Chris Gray

Leukemia Risk Associated With Low-Level Benzene Exposure

Background: Men who were part of an Australian petroleum industry cohort had previously been found to have an excess of lympho-hematopoietic cancer. Occupational benzene exposure is a possible cause of this excess. Methods: We conducted a case-control study of lympho-hematopoietic cancer nested within the existing cohort study to examine the role of benzene exposure. Cases identified between 1981 and 1999 (N = 79) were age-matched to 5 control subjects from the cohort. We estimated each subject’s benzene exposure using occupational histories, local site-specific information, and an algorithm using Australian petroleum industry monitoring data. Results: Matched analyses showed that the risk of leukemia was increased at cumulative exposures above 2 ppm-years and with intensity of exposure of highest exposed job over 0.8 ppm. Risk increased with higher exposures; for the 13 case-sets with greater than 8 ppm-years cumulative exposure, the odds ratio was 11.3 (95% confidence interval = 2.85-45.1). The risk of leukemia was not associated with start date or duration of employment. The association with type of workplace was explained by cumulative exposure. There is limited evidence that short-term high exposures carry more risk than the same amount of exposure spread over a longer period. The risks for acute nonlymphocytic leukemia and chronic lymphocytic leukemia were raised for the highest exposed workers. No association was found between non-Hodgkin lymphoma or multiple myeloma and benzene exposure, nor between tobacco or alcohol consumption and any of the cancers. Conclusions: We found an excess risk of leukemia associated with cumulative benzene exposures and benzene exposure intensities that were considerably lower than reported in previous studies. No evidence was found of a threshold cumulative exposure below which there was no risk.

Validation of exposure estimation for benzene in the Australian petroleum industry

A nested case-control study was undertaken to investigate whether an excess of lympho-haematopoietic cancers in the Australian petroleum industry was associated with benzene exposure. The benzene exposures of the cases and controls were estimated using a quantitative algorithm based largely on exposures measured in the Australian petroleum industry. The algorithm was used to estimate, for each subject, the benzene exposure in parts per million (ppm) for each job held in the industry, and the cumulative exposure in ppm years. Because of the critical importance of the exposure assessment in this design of epidemiological study, particular attention was paid to the reliability of the inputs to the algorithm. The inputs [base estimates (BEs) of exposure and technology-specific exposure modifiers (EMs)] were compared to data from other sources including the occupational hygiene literature. Where such comparison data were available, they were generally found to confirm the values used in the algorithm, although four input values were changed as a result of the validation exercise. The integrity of the task-based algorithm was validated by employing it to calculate the exposures of the tanker drivers in the study and comparing these with measured daily exposure for tanker drivers in the Australian petroleum industry and exposure values found in the occupational hygiene literature. After adjustment for the mix of products carried by the Australian tanker drivers, the estimates from the algorithm were found to be comparable to the measured and literature values. This exercise provided evidence that the exposure assessment for the epidemiological study was reliable and that the results of the study can be used as the basis for evaluating the relationship between exposure to benzene and the risk of lympho-haematopoietic cancer.

The health watch case-control study of leukemia and benzene : The story so far

Abstract:  A case–control study nested in the Health Watch cohort of petroleum industry workers, investigated whether the excess of lymphohematopoetic cancers, identified among male members of the Health Watch cohort, was associated with benzene exposure. Cases of non‐Hodgkins lymphoma (n= 31), multiple myeloma (n= 15), and leukemia (n= 33) were identified between 1981 and 1999. Cases were age‐matched to five controls. Exposure was retrospectively estimated for each occupational history using an algorithm in a relational database. Benzene exposure measurements, supplied by Australian petroleum companies, were used to estimate exposure for specific tasks. The tasks carried out within the job, the products handled, and the technology used, were identified from interviews with contemporary colleagues. More than half of the subjects started work after 1965 and had an average exposure period of 20 years. Exposure was low, 85% of the cumulative exposure estimates were <10 ppm years. Matched analyses showed that non‐Hodgkins lymphoma and multiple myeloma were not associated with benzene exposure. Leukemia risk, however, was significantly increased for the subjects with greater than 16 ppm years cumulative exposure, odds ratio (OR) 51.9 (5.6–477) or with greater than 0.8 ppm intensity of highest exposed job. Cumulative exposures were similar to those found in comparable studies. The inclusion of occasional high exposures, for example, as a result of spillages, reduced the ORs, when the exposure was treated as either a continuous or a categorical variable. Our data demonstrate a strong association between leukemia and modest benzene exposure. The choice of cut‐point and reference group has a marked effect on the ORs, but does not change the overall conclusions.

Medicinal plants of Thailand

Introduction For thousands of years, plants have formed the basis of sophisticated traditional medicinal systems in many parts of the world and remain a repository of new remedies for mankind (Gurib-Fakim, 2006). The healing properties of various plants are not only recognized by humans but, amazingly, are also widely utilized by other primates such as monkeys and apes (Halberstein, 2005). These primates have been observed to select for consumption specific botanical species that may act as analgesics, anti-microbials, anti-inflammatories, immunostimulants, anti-diarrheals, digestive aids and fertility regulators (Baker, 1996; Glander, 1994; Plotkin, 2000). It is noteworthy that an interesting review by Huffmann (1997) draws attention to the fact that monkeys, gorillas, chimpanzees as well as humans have been found to use the same plants for the treatment of similar diseases, injuries and other health problems.

Structure and Validation of a Pharmacokinetic Model for Benzene

A pharmacokinetic model for benzene has been developed and validated for the inhalation aspects of its operation. The validation shows reasonable agreement between the model outputs and human biological data for phenol in urine, benzene in alveolar air, and benzene in mixed exhaled air.

Commentaries & Analyses — MARKET CAPITALIZATION OF AUSTRALIAN STOCK EXCHANGE (ASX) LISTED BIOTECHNOLOGY COMPANIES

Comments on the market capitalization of Australian Stock Exchange listed biotechnology companies. Background on the Australian biotechnology stock market; Factors which determine the levels of risks; Points to consider when valuing Australian biotechnology companies.

Current status of bioindustry in South Korea

The article is about the research portfolio of South Korea. It also touches on South Koreas competitive edge over other Asia countries. It includes a table on the South Korean Bioindustry Sectors.