Biased General Electric PCB Cancer Study

General Electric promotes junk science. The GE cancer study was seriously flawed and biased research.

The GE Cancer Study Was Flawed

The Fox Valley paper industries hailed a major study released in 1999 by General Electric (GE) of more than 7,000 of the company's workers because it supposedly shows that PCBs do not cause cancer. However, the biased research was seriously flawed and its results misrepresented.

The study was based primarily on inhaled PCBs. Inhaled PCBs or PCBs absorbed through the skin tend to be the lighter weight types of PCBs (out of 209 possible) with fewer chlorine atoms attached --- not the highly-chlorinated versions more strongly associated with cancer. Airborne PCBs are more likely to produce nervous system damage or other health problems, with cancer a lesser risk, so the researchers were looking for the wrong types of health problems. This is important because the more carcinogenic forms of PCBs tend to accumulate in fish, ducks and other animal-based foods selectively, while the lighter PCBs go airborne. Those who eat fish from the Fox River and Green Bay need a cancer study which specifically examines fish-eaters' cancer rates. (We haven't found a single study of this type, which is disturbing after all these years.)

The study actually showed some increases in 3 of the 6 types of cancer investigated (according to the Agency for Toxic Substances and Disease Registry, see below), but the company downplayed these results.

GE paid a chemical-industry-funded research group to hire private detectives to find every GE employee who worked at or near the PCB plants in Hudson Falls and Fort Edward in New York state, which creates a potential selection bias affecting which people they chose to find [ie: those without cancer?]

(Source: Hudson Sloop Clearwater )

Many of the people in the study worked at GE less than a year. The researchers only required a work history at GE of at least 90 days.

The study did not account for the lag time (latency) which can occur between the time of PCB exposure and the development of cancer. The lag time can often be 20 or 30 years after exposure.

The study included thousands of people who never came into physical contact with PCBs. If every worker who did come in contact with PCBs died of cancer, the mortality would not have been "statistically significant" because their numbers would have been swamped-out by the large number of non-exposed people in the study.

(Source: Hudson Sloop Clearwater )

The study did not look at the incidence of cancer, just mortality. Every single former GE employee could have been battling cancer for twenty years with no impact on this GE-funded study, because GE didn’t count cancer sufferers or survivors, only the dead.

The study did not look at long-term health effects in workers' children, which may be significant.

Scientists Critique the GE Study

Scientists are highly critical of the "no cancer from PCB" claims being made as a result of the GE study. For example:

"Most of the workers didn't work in areas where PCBs were used, and those who did were there on average only a couple of years," said James Cogliano, PhD, Chief of the Quantitative Risk Methods Group for the EPA. "Some classified as exposed had PCB blood levels in the low range of background levels in the general public. Others were classified as highly exposed if they worked with PCBs for only a short time. Those kinds of things can dilute results, and create enormous potential for uncertainty."

Michael Thun, MD, Vice President of Epidemiology and Surveillance Research for the American Cancer Society, said, "The bad news is PCB exposures were not well characterized, the study was too small to detect small risks for uncommon cancers, and the results may not be relevant to PCB exposure through food. Also there was a borderline association with colorectal cancer in women. That needs a closer look."

Officials from the Agency for Toxic Substances and Disease Registry say the study does not support the company's claims that PCBs do not hurt people because it suffers from exposure misclassification (by including individuals who worked at the plants but had little to no exposure to PCBs), failure to account for the latency period between exposure and appearance of cancer, and other biases. PCB levels were actually measured in only 200 of the over 7,000 people in the study. "Nevertheless, the study did find excesses in three of the six cancers of interest," the ATSDR officials noted in a published letter criticizing the study. (Source: Clean-up GE)

"It's noteworthy that the GE-funded study is the only one of the major occupational PCB exposure studies that did not find some statistically significant elevation of incidence of cancer," says Dr. David Carpenter of the Albany School of Public Health. "Every international group of experts that has been asked to look at the issue has concluded that they are proven to cause cancer in animals and are probable carcinogens in humans." Carpenter adds that there can be no absolute proof that PCBs (or any other chemical for that matter) cause cancer because there's no way to control for other exposures. "There's just no doubt that PCBs are carcinogenic in the minds of any independent scientist. It's only people with close ties to industries that have conflicts of interest that would make such preposterous claims. It's very akin to the smoking, cancer and tobacco industry story. To have a corporation like General Electric deny that animal research, including research done by their own laboratories proving PCBs cause cancer in rats, is relevant to whether PCBs cause cancer in humans is ludicrous. Our whole system of study of disease is based on animal research. Unfortunately the public has become confused because of the message that GE and other industries have put out." (Source: Clean-up GE) For more information, see PCBs and Cancer Effects

Political Use of Junk Science

GE is facing billions of dollars in clean-up costs at multiple PCB-contaminated Superfund sites around the country, such as the Hudson and Housatonic Rivers in the Northeast. They may also face numerous private lawsuits over PCB health damages in former workers and customers. GE has a vested interest in whether PCBs cause cancer. (See links to GE's actions on the Hudson and Housatonic Rivers.)

The GE cancer study had a purpose --- junk science: "They want to cause public confusion, and make the argument appear to seem scientifically complicated, because they know that oftentimes the public will tune out as soon as it gets complicated," says Judith Enck, policy advisor to New York Attorney General Elliott Spitzer. (Source: Clean-up GE)

The bad science is also used to wear down third party support for the cleanup. The claim that PCB's don't cause cancer was brought out in April when GE officials led by NBC president and GE vice chairman Robert Wright met privately with New York City Council members to lobby against a council bill endorsing the dredging project. GE's Albany lobbyist, James McMahon sat in on the meeting, along with his brother Thomas, the City Council's former finance director and a lobbyist with the Chamber of Commerce. (Source: Clean-up GE)

Links to More GE Information

For more discussion of the GE study, see Appleton Post Crescent article from 3/11/99, and an 9/25/00 article in the Poughkeepsie Journal in New York.

The Hudson Clearwater Sloop also chronicles inaccuracies in other GE claims.

A U.S. EPA response to a GE letter on the Housatonic River gives more examples of GE’s inaccurate claims.

Journal Abstract of the GE Cancer Study

Renate D. Kimbrough, MD, Martha L. Doemland, PhD, Maurice E. LeVois, PhD. Mortality in Male and Female Capacitor Workers Exposed to Polychlorinated Biphenyls. JOEM 41:3 (March 1999), pp 161-171

"A mortality study was conducted in workers with at least 90 days' exposure to polychlorinated biphenyls (PCBs) between 1946 and 1977. Vital status was established for 98.7% of the 7075 workers studied. In hourly male workers, the mortality from all cancers was significantly below expected (standardized mortality ratio [SMR] = 81; 95% confidence interval [CI], = 68 to 97) and comparable to expected (SMR = 110; 95% CI, 93 to 129) in hourly female workers. No significant elevations in mortality for any site-specific cause were found in the hourly cohort. All-cancer mortality was significantly below expected in salaried males (SMR = 69; 95% CI, 52 to 90) and comparable to expected in salaried females (SMR = 75; 95% CI, 45 to 118). No significant elevations were seen in the most highly exposed workers, nor did SMRs increase with length of cumulative employment and latency. None of the previously reported specific excesses in cancer mortality were seen. This is the largest cohort of male and female workers exposed to PCBs. The lack of any significant elevations in the site-specific cancer mortality of the production workers adds important information about human health effects of PCBs."