Plastic linked to higher rates of autism

Broadcast date: a week August 5, 2022

Stream/ Download this clip as an MP3 file

Scientists, doctors and activists have called for more studies on autism that examine both genes and toxic chemicals. (Photo: The Focal Project, Flickr, CC BY NC 2.0)

The CDC reports that 1 in 44 children currently has an autism spectrum disorder and that number is increasing annually. In a commentary and study in the Journal of Pediatrics, scientists and clinicians urged that autism research should take into account genetic interactions with synthetic compounds, including a class of hormone-disrupting chemicals called phthalates. Phthalates Are Common in Plastic Dr. Irva Hertz Piccito, Director of the Center for Environmental Health Sciences at UC Davis and co-author of this study joins host Steve Corwood to talk about the interaction between chemicals, genes, folic acid, and autism. .


CURWOOD: From PRX, Jennifer, and Ted Stanley Studios at the University of Massachusetts Boston, this is a great copy of Living on Earth.
I’m Steve Corwood.
The number of children diagnosed with autism spectrum disorder in the United States is growing at an astonishing rate, rising by nearly seven percent over recent years, according to the Centers for Disease Control.
Scientists point to a small number of studies linking plastic to an increase in autism, a disorder often characterized by poor social and communication skills, as well as learning problems that require special help.
Phthalates are a group of chemicals used to make plastics more flexible and are found in a variety of products from shampoo to food packaging.
Phthalates have already been linked to many diseases, including obesity, heart disease, low IQ, and birth defects.
And now half a dozen studies link exposure to phthalates with disrupting the way our genes tell our bodies folic acid, a compound for proper brain development.
The CDC’s announcement follows a commentary and study in the Journal of Pediatrics, in which scientists and clinicians urged that a study of autism should take into account genetic interactions with toxic chemicals.
The good news is that even with the spread of plastics, there is a fairly simple and inexpensive public health solution that can curb the rise in autism cases.
Supplemental folic acid for women.
For more information we now turn to Dr. Irva Hertz Piccito, director of the Center for Environmental Health Sciences at the University of California Davis, and co-author of this study.
Welcome back to Living on Earth, Irva!

Hertz Pekoto: Thanks for having me.

Corwood: So, as I understand it, the CDC has found a 7% increase in autism diagnoses among 8-year-olds over the past two years. Oh boy, that’s a pretty high rate. How worried is that?

HERTZ-PICCIOTTO: Sure, it’s concerning. I mean the number of children who need special education, special facilities may have all kinds of difficulties in school, but also just in everyday life, it’s remarkably high. Because they often require a lot of special attention, and special adaptations to their disabilities, they have economic consequences, and are sure to have a lot of financial, social, and emotional consequences for families. So yes, I agree that it is very concerning.

Folic acid is necessary for the overall formation of the brain and the development and brain function of fetuses during pregnancy. Studies show that it plays an important role in preventing the development of autism when it is abundant in early pregnancy. (Photo: Tatiana, Flickr, CC BY 2.0)

Corwood: Researchers have now known about autism and some sort of connection to genetics since the 1970s. But now we’re learning through studies like yours that chemicals like plasticizers and phthalates may have a role to play when it comes to neural development. So, in your view, what is the relationship, if any, between autism, genetics, gene expression, and exposure to chemicals?

Hertz-Picotto: Well, there’s a lot of literature on genetics. So, we really have a good sense of the many genetic factors that might regulate how the body metabolizes, you know, the chemicals we’re exposed to, and how certain kinds of genes that regulate brain development might be affected. Therefore, there is a lot of potential for allergies during the prenatal period in particular and this is not the period of time when exposure to endocrine-disrupting chemicals appears to have strong effects on behavior, memory, cognitive abilities and also mood problems such as depression and anxiety, it seems that all of these Particularly affected by phthalates. I will only cite them because there is a growing literature on these compounds, phthalates.

Corwood: One of the most interesting parts of your research paper, which is actually kind of a meta-study looking at a number of different studies, looking at autism, is the effect of folic acid, folate, this nutrient that’s in everything from kale. To lentils for all sorts of things. Well, tell me, what is the effect of people getting good amounts of folic acid in their diets?

HERTZ-PICCIOTTO: Some of our studies and studies by others have shown that folic acid is really important in autism and that mothers who didn’t have enough folic acid in the very early part of pregnancy, and I mean, like the first month, were more likely to have a child who had autism , when they have reached the age at which autism can be diagnosed, let’s say age 2, 3, 4, 5 and so on. Therefore, it appears that folic acid is important for more than just the overall make-up of the brain but also for other aspects of brain function related to communication, social interactions, etc.

Corwood: To what extent does adequate folic acid mitigate the effects of chemicals like phthalates that are implicated in this, dare I say, epidemic?

HERTZ-PICCIOTTO: Well, interestingly, what our studies and many other researchers have found is that some mothers have a much greater need for folic acid and that’s because their genes don’t turn into folic acid very quickly and as a result, they are at a much higher risk of having a child with autism . Therefore, it is the combination of a low intake of folic acid and certain genetic variants that increases the need for more folic acid and thus increases the risk of their child developing autism if they do not develop it. And moms who get enough folic acid and have the genes that are really helpful in moving folic acid into folic acid and then into its methylated state, which makes it really effective, those are the moms who are least likely to have a child with autism. And if she has the good genes as well as her child, there is an even greater benefit with a 70% reduction in the risk of autism as well as taking folic acid.

Corwood: Because brain development happens very early in pregnancy, really only during the first few weeks, that’s exposure to folic acid deficiency. To what extent should women of childbearing age make sure that they always have a decent level of folic acid in their diets for the chance that they will become pregnant at some point and may not understand that they are pregnant during this time that this is an important development taking place?

Hertz Picoto: That’s absolutely right. Half of the pregnancies are unplanned, you know, we’re not going to change people’s behavior, to have everyone plan their pregnancies. So being prepared by taking a folic acid supplement, or prenatal supplement, is likely to be beneficial everywhere. This can be a very easy public health intervention to strongly encourage women to do so.

According to a 2018 CDC report, one in forty-four children was identified as having an autism spectrum disorder compared to 1/54 in 2016 (Photo: Wall Boat, Flickr, Public Domain)

Corwood: Now, this research that you’re involved in is limited in scope in the public health community. I think it’s less than a dozen studies looking more closely at environmental toxicity, genetics and autism. why is that?

Hertz-Piqueto: Well, I think scientists kind of work in silos, geneticists are interested in genetics and ecologists are very busy, you know, studying the environment. It’s shocking to me that research into the causes of autism is about 20 years old, you know, mature at this point in time. I mean, even in the ’90s, there were genetic studies, I’d say environmental studies really picked up in the mid-late 2000s. There’s a lot of work going on separately but combining the two requires really special circumstances, you have to get bigger studies, bigger sample sizes, but the environment can take a lot to be able to measure plus it changes, you know, the DNA code is constant throughout your life, While the environment changes day by day or hour by hour sometimes. Thus, it is even more difficult and I think having minds coming from these two fields combining their intelligence and finding creative solutions to these challenges would really push this literature forward.

Corwood: Dr. Irva Hertz Piccito is director of the Center for Environmental Health Sciences at the University of California, Davis. Thank you very much for your time with us today.

Hertz Picoto: Thank you very much for having me.


Read the commentary in the Journal of Pediatrics entitled: Consideration of Toxic Chemicals in Autism Etiology.

Learn more about CDC data and statistics on Autism Spectrum Disorder

Center for Disease Control | “Prevalence and Characteristics of Autism Spectrum Disorder among 8-Year-Old Children – Autism and Developmental Disabilities Monitoring Network, 11 sites, United States, 2018”

Learn more about Dr. Irva Hertz-Picciotto

Leave a Comment