Tuesday, October 21, 2014
The great phthalate scare rumbles on
The study described below is an unpublished one so is difficult to evaluate fully. There is enough detail below to question its conclusions, however. It is established that phthalate exposure can be increased by eating certain foods, "junk" food in particular. But since the toxicity is in the dose nobody knows if the amounts concerned are cause for alarm
So the study below looks important. We do appear there to have evidence of harm: Higher levels of serum phthalates were found to go with decreased libido.
But as I have pointed out many times, correlation is not causation and the fact that it was not phthalates behind the loss of libido can very readily be inferred from the fact that working class people, particularly poor people, are much more likely to eat "junk" food than are middle class people. And as has been shown just about whenever it is examined, working class people have poorer health. And that loss of libido might be one aspect of poor health scarcely needs stating.
So phthalate levels were simply a proxy for social class and it was social class behind the lower levels of libido, not phthalates themselves.
All that is fairly obvious so poverty should have been the first thing controlled for in the study. Was it? I would be surprised. I would be surprised if income was even asked of the patients. We will have to wait for the study to be published before we know, however. Given the ubiquity of class effects, however, a class effect has to be the default interpretation of the results. Evidence that phthalates are harmless is summarized here
Chemicals found in PVC flooring, plastic shower curtains, processed food and other trappings of modern life may be sapping women’s interest in sex.
A study has linked low libido with the additives used to soften plastics which are found in every home.
Women with the highest levels of phthalates in their bodies were more than twice as likely to say ‘not tonight dear’ as those with the lowest amounts.
Phthalates are man-made chemicals thought to interfere with the natural hormones that are crucial to overall health.
They are found in everything from PVC flooring and shower curtains to car dashboards – and may also be in our food. Tiny particles can enter our systems either through breathing or eating.
Previous studies have linked them to diabetes and asthma. They have also been blamed for feminising the brains of baby boys and last year the World Health Organisation warned they have ‘serious implications for health’.
The latest research, presented at the American Society for Reproductive Medicine’s annual conference in Honolulu, suggests they are doing psychological, as well as physical, damage.
In the first study of its kind, Dr Emily Barrett, of the University of Rochester School of Medicine in the US, measured levels of phthalates in the urine of 360 pregnant women in their 20s and 30s.
She also asked them how often they lost interest in sex in the months leading up to their pregnancy.
Those with the most phthalates in their bodies were two and a half times as likely to say they had frequently lacked interest in sex as those with the least.
Dr Barrett suspects that phthalates interfere with the production of sex hormones oestrogen and testosterone, both of which are involved in female libido.
She said that food is a significant source of phthalates, particularly processed and highly-packaged products. It is thought to get into into food from processing equipment and from packaging.
Dr Barrett, who tried to avoid fast food when pregnant over fears that the chemicals it contains would harm her unborn baby, said: ‘One of the recommendations... to potentially lower your exposure is to eat less processed food and to pick fresh things without packaging.’
A spokesman for the Chemical Industries Association, which represents manufacturers, said: ‘We are not aware of any globally accepted tests which can yet measure the effect chemical exposure may have on libido.’
He added that phthalates are among the most researched chemicals and the use of any that affect fertility is restricted.
Certain phthalates are banned from use in cosmetics, toiletries and toys in the EU and further restrictions are due next year.
Posted by John J. Ray (M.A.; Ph.D.).