Why wearing perfume and using plastic when pregnant can be harmful

Researchers fed pregnant mice cookies laced with chemicals found in plastics. Photo / Getty Images

Pregnant women who heat up food in plastic containers and wear perfume may be inflicting long-term damage on their unborn child's brain development, a new study on rats suggests.

A team at the University of Illinois baked cookies laced with phthalates, chemicals used in plastic and fragrances which are known to affect the way our hormones work, reported the Daily Mail.

They fed the cookies to pregnant and nursing mice - and found that, when their offspring reached adulthood, they were not as cognitively sharp as their peers who weren't exposed to the chemicals.

Lead author Dr Janice Juraska, a professor of psychology in the neuroscience department, told Daily Mail Online she was shocked by how clear the impact was, and said she would now urge pregnant women to avoid plastics and fragrances of any kind.

"We pay a price for the convenience of modern life. We need to work out when the price is too high," Dr Juraska said.

Dr Juraska, who has spent decades looking at how hormones affect our brain development and behavior, teamed up with her colleague Dr Susan Schantz who studies endocrine disruptors in modern products.

Dr Schantz collected urine samples from local pregnant women to determine what kind of chemicals they - and their foetus - had been exposed to.

These findings were used to design the cookies for the new study, published today in the journal JNeurosi.

The team fed these cookies to a group of pregnant females rats on a daily basis throughout their gestation and for 10 days after they gave birth.

They then monitored the offspring for the rest of their lives (about a year).

The mothers were not affected at all. And, although previous studies have shown endocrine disrupters to affect puberty of exposed offspring, they saw no difference there; they all passed through that period as expected.

However, once they reached around 90 days old (equivalent to a human in their 20s), the rats that had been exposed to the chemicals were markedly slower in their cognitive abilities.

"It affected their ability to be flexible," Dr Juraska said.

The rats were presented with a maze to work their way through, and occasionally the research team would adjust some parts of it to see how quickly they would realize the difference.

"When the site changed, it took [the chemical-exposed rats] much longer to catch on than rats that haven't been exposed," she said, adding: "I was surprised by the magnitude. I thought there would be an effect, but I was surprised by the magnitude."

Taking a closer look at the neurobiology driving this shift, Dr Juraska, a skilled neuroanatomist, carefully counted each of their neurons and synapses in their pre-frontal cortex, the brain region which affects attention, planning, coordination, and impulse control.

"There was a decrease in both of them in the rats that, all the way back in utero, had been exposed to these chemicals."

Now, Dr Juraska and Dr Schantz are working to determine which phthalates in particular, of the many types we are exposed to, are particularly damaging to the pre-frontal cortex.

They will also be administering these chemicals to rats during puberty to understand whether that has an impact on their neurodevelopment.

In terms of what we can learn from this study, Dr Juraska said there is no point suggesting a ban on these chemicals.

"We are not going to avoid them totally," Dr Juraska conceded. "We have a hard time of banning things that aren't very immediately traumatic. This is a very long term thing."

She did, however, suggest that pregnant women try to boycott anything containing these chemicals for the duration of their pregnancy and nursing period as much as possible.

"My advice would be for pregnant women to avoid plastic, avoid heating thing with plastics and avoid fragrances and air fresheners. Unscented everything is just better, because fragrances often contain these chemicals," Dr Juraska said.

Doing that, she insists, will "minimise your exposure and minimise the exposure for the foetus. It will also minimise the exposure for infants in the house, how much they're breathing in or nursing. It's really an important thing. There's probably no potent time than early development."