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Something in plastics may be weakening kids’ teeth
Before Reading:
1. What is the source of pollutants that can taint the environment? That is, how do those materials enter the
environment? What are their sources?
2. In what ways can plastic pollute the environment? How does it get there? Can people become exposed?
--------------------------------------------------------------------------------------------------------------------------------------------------During Reading:
1. What is enamel and what role does it play in teeth?
2. What share of children show enamel defects, according to Sylvie Babajko?
3. What are hormones and what do they do?
4. What are two of the hormones that affect tooth development?
5. What’s another name for androgens?
6. What is vinclozolin?
7. What is BPA and name four things in which it is used?
8. Androgens and estrogens are also involved in what other part of the body, according to Frederick vom Saal?
-----------------------------------------------------------------------------------------------------------------------Article:
Over the past two decades, the share of children with defective tooth enamel has been rising. And BPA, a chemical
used to make many plastics, could be partly to blame. That’s the finding of a new study in rats. It showed that this
pollutant can trigger the same problem in lab animals that had been showing up in the kids.
Enamel is the hard substance that covers a tooth. If it does not form properly, a child can develop cavities and other
problems. A dentist can repair these defects. But there is no way to fix the altered gene instructions responsible for
making the enamel weak in the first place.
This enamel defect “now affects 15 to 20 percent of children six to nine years old,” says Sylvie Babajko. She is a
molecular biologist at INSERM. It’s the National Institute for Health and Medical Research in Paris, France. This defect
affects different numbers of children in different places. In some parts of the world, as many as 40 percent of children
may have this weakened enamel, she notes. But where it’s been studied well, about 1 in 6 kids (18 percent) are affected.
Babajko, Katia Jedeon and their team are studying this failure of kids’ tooth enamel to form correctly. The problem
affects both molars and incisors (teeth in both the back and front of the mouth). The teeth end up with white milky
spots. They are caused when the mineral structure of the teeth develop weakened regions. These are defects. The
problem develops when teeth are first forming, Babajko notes.
The problem is not new. But it has been showing up in more and more kids. And the increase emerged at the same
time as did other health problems linked to a specific group of chemicals, she notes. Such chemicals are known
as endocrine disruptors.
In their new study, the researchers traced the weakened enamel in their rats to pollution-altered genes. Those
genes instruct cells on how to build a tooth. Babajko’s group reported its findings on May 31 at the 18th Congress of
European Endocrinology. It was held in Munich, Germany.
Confusing the body’s hormone system
Hormones are part of the body’s endocrine (EN-doh-krin) system. They control the timing of pivotal actions — from
how organs form and how cells use energy to how the brain works and how the body prepares for reproduction. In
some cases, pollutants can block or slow the action of hormones. Other times, these pollutants can masquerade as
hormones. Either way, these endocrine disruptors can do a lot of damage by throwing off the timing of when the body
turns important actions on or off.
Two types of hormones — estrogens and androgens — play a role in directing the cells that make tooth enamel.
Estrogens are known as female sex hormones. Androgens are male sex hormones. Both types of hormones play
important roles in how the bodies of all young mammals develop. Their effects start in the womb and continue on
through puberty and adulthood.
Over the past few years, Jedeon and her colleagues found evidence that two pollutants could promote defects in
enamel. Both were androgen disruptors.
One chemical was vinclozolin (Vin-KLOH-zuh-lin), a fungi-killing chemical. It can block the action of the androgen
known as testosterone. But aside from farm workers, most people don’t encounter this chemical.
The other pollutant, BPA, is far more common. Short for bisphenol (Bis-FEE-nawl) A, this chemical can mimic the action
of estrogen. It also can disrupt the action of testosterone. Manufacturers use BPA to make everything from eyeglasses
and kitchen bowls to dental sealants. A coating on many papers, BPA rubs onto hands from the paper used to print
many store receipts. BPA also coats the inside of many food and drink cans and jar lids. Some 16,000 different food and
drink products use BPA in their packaging. Most people have broad exposure to this chemical.
Although the INSERM studies had linked exposures to both chemicals with impaired enamel formation, the
researchers did not know precisely what was going wrong. So for their latest study, they decided to home in on genes
of enamel-making cells.
Of genes and androgens
Kids may be most vulnerable to BPA very early in life, Babajko says. This would be from when their baby teeth first
begin to form until about age four or five. So for its new study, Babajko’s team exposed pregnant rats to either BPA or
vinclozolin. Once the babies were born, those pups were exposed for another month. The researchers then examined
cells and their genes in those pups.
BPA and vinclozolin both altered a small group of genes, the data show. These genes are directly involved in the
enamel-making of teeth. What’s more, these genes are especially vulnerable to changes in androgens. As a result,
Babajko now concludes, BPA and such androgen-disrupting chemicals may be “leading to the weakening of enamel
quality.”
The results also suggest these tooth defects could be used as a signal that a child has been exposed to a hormonedisrupting chemical, she adds.
Many cells and body parts that these chemicals might affect have not yet been studied, says Andrea Gore. This is
because they’re not usually considered to be part of the endocrine system, she explains. Gore is an endocrine expert at
the University of Texas at Austin. The new study, she says, suggests that hormone-disrupting chemicals may be
affecting parts of the body that have not yet been studied for these effects.
“Teeth certainly fall into that category,” she says. If tooth development involves these hormones, then they may be
vulnerable to impacts from chemicals like BPA, she says.
Frederick vom Saal studies hormone-mimicking pollutants such as BPA at the University of Missouri in Columbia.
Androgens and estrogens are involved in how the body uses calcium to make bone, he explains. Similar processes are
involved in producing tooth enamel. So it is possible that a hormone-disrupting chemical such as BPA could disrupt
enamel-making in teeth. And the cells Babajko’s study examined do interact with such hormones, he adds.
“One of the things we know about these [hormones] is that they are involved in all kinds of stuff you wouldn’t
necessarily expect,” says vom Saal. What’s more, these hormone-mimicking pollutants can affect people and lab
animals in very similar ways. So, what was seen in this study could “point us to [the cause behind] something that is a
significant public health issue for a substantial number of children,” he says.
It is not yet possible to know for sure if BPA is responsible for weakened tooth enamel and resulting cavities. But
scientists say that there is enough evidence to make further research important.
After Reading:
1. Perform some research so that you can make a chart of things that are made from BPA. Are there alternatives for
all of these items that do not contain BPA?
2. A number of government agencies are looking to ban certain classes of products that contain BPA. Do some
research to identify what the health concerns are that prompted those actions?