Relevance Rating: Medium-Low
- This research is most relevant for woman exposed to high levels of DDT in utero (while in their mother was pregnant with them).
- Participants were pregnant between1959-1967. In the United States, many women who were exposed to DDT during its widespread use in the 1960s are alive today and could be at increased risk for breast cancer. Breast cancers in these woman may also be due to other risk factors and it is not clear from this study if only DDT increased risk or risk was due to other factors or a combination of factors and high levels of DDT in utero.
- Because DDT has been banned in the United States in 1972, this research is not relevant for women born after DDT was banned.
Strength of Science: Medium-Low
- While this study had an appropriate research design, there are some flaws in the interpretation of the results.
- Because the entire study population was from Oakland, California, the results may not apply to people from other regions.
- Researchers cannot definitively conclude that prenatal exposure to DDT was the single factor that accounted for increased risk in the women with breast cancer, or if additional exposure after birth also affected breast cancer risk.
- Nor could researchers conclude that DDT was the only agent that was present prenatally and resulted in increased cancer risk in these women—exposure to other environmental pathogens or pesticides may have also played a role.
- This study only noted whether women were diagnosed with breast cancer by age 52. We do not know at what age women were diagnosed.
- This study only included women from the general population; it is not known how DDT affects people with mutations in BRCA or other genes that predispose people to develop breast cancer.