Vinyl flooring 'doubles chances of children being autistic', study shows
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Independent Minds
Children who live in homes with vinyl flooring have double the chance of being autistic, research has discovered. The finding – which amazed even the scientists conducting the study – provides one of the first clues as to a possible cause of the condition.
The study, by scientists in Sweden, Denmark and the United States, stumbled across the connection almost by accident. It is being taken seriously because autism has long been thought to result from environmental factors. Between 133,000 and 200,000 British children are thought to be autistic, but nobody knows for sure, or whether their numbers are increasing, because they are not counted. But the numbers of babies born with the condition in California has risen more than seven times in the past two decades, convincing scientists that pollution must be to blame.
The new research, which traced nearly 5,000 Swedish children from infancy to at least six years old, set out to investigate links between air pollution and asthma and other allergies. The scientists – from Karlstad University in Sweden, the universities of Rochester and Texas in America, and the Technical University of Denmark – identified the type of flooring in each home at the start of the study, but only started to look at autism later.
Their paper, published in the journal Neurotoxicity, describes the findings as "puzzling, even baffling, and not readily explicable at this time". But it adds: "Because they are among few clues that have emerged about possible environmental contributions to autistic disorders, we believe that they should be weighed carefully and warrant further study".
A possible explanation, they suggest, is that vinyl, or PVC, flooring produces dust full of phthalates, which are then breathed in. Experts who have reviewed the study believe that, if this is the cause, the children may have been most vulnerable when their brains were developing in the womb.
If this is so, the threat may come from more than just vinyl flooring. Californian research has also found high levels of the chemicals in wall-to-wall carpeting.
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Comments
Parents up and down the country are probably beating themselves up as we speak because they now think that their children's autism is the result of a moment of madness in the home furnishings department at John Lewis. In fact all that the authors of this study have found is that there is an association between vinyl flooring and ASD. That is light years away from saying that the former has actually caused the latter.
My confidence in Lean and Lakhani's reporting is not improved by the fact that they have got the name of the journal wrong (it's NeuroToxicology not Neurotoxicity) and they seem to have exaggerated the effect reported by the authors. If I am reading their data correctly they claim that 41 ASD children had vinyl flooring in their rooms (1.7% of the total sample) and that 25 ASD children had other types of flooring (1.2% of the sample). That is not "double the risk".
The original paper is perfectly sensible but, as the authors note
"At this time, we lack any firm knowledge about the extent to
which environmental chemicals or other environmental conditions
might influence the etiology or manifestations of ASDs. That
is, using the terminology of cancer risk assessment, do they act
primarily as initiators, or primary causes, or are they more like
promotors, simply enhancing or amplifying a process already
underway, or is it just a matter of confounding?"
When I am dictator of the world all science journalists will have the words "is it just a matter of confounding?" tattooed on the insides of their eyelids.
In other words (assuming I've now got it right) 1.7% of the children with PVC floors had ASD (that was 41 children with PVC and ASD), and 1.2% of the children with non-PVC floors had ASD (that was 25 children with non-PVC floors and ASD). So I still don't think that you can say that PVC is associated with a doubled chance of ASD. And you definitely can't say that the association is cause and effect.
We are surrounded by man made materials. No wonder there are so many people becoming allergic to the 21st century. Carpets, Vinyl floors, plastic soft drinks bottles, plastic food containers, additives, fertilisers, etc etc etc. There is seepage of low levels of chemicals into our food and breathing. So I can see that there is going to be an impact to humans.
Did you never hear the word " serendipitous"?
The authors of the study on which this article is based investigated several different factors to see if they had a statistically significant effect on the chances of a child developing ASD. These included the flooring in the child's room and also that in the parents' room.
No statistically significant links with the flooring in the child's room were found at all. There was a slight increase in ASD among the children with PVC floors, but this could have been simply due to chance. The authors also found no significant difference when they compared PVC flooring in the parents' bedroom with non-PVC flooring.
The only significant difference found was that children whose parents had PVC flooring in their rooms had an increased risk of ASD when compared with those who had wood floors.
There are at least three reasons to be cautious about reading anything into this.
The first is that it is odd that the effect was seen when looking at the parents' rooms but not the child's.
The second is that even if there is a genuine association between ASD and wood, as opposed to PVC, this does not necessarily mean that wood directly makes ASD less likely, or that PVC makes it more likely. An obvious alternative explanation springs to mind if you observe that wood floors are expensive, and PVC ones are not. So it may be parental income, rather than flooring that is responsible.
The third caveat centres around the concept of "statistical significance". The authors considered that a figure was statistically significant if the probability of it occurring by chance was greater than 1 in 20. Now a 1 in 20 probability is unlikely but by no means impossible. For example the chances of throwing two dice and getting a double six is less than 1 in 20, but if you throw the dice often enough it will eventually happen.
Similarly if you measure lots of different figures, as the authors of this study did, it is likely that you will come up with some figures which, has they been looked at individually would have seemed improbable.
I do not criticise the authors of the original study, because they were quite plainly aware of the potential shortcomings in their results. The Independent article however was irresponsible because it made the results look much vastly more meaningful than they in fact were.