Public Health Institute

"The beauty of the CHDS is that because the study has continued for over 50 years, we don't have to wait for time to pass to know whether exposure to a particular chemical at a vulnerable time in early life increases the risk of breast cancer."

– Barbara Cohn,
CHDS Director

Because of the CHDS, doctors know:

  • Which medicines pregnant women can take safely to reduce nausea and which medications for mental health disorders and fluid retention may be harmful or require more testing
  • Smoking during pregnancy and exposure to second-hand smoke can be harmful to an unborn child
  • How to assess normal gains in weight and height for children
  • Why some men and women are more at risk for infertility
  • Protective factors for aging men and women that may help prevent cancer, heart disease, asthma and diabetes

Child Health and Development Studies (CHDS)

Researchers at the Child Health and Development Studies (CHDS) are embarking on what is believed to be the first human "womb to breast cancer" study, testing whether a connection exists between exposure to environmental chemicals at key points in breast development and breast cancer later in life.

The five-year Environmental Causes of Breast Cancer Across Generations Study will investigate differences in environmental exposures by race, ethnicity and social class to better understand disparities in breast cancer occurrence and deaths. The study, nicknamed the "Three Generations Study" and "3Gs," is funded by the California Breast Cancer Research Program (CBCRP), the nation's largest state-funded research effort, and is the biggest of its "special research initiatives."

"Breast cancer incidence has been increasing over the past several decades and although there are now genes we know about that contribute to breast cancer, they contribute in only a small percentage of cases," said CBCRP director Mhel Kavanaugh-Lynch. "In 30 to 50 percent of the cases, we have no idea why a woman gets the disease. It's clear we are missing something. Whether it is environmental causes is an area of intense public interest, but this has had relatively little scientific interest."

Studies on the role environmental toxins play in the development of breast cancer have either focused on animals or emphasized testing for recent exposures in older women diagnosed with the disease rather than on periods early in life when the breast is most vulnerable, such as prenatally, in infancy and in puberty.

The 3Gs will draw on the remarkable resource of the CHDS, an ongoing longitudinal study started more than 50 years ago to better understand factors influencing healthy pregnancy and child development. About 15,000 pregnant Kaiser Foundation Health Plan members in Oakland enrolled in the study from 1959 to 1967, providing blood samples and extensive medical and personal histories. Numerous follow-up studies of these mothers have linked events and exposures during pregnancy to health, disease and reproductive problems to themselves and their offspring. The Berkeley-based CHDS is a project of the Public Health Institute.

CHDS Kids - 1960's

UNCOVERING CANCER RISKS BEFORE BIRTH

Three Generations Study researchers will examine two chemical compounds -- PCBs used primarily in insulation of electrical equipment and the insecticide DDT - that were widely used in the 1950s and 1960s. The women participated in the CHDS during this period and thus were exposed to these chemicals.

"The beauty of the CHDS is that because the study has continued for over 50 years, we don't have to wait for time to pass to know whether exposure to a particular chemical at a vulnerable time in early life increases the risk of breast cancer," said CHDS director Barbara Cohn.

The 3Gs study will try to uncover why some of the CHDS daughters, now in their forties and fifties, have developed breast cancer by testing their mothers' preserved blood taken during and just after pregnancy for both chemical compounds and the chemicals they break down into.

But the study will go much further, altogether enrolling more than 4,000 daughters, including a group of daughter-granddaughter sets -- thus taking in three generations -- to expand follow-up and understand whether increased risk for breast cancer continues in subsequent generations. The study will also enable future CHDS researchers to identify whether other environmental chemicals these generations are exposed to today lead to the onset of breast cancer and other illnesses much later. Blood, urine and salvia samples from the second and third generations will be archived for the future studies.

"Ultimately we hope that we'll find some answers to what may increase a woman's chances of breast cancer and. more importantly, point to what we can do to decrease breast cancer in our current generation and our daughters' generation," said Kavanaugh-Lynch.

The 3Gs builds on a study by Cohn and her colleagues in 2007, which found CHDS mothers exposed to DDT before the age of 14 were five times as likely to develop breast cancer if they also had high levels of DDT in their blood during pregnancy.

The California Breast Cancer Research Program is funded by the voluntary check-off on income tax forms, the tobacco tax and contributions.

To learn more about CHDS, visit www.chdstudies.org