Triazine herbicide exposure and breast cancer incidence: An ecologic study of Kentucky counties

Michele A. Kettles, Steven R. Browning, Timothy Scott Prince, Sanford W. Horstman

Research output: Contribution to journalArticlepeer-review

138 Scopus citations


The incidence of breast cancer in the United States has steadily increased for the past three decades. Exposure to excess estrogen, in both natural and synthetic forms, has been implicated as a risk factor for the development of this disease. Considerable interest has been focused on organochlorines, such as the triazine herbicides, and their possible role in the initiation or promotion of human breast cancer. To explore this relationship, an ecologic study of Kentucky counties was designed. Exposure to triazines was estimated by use of water contamination data, corn crop production, and pesticide use data. A summary index of triazine herbicide exposure was developed to classify counties into low, medium, or high exposure levels. Data on county breast cancer rates were obtained from the state registry. A Poisson regression analysis was performed, controlling for age, race, age at first live birth, income, and level of education. Results revealed a statistically significant increase in breast cancer risk with medium and high levels of triazine exposure [odds ratio (OR) = 1.14, p < 0.0001 and OR = 1.2, p < 0.0001, respectively]. The results suggest a relationship between exposure to triazine herbicides and increased breast cancer risk, but conclusions concerning causality cannot be drawn, due to the limitations inherent in ecologic study design.

Original languageEnglish
Pages (from-to)1222-1227
Number of pages6
JournalEnvironmental Health Perspectives
Issue number11
StatePublished - 1997


  • Breast cancer
  • Ecologic study
  • Organochlorines
  • Pesticides
  • Triazine herbicides
  • Xenoestrogens

ASJC Scopus subject areas

  • Public Health, Environmental and Occupational Health
  • Health, Toxicology and Mutagenesis


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