When Rachel Carson�s �Silent Spring� first sounded the alarm on DDT and
its devastating effects on birds and fish, our understanding of how this
pesticide affected humans was just beginning. Chemicals can take years to
reveal their insidious power, and so for decades, scientists have been
piecing together � study by study � the reasons why DDT still haunts us
today.

First it was breast cancer in women who were exposed to this hormone-
disrupting chemical in the 1950s and �60s. Then their daughters, who had
been exposed in the womb. Researchers over the years have also linked DDT
exposure to obesity, birth defects, reduced fertility and testicular
cancer in sons.

Now, a team of toxicologists, molecular biologists and epidemiologists at
UC Davis and the Public Health Institute in Oakland have confirmed for the
first time that granddaughters of women who were exposed to DDT during
pregnancy also suffer from significant health threats: Higher rates of
obesity and menstrual periods that start before age 11.

Both factors, scientists say, may put these young women at greater risk of
breast cancer � as well as high blood pressure, diabetes and other
diseases.

�This is further evidence that not only is a pregnant woman and her baby
vulnerable to the chemicals that she�s exposed to � but so is her future
grandchild,� said Barbara Cohn, director of the Public Health Institute�s
Child Health and Development Studies, a multigenerational research project
in California that has followed more than 15,000 pregnant women and their
families since 1959.

�This is something that people had always thought was possible,� she said,
�but there had never been a human study to support the existence of that
link.�

The findings come at a time of renewed public interest in DDT, a problem
that had been largely tucked into a fading chapter of history. Concerns
have intensified since The Times reported last fall that the nation�s
largest manufacturer of DDT once dumped as many as half a million barrels
of its waste into the deep ocean.

The pesticide, now banned, is so stable it continues to poison the
environment and move up the food chain. Significant amounts of DDT-related
compounds are still accumulating in Southern California dolphins, and a
recent study linked the presence of these persistent chemicals to an
aggressive cancer in sea lions.

As for humans, �there�s a clear line you can track of what�s happening,�
said Linda Birnbaum, who, as the former director of the National Institute
of Environmental Health Sciences and the National Toxicology Program, has
been following these multigenerational studies with great interest.

�A lot of people want to think that the problems with DDT have gone away,
because Congress banned it in 1972. Well, they haven�t,� said Birnbaum,
who is now a scholar in residence at Duke University. �By the time the
daughters got pregnant with the granddaughters, that was long after DDT
had been banned � and yet they were carrying within them the seeds of
these problems.�

::

More than 60 years ago, in the heyday of DDT, a team of scientists had the
foresight to start collecting blood samples from more than 15,000 pregnant
women at the Kaiser Permanente hospital in Oakland. At every trimester and
also shortly after birth, each woman provided a sample that was studied
and carefully archived.

Researchers tested the blood for DDT, dichlorodiphenyltrichloroethane, and
continued to follow up on health assessments. They kept in touch with the
women�s daughters, who had been exposed to DDT in the womb, and then with
their granddaughters.

They found, after years of research, that women heavily exposed to DDT
during childhood are five times as likely to develop breast cancer, and
that a mother�s DDT exposure during pregnancy, or immediately after birth,
is linked to an increased risk of breast cancer for their daughter. Their
daughters are also more likely to experience delays in getting pregnant.

In this most recent study, published Wednesday in the journal Cancer
Epidemiology, Biomarkers & Prevention, the research team found that the
risk of obesity in the granddaughters � who are now in their 20s and 30s �
was two to three times greater than women whose grandmothers had little
DDT in their blood during pregnancy. These granddaughters were also twice
as likely to have much earlier menstrual periods � another indicator of
increased health risks later in life.

This persistent, generational exposure is likely related to the
reproductive system, Cohn said. Since a female is born with all her eggs,
a granddaughter is technically also exposed to DDT if her mother was
exposed in the womb.

�Even though we banned that stuff more than 40 years ago, people now
walking the Earth � the granddaughters of those who were pregnant � were
exposed,� Cohn said. She wonders if the increasing rates of childhood
cancer, diabetes and other health problems affecting young people today
are also somehow connected to these chemicals of the past. �It�s the full
meaning of what a �forever chemical� is � in some ways, that makes every
chemical potentially �forever� if it has the potential to do this.�

Bruce Blumberg, a professor of developmental and cell biology at UC
Irvine, still remembers the trucks that used to spray massive amounts of
DDT in farms and neighborhoods. At the supermarket where he worked as a
kid, foggers would be brought inside at the end of each day.

�The whole market would be full of a fog of DDT,� said Blumberg, who also
teaches pharmaceutical sciences. �The industry would want you to believe
that chemicals have no effect, because the doses are too low and there�s
just no effects and it�s all crazy alarmists.�

Blumberg now specializes in studying how chemicals in the environment can
affect our genes and predispose people to obesity, which affects about 42%
of Americans today. He conducts lab experiments on mice to answer the many
questions that scientists have been unable to test on humans.

That�s why the multigenerational Bay Area study, which he�s not affiliated
with, is so important, he said. It provides much-needed human
observational data that are incredibly hard to come by � perhaps even
harder to maintain.

�If we�re lucky, that cohort [of Bay Area women] will continue through
four, five, six generations,� he said, �and we�ll really learn something
about the effects of what happened in the past on the future.�

::

Akilah Shahid said she was shocked, yet fascinated, to learn that she was
in the third generation of a major study on how chemicals in the
environment could be affecting women.

A biology major at Mills College, Shahid said it all clicked for her for
when she dug into the research. Her family has been no stranger to health
problems. Her grandmother alone has fought cancer three times.

�I feel like, for a while, cancer just came out of nowhere,� she said.
�You don�t know who�s going to get it, and now we have a reason why.�

Shahid, now 30, exercises a lot. She tries to eat well. It empowers her to
know that her weight isn�t completely her fault � and that there�s only so
much within her control.

DDT isn�t allowed anymore, but she can�t help but wonder about all the
other chemicals still prevalent today � bisphenol A (BPA), per-and
polyfluoroalkyl substances (PFAS) and other manufactured compounds that
don�t seem to ever go away. She avoids plastic water bottles and tries to
be mindful of how her choices and actions right now could expose her
future grandchildren to some unknown disease.

�How many times have we talked about climate change and things that we
need to do better for our children and grandchildren? This is more proof
that hello, what we do today is going to affect people way forward,� she
said.

�I hope this is a wake-up call for a lot of people, because we�re talking
about saving the environment again, today, for our future generations.�

https://www.latimes.com/environment/story/2021-04-14/toxic-legacy-of-ddt-
can-harm-granddaughters-of-women-exposed