Bruce Blumberg, Ph.D. — Effects of Prenatal Obesogen Exposure Echo Down the Generations

From the 2018 One Health One Planet™ symposium — Health Impacts: Chemicals of Concern in the Environment. Find additional resources here:

Effects of Prenatal Obesogen Exposure Echo Down the Generations

Bruce Blumberg, Ph.D. | Professor, Developmental and Cell Biology, School of Biological Sciences, University of California, Irvine

Bruce Blumberg, Ph.D., professor of developmental and cell biology at the School of Biological Sciences, University of California, Irvine, presented recent data pointing to heritable factors beyond diet and exercise that may contribute to the obesity epidemic.

“It’s obvious that diet has something to do with obesity,” Dr. Blumberg said. “But it’s equally obvious that since the rates are continuing to increase, despite unprecedented awareness of the problem, maybe there’s something else going on.”

The worldwide obesity epidemic statistics are alarming, Dr. Blumberg said, citing the latest numbers from the Centers for Disease Control and Prevention that nearly 40 percent of the American population is obese, with African Americans and Hispanics reaching as high as 50 percent, or over that in the case of women. Additionally, health care costs related to obesity have reached the hundreds of billions, he said.

Acknowledging a lack of explanation for the epidemic in the literature — including a 2016 analysis of National Health and Nutrition Examination Study data finding that despite the same caloric input and energy output, the average person’s body mass index was 2.3kg/m2 higher than in 1988 — Dr. Blumberg’s lab investigated prenatal exposure to endocrine-disrupting chemicals as a possible link to obesity — the “obesogen” hypothesis, he said, referring to a term he coined in 2006.

“Calories in, calories out, all by itself is inadequate to explain the rise in BMI. Something else is superimposed on that,” he said. “We know stress, disrupted circadian rhythms, viruses, the kinds of bacteria that live in your intestines — all these have something to do with obesity. We know from a lot of epidemiological studies that prenatal nutrition has something to do with obesity. This prenatal experience has a lifetime effect on health.”

In laboratory mice, Dr. Blumberg and his colleagues showed that in utero exposure of pregnant mice (the F0 generation) to the obesogen chemical tributyltin (TBT), at low levels of parts per billion, had effects through the F3 generation (Chamorro-Garcia et al., 2013).

“What we could show was the animals didn’t weigh any more, but they had more white adipose tissue, the kind we don’t like to see,” he said. “More fat cells, bigger fat cells and fatty livers, and the brown fat didn’t work correctly anymore.”

In a replicated transgenerational study, Dr. Blumberg’s lab showed diet effects on the F4 generation of mice — “in human terms, the great-great-grandchildren of the exposed mom,” he said.

The male F4 descendants displayed resistance to losing fat, even after fasting or changing from a higher-fat to a lower-fat diet. The F4 females did not experience these effects.


We are seeing unprecedented changes in the earth’s environmental and physical processes. Climate change, air pollution, reduced availability of clean water, and persistent toxic chemicals threaten human, animal, and environmental health and well-being.

To build a shared interdisciplinary vision of “health” and serve as a catalyst for positive change, Phipps Conservatory brings together leaders to explore global and local environmental issues and their effects on human, animal and environmental health through the One Health Initiative. One Health is a movement that is forging a new level of collaboration among physicians, veterinarians, scientific-health and environmentally-related disciplines. Thought leaders from disparate fields promote strategies to expand interdisciplinary understanding and communication in all aspects of healthcare for humans, animals and the environment.