Historical News Releases & Statements

September 6, 2008

Analysis of Ecuador Data Reveals No Increased Cancer Levels in Oil Region

Peer-Reviewed Study Debunks Claims by Plaintiffs in Lawsuit Against Chevron

Quito, Ecuador, Sept. 6, 2008 - People in Ecuador's oil-producing region do not experience higher rates of cancer than residents of non-oil producing areas of the Andean country, contrary claims by plaintiff's lawyers in a lawsuit against Chevron, according to a peer-reviewed study of government mortality data.

"Our analysis of national mortality data of the Amazon Region in Ecuador does not provide evidence for an excess cancer risk in regions of the Amazon with long-term oil production," concludes the study published in the respected International Archives of Occupational and Environmental Health.

The study, "Cancer Mortality and Oil Production in the Amazon Region of Ecuador, 1990-2005," was funded by Chevron to evaluate, using solid scientific analysis, the legitimacy of the plaintiffs' lawyers' allegations. It is the first known analysis of national mortality data to investigate cancer risk and oil extraction activities in the Amazon region of Ecuador.

The study was conducted by a team led by Dr. Michael Kelsh, adjunct professor of epidemiology at the University of California at Los Angeles and principal scientist at consulting firm Exponent, who has extensive experience working on environmental health issues in Latin America and the U.S. The team also included Dr. Libby M. Morimoto, a senior scientist at Exponent's Health Sciences Center for Epidemiology, Biostatistics, and Computational Biology, and Edmund C. Lau, a senior managing scientist at Exponent.

The authors analyzed cancer mortality rates in Ecuador using official government statistics from the Instituto Nacional del Estadistica y Censos (INEC) as well as health claims made in environmental studies promoted by plaintiffs in the case. In analyzing the plaintiffs' claims, Kelsh, Morimoto and Lau observed:

"The results of this mortality study contradict those observed in a series of ecologic studies by Hurtig and San Sebastian (Hurtig and San Sebastian 2004, 2002; San Sebastian and Hurtig 2004)…. The San Sebastian incidence studies relied on the 1990 data to estimate population at the midpoint of their study period (1992) and assumed this average population size across the duration of the study period. This method likely underestimated the population of the exposed regions, which experienced more rapid population growth than unexposed regions (see Table 3). This underestimation of the population at risk in exposed regions would artificially inflate cancer rates in these areas and may explain their observation of elevated cancer risks (Tong 2000)."

In their analysis of the mortality data, the authors report:

"In the current analysis, mortality in cantons (municipalities) with long-term oil extraction activities were similar, or lower, compared to those without such activities for overall mortality, overall cancer, circulatory disease, infectious disease, and respiratory diseases, and for many site-specific cancers… In analyses using regional oil well density as a surrogate for exposure, there were no statistically significant elevations in cancer rates in cantons with a high density of oil wells, relative to those with a low or zero density."

Chevron officials said the study by Kelsh, Morimoto and Lau strongly supports the company's case before the Ecuador's courts and shows that the plaintiffs' claims as well as those made in a report by a so-called "expert" appointed by the court are not supported by serious science and don't withstand rigorous analysis of the available data.

"These findings are significant for three reasons," said Dr. Ken Satin, Staff Epidemiologist for Chevron Energy Technology Company. "First, this study was based on the most complete set of available health outcome data. Second, this study reviews and highlights the scientific limitations in the San Sebastian ecological reports promoted by the plaintiffs'. Such limitations render the findings and conclusions of those reports unreliable and inaccurate. Finally, and most significantly, this study is a compelling rebuttal to the assertions made by mining geologist Richard Cabrera in his much-criticized assessment submitted to the Superior Court. While the study by Kelsh, Morimoto and Lau uses a sound scientific approach to analyze available public data, Mr. Cabrera's health assessment is so deficient with respect to design, data collection, analysis, and interpretation that its findings offer no scientifically defensible insight into the health of people living in the Amazon region of Ecuador."

The conclusions of the study are consistent with the findings of the Ecuadorian Facultad Latinoamericana de Ciencias Sociales (FLACSO), which found that known health conditions of people in the region could not be directly attributed to oil production activities.


A reprint of the complete study published in the International Archives of Occupational and Environmental Health can be found at http://www.texaco.com/sitelets/ecuador/en/responsetoclaims/default.aspx.

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