generation concerned. In the case of the Limerick Committee’s investigation of the toxic gas theory, at the only meeting held between Barry Richardson and the Committee’s researchers, Richardson warned the researchers that their test methods were incorrect. A technical critique published by Richardson following the release of the Limerick Report (in 1998) demonstrates that the Limerick Committee did not replicate his test methods.
The former Chief Executive of the New Zealand Cot Death Assocation, Mr Lee Schoushkoff, conceded that the Limerick Committee did not replicate Richardson’s test methods.
And in any event, the Limerick Committee achieved the generation of the highly toxic gases stibine and arsine from cot mattress materials.
For information on how to prevent cot death (by preventing exposure of babies to the toxic gases which cause cot death), visit www.cotlife2000.co.nz
T J Sprott OBE MSc PhD FNZIC
Consulting chemist & forensic scientist
10 Combes Road
Auckland 1050New ZealandPhone: +64-9-5231150e-mail: firstname.lastname@example.org
On Tuesday at the SIDS 2008 Conference (Portsmouth):
New Zealand researchers Professor Barry Taylor and Dr Sally Baddock will participate in conference proceedings.
If mattress-wrapping did not prevent cot death, by now hundreds of cot deaths would have occurred in New Zealand on "wrapped mattresses". But during the 13 years since mattress-wrapping commenced, no such death has been reported.
Furthermore, New Zealand Professor Ed Mitchell's research published in the European Journal of Pediatrics (1) in February 2008 demonstrates the efficacy of mattress-wrapping in preventing cot death (SIDS).
Since the commencement of mattress-wrapping in 1995, in "Case-Control" terms there have been two groups of babies in New Zealand:
Babies who slept on wrapped mattresses: Case babies
Babies who did not sleep on wrapped mattresses: Control babies
Statistical analysis (using Dr Mitchell's data):
Total number of live births in New Zealand from 1995 to 2007 (inclusive): 748,300
Using an incidence of mattress-wrapping of 21.7% (as reported in Dr Mitchell's research):
Number of Case babies: 748,300 x 0.217 = 162,380
Number of Control babies: 748,300 x 0.783 = 585,920
Cot deaths in New Zealand from 1995 to 2007 (inclusive): Around 860 (2)
Reported cot deaths among Case babies (babies who slept on wrapped mattresses): Nil
If mattress-wrapping had nil effect on the incidence of cot death, the number of cot deaths among the Case babies would have been: 860 / 585,920 x 162,380 = 238
Since there has been no cot death among the Case babies, the efficacy of mattress-wrapping in preventing cot death was in the ratio 238 / zero.
However, there is no meaningful solution to the equation x = a/zero where "a" is a real number. This situation is overcome by positing that the number of cot deaths among the Case babies was "very much less than 1”, denoted by the nomenclature <<1.>>1 means “very much greater than 1”.)
Using this nomenclature, the ratio of effectiveness of mattress-wrapping in preventing cot death is:
Effectiveness = 238 divided by <<1,>>238
Thus in statistical terms the efficacy of mattress-wrapping in preventing cot death is: Very much greater than 238 times the efficacy of all other items of cot death prevention advice combined
See http://www.cotlife2000.co.nz/ for further information
1. Eur J Pediatr 2008; 167(2): 251-252. A postal survey conducted among 400 Auckland (New Zealand) mothers regarding practices adopted for cot death prevention reported the incidence of mattress-wrapping as 21.7%.
2. Source of statistics: New Zealand Ministry of Health.
T J Sprott OBE MSc PhD FNZIC
Consulting chemist & forensic scientist
10 Combes Road