The petrochemical industry was alerted decades ago that asbestos, a fibrous mineral, and benzene, a solvent, could cause cancer and other diseases. Yet products containing asbestos
(insulation) and benzene (gasoline, oils, synthetic rubber, paints, plastics) continued to be widely used and manufactured in refineries and chemical plants. They are still present in the workplace today, though heavily regulated. These chronologies are based on medical and government literature and the internal documents of companies and professional associations:

ASBESTOS

1918: Frederick Hoffman, a medical statistician for the Prudential Life Insurance Co., reports in a U.S. Department of Labor bulletin that American and Canadian life insurance companies
generally deny coverage to asbestos workers "on account of the assumed health-injurious conditions of the industry."

1922: Louis Dublin, a statistician for the Metropolitan Life Insurance Co., writes that asbestos workers are at risk of fibrosis -- the formation of fibrous tissue in the lungs -- as well as other
ailments.

1936: Congress passes the Walsh-Healy Act, forbidding companies doing more than $10,000 in business with the federal government to subject workers to hazardous conditions.

1937: Roy Bonsib, chief safety inspector for Standard Oil Co. of New Jersey, documents illnesses such as asbestosis and analyzes the dust-creating potential of installing and removing insulation.

1937-38: The Industrial Hygiene Digest of the Industrial Hygiene Foundation abstracts eight articles about asbestosis and two about "industrial cancer" among asbestos workers.

1944: The Journal of the American Medical Association reports that asbestos is among "agents known or suspected to cause occupational cancer."

1948: The American Petroleum Institute's Medical Advisory Committee, whose members represent oil giants, receives a summary of a paper in which Dr. W.C. Hueper, former chief pathologist for E.I. DuPont de Nemours & Co., suggested that the industry "aim at the complete elimination of the exposure" to asbestos and benzene.

1960: Dr. A.J. Fleming and Dr. C.A. D'Alonzo of DuPont report that "pulmonary carcinoma has been observed with such high frequency in employees of the asbestos industry that a causal
relationship has been accepted by most authorities."

1962: Gulf Oil Co. publishes a training manual for insulators, which states: "The fibers of asbestos do not tend to form an air floating dust, so are not injurious to the respiratory organs. Working with this material does not subject one to this hazard to his health." Insulators continue to work unprotected in
many plants.

1964: Dr. Irving Selikoff of Mount Sinai School of Medicine in New York City and two other doctors report that half of 1,117 asbestos workers they examined showed evidence of asbestosis.

1971: The newly created Occupational Safety and Health Administration adopts its first asbestos standard, with a permissible exposure limit (PEL) of 12 fibers per cubic centimeter
of air over an eight-hour workday. 1972: OSHA adopts PEL of 5 fibers per cc. and establishes a
"ceiling" -- the maximum amount to which a worker can be exposed
at any time -- of 10 fibers per cc.

1986: OSHA passes the first asbestos standard specifically for the construction industry, lowering the PEL to .2 fibers per cc.

1994: OSHA lowers the PEL to .1 fibers per cc and requires other measures to protect demolition, renovation and maintenance workers, the people most likely to encounter asbestos.

BENZENE

1926: The National Safety Council's Committee on Benzol (benzene) reports that exposure to benzene usually is followed by a leucopenia, a decrease in white blood cells.

1928: Dr. Alice Hamilton of Harvard University cites the dangers of continuous exposure to small quantities of benzene and recommends periodic medical examinations to detect early symptoms
of poisoning.

1946: The Manufacturing Chemists' Association publishes a "chemical safety data sheet" on benzene, prescribing a variety of steps to reduce exposures and monitor workers for physiological changes.

1948: An American Petroleum Institute benzene review, prepared under the direction of Harvard's Dr. Philip Drinker, says that "the only absolutely safe concentration for benzene is zero." In the oil industry, exposures of hundreds of parts per million are not unusual.

1958: Esso establishes a maximum benzene exposure limit of 25 ppm averaged over an eight-hour workday but admits that "this figure may still be too high."

1960: The API publishes another benzene review, deleting the 1948 statement that the only safe level is zero.

1971: OSHA adopts a permissible exposure limit for benzene of 10 PPM over an eight-hour day.

1978: Based on a recommendation from the National Institute for Occupational Safety and Health, OSHA lowers the benzene PEL to 1 PPM, drawing a fierce legal challenge from the oil, iron and steel industries.

1980: US Supreme Court rules that OSHA must do a risk analysis before adopting the 1 PPM limit.

1986: Several risk analyses in hand, OSHA announces it will again try to lower the PEL to 1 PPM NIOSH says new scientific evidence suggests the PEL should be 10 times lower -- .1 PPM

1987: OSHA adopts the 1 PPM standard with no organized industry opposition.

1989: OSHA's Corpus Christi Area Office begins a "local emphasis program" for benzene. It issues citations to eight petroleum-related companies, including four refineries, for benzene-related violations.

1989: Shaken by a federal jury's $100 million verdict against Monsanto in a leukemia case, attorneys for Shell prepare briefing papers for other industry lawyers on how to defend against benzene litigation. One suggestion is to "avoid unnecessary or inadvertent disclosure of sensitive documents."

1994: The American Conference of Governmental Industrial Hygienists, an influential group whose "threshold limit values" for chemicals are widely used around the world, proposes a TLV of .3 for benzene, retreating from a 1990 plan to lower it to .1.