Plastics that are "BPA-free" may not be better for you, say researchers,
who have found that the replacement chemical, bisphenol S, has similar
effects to the discredited bisphenol A. The findings are published in
the journal Endocrinology.
When used in food containers and tableware, BPA is known to leach into food, particularly when hot.
In the last 20 years, the US has seen a rise in the number of premature human births and a rise in early puberty.
Previous studies have linked these problems with endocrine-disrupting
chemicals, and BPA has come under fire due to indications that it mimics
the effects of estrogen.
To counter this, a "safer" version has come onto the market, in which BPA is replaced with bisphenol S (BPS).
More than 5 million tons of products containing BPS and BPA were expected to be produced in the US and Europe in 2015.
Now, new studies into the brain cells, growth-related genes and organs
involved in reproduction suggest that BPS speeds up embryonic
development and disrupts the reproductive system.
Senior author Nancy Wayne, and colleagues at the University of
California-Los Angeles (UCLA), wanted to find out what effect low levels
of BPA and BPS would have on zebrafish. The levels tested were
equivalent to those found in polluted river water.
The team used zebrafish, because they have transparent embryos, making direct observation of cell growth possible.
Exposure to BPA and BPS leads to endocrine disruption
Fluorescent-green protein tags were used to track the development of
reproductive endocrine brain cells, the cells that control puberty and
fertility.
Physiological changes were seen in the embryos after just 25
hours, and the number of endocrine neurons increased by up to 40%,
implying an overstimulation of the reproductive system as a result of
BPA exposure.
The brain cells that control reproduction in the embryos and the genes
that control reproduction later in life were significantly affected. BPS
and BPA exposure led to similar results, suggesting that neither is
safe.
Moreover, after BPS and BPA exposure, egg development and hatching
occurred much faster than they would naturally, causing the equivalent
of premature birth.
Wayne believes that premature puberty and disruption of the reproductive
system could be the result of overstimulation of the neurons that
regulate reproduction.
The team also found that BPA and BPS affect both the estrogen system and
the thyroid hormone system. As the thyroid hormone has an important
influence on brain development during gestation, the findings would seem
to imply a greater risk for embryonic and fetal development in general.
Wayne says:
"Our findings are frightening and important. Consider it the aquatic version of the canary in the coal mine."
If animals are affected this severely by BPA and BPS, she says, the risks are likely to extend to human health, too.
Wayne immediately replaced all her own plastic food containers with
glass ones after making her first discovery about BPA in 2008, and her
family avoids plastic food containers where possible.
"Making plastic products with BPA alternatives does not necessarily leave them safer," she says.
Medical News Today has previously reported that other chemicals used in plastic food containers may contribute to hypertension.
Resource: http://www.medicalnewstoday.com
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