References
Q1. What is acrylonitrile? What is it used for?
A. Acrylonitrile is an "intermediate" chemical used by manufacturers to create other products. It is used to make acrylic fibers for clothing, blankets and carpeting; durable plastics for computers, appliance and VCR housings, sports equipment and auto components; and nitrile rubber for hoses at gasoline service stations and under your car's hood.
Q2. How many AN plants in the world? How much is produced?
A. Approximately 80 plants in 22 countries produce about 10 billion pounds of acrylonitrile each year.
Q3. Is AN toxic? Can overexposure kill you?
A. AN is a volatile hazardous chemical and is regulated as such throughout most of the world. If inhaled at high concentrations, it can produce serious short-term toxicity, including loss of consciousness or death. When appropriate safety precautions are in place to limit exposure no appreciable danger exists.
Q4. Can exposure to acrylonitrile in the workplace cause cancer?
A. In 1997-98, four major health studies involving 33,624 acrylonitrile workers throughout the world came to the conclusion that exposure to AN does not increase cancer risk. One major study by the National Cancer Institute (NCI) followed 25,640 workers employed at U.S. plants that produced AN or used it to make other products from the 1950's through 1983. The study tracked workers' health records through 1989, and found no evidence of significant increase in risk for cancer death or any other cause of death due to exposure to AN.
Q5. What is the NCI?
A. The NCI coordinates the U.S. government's cancer research program. NCI is the largest of the 17 biomedical research institutes and centers at the National Institutes of Health in Washington, DC. NCI website: www.nci.nih.com
Q6. Why did NCI do the study?
A. Early laboratory studies showed evidence of increased cancers of the brain and ear duct in rats. In the early 1980's, the NCI agreed to a request by acrylonitrile manufacturers to conduct a definitive, high quality health study of workers exposed to acrylonitrile. The 10-year, $20 million study examined 25,460 workers employed in eight U.S. plants from the 1950's through 1983.
Q7. Who led the study for NCI? How can I get a copy of the study results?
A. Dr. Aaron Blair, Occupational Epidemiology Branch, National Institutes of Health, led the study for NCI.
Q8. Did industry pay for the study? What was industry's involvement?
A. The NCI study was funded by the National Cancer Institute, not by industry. The AN industry co-operated by providing exposure data and access to company facilities and employee records. The study was solely conducted by the NCI.
Q9. What were the results of the NCI study?
A. The study found no evidence of an overall increased risk for cancer death or any other cause of death. No increase was observed for leukemia, lymphoma, or cancers of the stomach, brain, breast or prostate, which were types of cancer previously associated with animal studies. A slightly increased risk for lung cancer was seen among workers experiencing the highest levels of AN exposure. However, the lung cancer excess was limited to a single plant and thus may be the result of other exposures. The NCI concluded that the study results "do not provide strong or consistent evidence for a causal association" between acrylonitrile and lung cancer. The NCI plans to continue its study of lung cancer in the future by identifying and analyzing cancer deaths occurring after 1989.
Q10. Do you agree with the findings?
Yes. Intense reviews of the NCI study by independent health professionals and industry experts have determined the conclusions to be valid. Following the completion of the NCI study – as well as three other AN health studies in the UK, Netherlands and U.S. – a meeting was held in Oxford, England in Aug., 1997, to assess overall health data for AN worker . In attendance were the principal investigators for the major studies; academics with special interest in occupational medicine; and representatives of regulatory bodies, industry groups and labor unions. Based on the data presented, it was agreed by those in attendance that there is insufficient evidence to conclude that exposure to acrylonitrile is associated with an increase in human cancer. In a review of the papers presented at the conference, Drs. David Coggin Environmental Epidemiology, Southampton General Hospital, and Philip Cole of the University of Alabama, concluded: "Thus despite its carcinogenicity in animals, there is little evidence to suggest that (acrylonitrile) causes cancer in humans."
Q11. Will the NCI study reduce or eliminate lawsuits by workers/local residents?
The NCI findings that AN is not a cancer risk will definitely increase the burden of proof for plaintiffs attempting to prove AN caused any health problems.
Q12. Why did NCI only follow workers through 1989?
A. To begin compiling data for study the NCI had to select a cutoff year. NCI has indicated that follow-up studies of workers' records beyond 1989 will be performed in the future.
Q13. What would have happened if the NCI study concluded that AN causes cancer in humans?
A. We prefer not to speculate about something that obviously did not happen.
Q14. What does the study mean to people in neighboring communities?
A. Since workers experience a potentially higher level of AN exposure than local residents, we can logically conclude that the risk of cancer in local residents is no higher than the normal worker population. Communities can breathe easier knowing AN emissions at current levels are not a cancer risk to workers.
Q15. What is IARC?
A. The International Agency for Research on Cancer (IARC) is part of the World Health Organization. IARC's mission is to coordinate and conduct research on the causes and mechanisms of cancer, and to develop scientific strategies for cancer control. The IARC system for rating chemicals for carcinogenicity is used in many countries to determine how chemicals should be regulated.
Q16. What is the IARC rating for AN? What does it mean?
The IARC lowered its rating for AN from 2A (probable carcinogen) to 2B (possible) human carcinogen. According to IARC, this category is used when there is inadequate evidence of cancer in humans but there is sufficient evidence of cancer in experimental animals. Inadequate evidence for cancer in humans indicates that work studies found no consistent increased cancer risk across studies. Please contact IARC for more information.
Q17. Why did IARC lower the rating? Did the NCI study affect it?
A. There is no doubt the NCI study affected the IARC rating for AN. In fact, IARC had been planning to review the AN rating at this time, anyway, so the NCI study was very timely. Also, in 1997-98, four major health studies (including the NCI study) involving 33,624 AN workers worldwide came to a similar conclusion that AN does not increase cancer risk. This type of solid research is hard to refute.
Q18. Please explain the IARC rating system.
A. Basically, IARC evaluates potentially hazardous substances using the following ratings based on the existing body of research:
- Group 1: Cancerous to humans
- Group 2A: Probably carcinogenic to humans
- Group 2B: Possibly carcinogenic to humans
- Group 3: Unclassifiable as to carcinogenicity to humans
- Group 4: Probably not carcinogenic to humans
Agencies throughout the world use the IARC ratings as a guide to set regulations based on cancer potential.
Q19. Why had IARC rated AN as a probable human carcinogen?
A. The rating was based on early studies that showed evidence of increased cancers of the brain and ear duct in rats. There was little conclusive evidence about whether or not AN caused cancer in humans. That is not the case, today, thanks to four major studies completed in 1997-98 showing no evidence of an overall increased risk for cancer death or any other cause of death for acrylonitrile workers. Please contact IARC for more information.
Q20. Did industry pressure cause IARC act so quickly to change the rating?
A. Industry did not pressure IARC. In fact, IARC had actually planned to review AN a few years earlier, but waited for the NCI study to be finished. It's likely IARC would've acted just as quickly if results had shown that AN was cancerous.
Q21. What is the union's opinion of the NCI study and IARC rating?
A. While we cannot speak for the unions at our plants, we think it is safe to say they were pleased with the NCI study findings and the IARC reclassification.
Q22. What will happen if follow-up studies of workers after 1989 conclude that AN causes cancer? Will IARC change its rating again?
A. Though it's impossible to speculate on future studies, we don't expect follow-up studies to show higher levels of cancer in AN workers than would normally be found among the general population.
Q23. Will industry lobby for relaxed workplace standards because of the new IARC rating? What about construction of new plants? Will you use the existing safety standards or less stringent standards?
A. We don't expect any relaxing of standards. The completeness of the NCI study provides us with great assurances that current standards are doing their job.
Sources of additional information:
* AN Group - Bob Fensterheim, web site
* IARC, NCI web site
* "The Mortality of Acrylonitrile Workers - New Evidence and a Review of the Old," Scandinavian Journal of Work, Environment & Health, Vol. 24, Sup. 2, 1998.
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