Manipulated Data in Shell's Benzene Historical Exposure Study

In 1983, in the face of mounting evidence of excess leukemia among workers at Shell Oil's Wood River (IL) and Deer Park (TX) petroleum refineries, Shell initiated the Benzene Historical Exposure Study (BHES). Shell's prior research had implicated occupational exposure to benzene as the source of the excess leukemia. The BHES report submission, which ultimately found no link between exposure and the excess morbidity, coincided with OSHA's planned hearings over a new regulatory standard for benzene. Over the next two decades, Shell published several papers based on or expanding the BHES data, all of which concluded that the excess of leukemia was unrelated to benzene. A review of the raw data on which Shell and its consultants relied reveals that Shell manipulated and omitted data in order to reach conclusions that exculpated it from liability and helped delay stricter benzene regulation.

Benzene-induced cancers: abridged history and occupational health impact

Benzene-induced cancer in humans was first reported in the late 1920s. Carcinogenesis findings in animals were not reported conclusively until 1979. Industry exploited this "discrepancy" to discredit the use of animal bioassays as surrogates for human exposure experience. The cardinal reason for the delay between first recognizing leukemia in humans and sought-after neoplasia in animals centers on poor design and conduct of experimental studies. The first evidence of carcinogenicity in animals manifested as malignant tumors of the zymbal glands (sebaceous glands in the ear canal) of rats, and industry attempted to discount this as being irrelevant to humans, as this organ is vestigial and not present per se in humans. Nonetheless, shortly thereafter benzene was shown to be carcinogenic to multiple organ sites in both sexes of multiple strains and multiple species of laboratory animals exposed via various routes. This paper presents a condensed history of the benzene bioassay story with mention of benzene-associated human cancers.

Airborne concentrations of benzene associated with the historical use of some formulations of liquid wrench

The current study characterizes potential inhalation exposures to benzene associated with the historical use of some formulations of Liquid Wrench under specific test conditions. This product is a multiuse penetrant and lubricant commonly used in a variety of consumer and industrial settings. The study entailed the remanufacturing of several product formulations to have similar physical and chemical properties to most nonaerosol Liquid Wrench formulations between 1960 and 1978. The airborne concentrations of benzene and other constituents during the simulated application of these products were measured under a range of conditions. Nearly 200 breathing zone and area bystander air samples were collected during 11 different product use scenarios. Depending on the tests performed, average airborne concentrations of benzene ranged from approximately 0.2-9.9 mg/m(3) (0.08-3.8 ppm) for the 15-min personal samples; 0.1-8 mg/m(3) (0.04-3 ppm) for the 1-hr personal samples; and 0.1-5.1 mg/m(3) (0.04-2 ppm) for the 1-hr area samples. The 1-hr personal samples encompassed two 15-min product applications and two 15-min periods of standing within 5 to 10 feet of the work area. The measured airborne concentrations of benzene varied significantly based on the benzene content of the formulation tested (1%, 3%, 14%, or 30% v/v benzene) and the indoor air exchange rate but did not vary much with the base formulation of the product or the two quantities of Liquid Wrench used. The airborne concentrations of five other volatile chemicals (ethylbenzene, toluene, total xylenes, cyclohexane, and hexane) were also measured, and the results were consistent with the volatility and concentrations of these chemicals in the product tested. A linear regression analysis of air concentration compared with the chemical mole fraction in the solution and air exchange rate provided a relatively good fit to the data. The results of this study should be useful for evaluating potential inhalation exposures to benzene and other volatile chemicals that occurred during the past use of some formulations of Liquid Wrench and perhaps for some similar products containing these chemicals.

An overview of published benzene exposure data by industry in China, 1960-2003

This article presents an overview of occupational benzene exposures in China based on data published in Chinese medical journals. The data were derived from 384 reports of benzene poisoning or industrial hygiene surveys published in Chinese medical journals between 1960 and 2003. The following information was extracted whenever available: industry, occupation, task, date, benzene levels, sampling location, workplace descriptions and, for case reports, medical diagnosis. Each paper provided one or more sets of benzene data, each set representing a sampling location or job title with one to several measurements including, mainly, breathing zone area concentration measurements, and much less frequently personal monitoring. Two criteria based on data quality were applied to select suitable data for analyses. The selected exposure data were analyzed by industry and time period. Nine hundred five sets of benzene measurements from 72 industries were reported in the 384 papers selected for this review, and 621 sets (68.6%) presented average benzene concentrations, which covered 55 industries. The distribution of the reported average benzene exposures was skewed with a median of 51.5 mg/m3. The average benzene concentrations were below 100 mg/m3 for 406 (65%) of the 621 reported average concentrations. The medians of the reported averages in mg/m3 for the five industries with the highest exposures were: 124.8 for leather products, 98.7 for electronic devices, 75.4 for machinery, 50.4 for shoes, and 50.3 for office supplies and sports equipment manufacturing. These data describe the concentrations and changing patterns of occupational benzene exposure by industry and time period in China.

Carcinogenic effects of benzene: Cesare Maltoni's contributions

Cesare Maltoni's contributions to understanding, identifying, and characterizing widely used commercial chemicals in experimental animals are among the most important methods developed in the history of toxicology and serve to protect working men and women, the general population, and our environment from hazardous substances. Maltoni developed experimental methods that have reached the "platinum standard" for protection of public health. Benzene was among the 400 or more chemicals that Maltoni and his associates tested for carcinogenicity. In 1976, Maltoni reported that benzene is a potent experimental carcinogen. Maltoni's experiments clearly demonstrated that benzene is carcinogenic in Sprague-Dawley rats, Wistar rats, Swiss mice, and RF/J mice when administered by inhalation or ingestion. Benzene caused carcinomas of the Zymbal gland, oral cavity, nasal cavities; cancers of the skin, forestomach, mammary glands, and lungs; angiosarcomas and hepatomas of the liver; and hemolymphoreticular cancers. Thus, benzene was shown to be a multipotential carcinogen that produced cancers in several species of animals by various routes of administration. On November 2, 1977, Chemical Week reported that Maltoni provided a "bombshell" when he demonstrated the "first direct link" between benzene and cancer. In this paper, I shall summarize early experiments and human studies and reports; Maltoni's experimental contribution to understanding the carcinogenicity of benzene in humans and animals; earlier knowledge concerning benzene toxicity; and benzene standards and permissible exposure levels.

Measurement of benzene in the workplace and its evolution process, Part I: Overview, history, and past methods

Benzene and its measurement continues to be important in the field of industrial hygiene. This two-part article reviews the history of occupational and environmental sampling and analysis of benzene from the early 1900s to the present. Part I provides an overview and details of the methods used in the past; history of the American Conference of Governmental Industrial Hygienists' threshold limit values for benzene; and reviews portable, grab, and integrated sampling methods as well as the various analytical methods. It is important to review and understand the past in order to predict future trends.

[Kekulé's dream. Additional observations on the "benzol ring"]

20 years ago, Alexander Mitscherlich published in this journal a brief psychological study of the famous dream the chemist Friedrich August Kekulé had immediately before putting forward his representation of the benzene molecule in the "Kekulé formula". Mitscherlich (among whose forebears a number of prominent chemists figured) interpreted the dream as an expression of a frustrated and repressed sexual desire. The present author, by contrast, favours an interpretation which shifts the focus away from the suggestive power of the dream image-a snake biting its own tail-and sees Kekulé's dream production as a reflection of the psychic effort it cost him to ward off latent feelings of guilt associated with the early death of his wife and to alleviate scruples of conscience about his own achievement.

Benzene: a multipotential carcinogen. Results of long-term bioassays performed at the Bologna Institute of Oncology

Until recently, the incidence of benzene carcinogenicity was based only on the association between benzene occupational exposure and human leukemia, with many limited case reports and scanty epidemiological data. Available experimental studies up to 1976 on animals were rare, fragmentary, and inadequate, and had failed to prove the carcinogenic effects of benzenes. However, an integrated project of long-term carcinogenicity bioassays, begun in our laboratory in 1976 and still continuing, has shown that benzene produces a variety of tumors in rats including Zymbal gland carcinomas, carcinomas of the oral cavity, hepatocarcinomas, and possibly mammary carcinomas, lymphoreticular neoplasias, and other malignancies. Some of the tumors caused by benzene are uncommon or unusual in the breed of rats studied. Therefore benzene must be considered, under the studied experimental conditions, a strong multipotential carcinogen. The need for more experimental research is emphasized, particularly to assess the carcinogenic effects of low doses. Also recommended are more comprehensive epidemiological investigations, extended to all types of malignancies, and the application of adequate measures for primary prevention.