Can Grandma's Toxic Exposure Affect Child's Risk of Autism?

June 19, 2012

This week’s “Got Questions?” answer comes from Alycia Halladay, Ph.D., Autism Speaks director of research for environmental sciences.

My mother was exposed to a potentially toxic chemical during her pregnancy. How does that affect the risk of autism in my children and my grandchildren?

We have received many questions about whether exposure to a potentially toxic chemical during pregnancy can affect the risk of autism not just for the woman’s child but also for her grandchildren or even future generations. Scientists call this a transgenerational effect. It’s a hot area of research, as well as a concern for families.

We are beginning to scratch the surface on transgenerational effects. Recently three animal studies examined the effects of environmental exposures on several generations. The latest study, funded in part by Autism Speaks, investigated the effects of exposure to bisphenol A (BPA), which is found in many plastics. The two other papers looked at exposure to other environmental chemicals. One concerned a fungicide. The other concerned a jet-fuel chemical that has become widespread in our environment.

In all three studies, researchers exposed pregnant mice or rats to the chemicals and then tested their offspring, their “grand” offspring and their “great-grand” offspring. Specifically, they looked for intergenerational changes in behavior, anatomy and biology. All found such changes in all three generations.

We don’t yet understand the mechanisms behind these generation-spanning effects. However, researchers suspect that certain environmental exposures can affect sperm- and egg-producing tissues in developing embryos or fetuses. This, in turn, can affect future generations by altering natural chemicals that surround DNA and modify how genes are expressed.  If future eggs and sperm are affected, the changes can pass down through generations.

These results are intriguing. However, it’s too early to draw conclusions. For example, in the BPA study, the mother’s exposure to BPA caused her offspring to have decreased social skills. However, the researchers saw greater socializing in her grand-offspring and great grand-offspring. We don’t know why.

The findings of transgenerational effects could have broad implications and may be important in understanding a number of disorders including autism. However, the research is preliminary, and we don’t yet know how this translates to people and their exposures to these chemicals. These important questions into gene-environment interactions deserve scientific research to find the answers.

Autism Speaks continues to fund a number of studies on the environmental influences that may affect autism risk in future children. You can explore these and other studies using our Grant Search.

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