Mothers-to-be who use make-up are more likely to have fat children because the chemicals can reach them in the womb, a study claims.
Researchers measured levels of butyl paraben (BuP) in the urine of 629 mothers, finding higher concentrations in those who slapped on cosmetics.
Their babies were more likely to be overweight in the first eight years of their life – particularly girls.
Parabens are able to seep in the body through the skin, and then cross-over into the placenta with the risk of harming the baby, the scientists in Germany warned.
In further studies, baby mice exposed to BuP while in the womb were driven to eat more, becoming fatter than control mice.
BuP – also digested in food and drink – was found to impair genes that regulate food consumption in the mice.
Mothers-to-be who use makeup and perfume may worsen their child’s risk of obesity by exposing them to a chemical in the womb, a study warns
BuP is a chemical used as a preservative as it has anti-bacterial and fungicidal properties. It is found in most long-wear makeup products, such as lipstain or foundation.
It is one type of paraben, found in a host of beauty items, including makeup, deodorants, moisturisers and shampoos, as well as food products.
Parabens enter the human body mainly through ingestion or skin absorption and can commonly be detected in urine, blood and breast milk.
Researchers led by Dr Tobias Polte from the Helmholtz research institute in Leipzig reported their findings in Nature Communications.
The team looked at levels of the chemical in 629 pregnant women between 2006 and 2008.
The expectant mothers had been asked to fill in a questionnaire as to what cosmetics they used in the 34th week of pregnancy.
Cosmetics were categorised as leave-on products, including body lotion and make-up, and rinse-off products, including toothpaste, hairstylers and perfumes.
A quarter of women reported using at least one leave-on cosmetic product that contained parabens. Their urine contained paraben levels three-fold higher than women who said they avoided parabens.
The body weight and height of the children were then assessed on an annual basis up to the age of eight.
The authors found the mothers who used cosmetics containing BuP specifically had children who were more likely to be overweight in early to mid-childhood – with a ‘stronger trend in girls’.
The authors wrote: ‘As parabens are frequently used in cosmetic products, it seems reasonable that cosmetics are a principal source for human paraben exposure.
‘Mothers that used paraben-containing cosmetic leave-on products on a daily basis had significantly higher urinary paraben concentrations.’
In further research, the authors showed that exposure to BuP in pregnant mice led to their female offspring eating more.
Baby mice exposed to BuP had 20 to 45 per cent more body fat compared with control mice.
The authors claim that the paraben affects a gene which regulates food intake in the hypothalamus brain region.
There was a reduction in expression of the leptin receptor, which, under normal conditions, regulates body weight by balancing food intake.
In other words, because gene expression for the leptin receptor was impaired, the mice struggled to stop eating.
The authors say that sedentary modern lifestyles and increased calorie intake are not enough to explain obesity.
They argue that when a baby is in the womb, its development can be disrupted by chemicals such as parabens that disrupt hormones.
These are known as endocrine disrupting chemicals [EDCs], and are also linked to the growth of breast cancer cells.
Many of them are able to cross the blood-placenta barrier with the risk to exert their harmful properties already during foetal development, Dr Polte and colleagues said.
Commenting on the research, Dr Alex Polyakov of the University of Melbourne said mouse and human physiology were different, but he said pregnant women would be best off avoiding make up with paraben compounds.
He said: ‘At this time, it would be advisable for pregnant women to avoid cosmetic compounds that contain paraben.
‘Complete avoidance of paraben is not possible as its use is so widespread, but avoiding non-essential exposure seems like a prudent and easily achievable goal.’
However, Dr Amy Heffernan of Melbourne’s Florey Institute said the link between parabens and weight gain in children was ‘weak’.
She said: ‘Paraben exposure varies throughout the day and from one day to the next. A single urine sample is not a reliable measure of paraben exposure.
‘There was some very weak evidence of a link between high butyl-paraben exposure and the child being overweight two to eight years after birth.
‘Studies in mice are not the same as studies in humans. Diet and exercise are much more important than paraben exposure in healthy weight management.’