Documents Lemen, Richard A. 5 results

"The silicate mineral asbestos is categorized into two main groups based on fiber structure: serpentine asbestos (chrysotile) and amphibole asbestos (crocidolite, amosite, anthophyllite, tremolite, and actinolite). Chrysotile is used in more than 2 000 applications and is especially prevalent in the construction industry. Although its use is banned or restricted in more than 52 countries, an estimated 107 000 workers die from asbestos exposure each year, and approximately 125 million workers continue to be exposed. Furthermore, ambient exposures persist to which the public is exposed, globally. Today, the primary controversies regarding the use of asbestos are the potencies of different types of asbestos, as opposed whether or not asbestos causes morbidity and mortality. The asbestos industry has promoted and funded research based on selected literature, ignoring both clinical and scientific knowledge. In this piece, we highlight a prominent example of a conflicted publication that sought to undermine the World Health Organization (WHO) campaign to stop the use of all forms of asbestos, including chrysotile asbestos. Independent and rigorous scientific data provide sufficient evidence that chrysotile asbestos, like other forms of asbestos, is a cause of asbestos-related morbidity and premature mortality."

"Clinical and public health research, education, and medical practice are vulnerable to influence by corporate interests driven by the for-profit motive. Developments over the last 10 years have shown that transparency and self-reporting of corporate ties do not always mitigate bias. In this article, we provide examples of how sound scientific reasoning and evidence-gathering are undermined through compromised scientific enquiry resulting in misleading science, decision-making, and policy intervention. Various medical disciplines provide reference literature essential for informing public, environmental, and occupational health policy. Published literature impacts clinical and laboratory methods, the validity of respective clinical guidelines, and the development and implementation of public health regulations. Said literature is also used in expert testimony related to resolving tort actions on work-related illnesses and environmental risks. We call for increased sensitivity, full transparency, and the implementation of effective ethical and professional praxis rules at all relevant regulatory levels to rout out inappropriate corporate influence in science. This is needed because influencing the integrity of scientists who engage in such activities cannot be depended upon."

The evidence for the association between occupational chrysotile (12001295) exposure and cancer was reviewed to evaluate the amphibole hypothesis which proposed that the mesotheliomas observed among workers exposed to chrysotile may actually be caused by contamination by relatively low concentrations (below 1%) of tremolite (77536686) fibers. The review considered evidence obtained in studies investigating chrysotile lung burdens, epidemiologic and laboratory animal studies investigating asbestos carcinogenicity, and mechanistic studies. Low concentrations of chrysotile fibers have been found in the lungs of asbestos workers, even those who worked primarily in chrysotile producing industries. Unexpectedly high concentrations of amphibole asbestos (1332214) forms were found. These findings provided the primary basis for the amphibole hypothesis. Most case/control studies investigating associations between asbestos lung burdens and mesothelioma risk have found clear dose response relationships with amphibole lung burdens, but not chrysotile lung burdens. Some studies, however, have found associations between mesothelioma risk and chrysotile lung burdens. Both epidemiological and experimental studies have shown that chrysotile can cause lung cancer and mesothelioma and that its carcinogenic activity was not due to contamination with tremolite. Some of the epidemiologic evidence has indicated that chrysotile may be less potent than the amphiboles in causing mesothelioma. The experimental animal evidence showed than when expressed on a per weight basis, chrysotile fibers are as at least as potent as amphibole asbestos fibers in causing lung cancer. The authors conclude that the toxicologic and epidemiologic literature strongly support the view that occupational exposure to chrysotile increases the risk of lung cancer and mesothelioma. It is considered prudent that chrysotile be treated with the same level of concern as the amphibole forms of asbestos.

"Background Efforts have been made for 25 years to develop asbestos risk assessments that provide valid information about workplace and community cancer risks. Mathematical models have been applied to a group of workplace epidemiology studies to describe the relationships between exposure and risk. EPA's most recent proposed method was presented at a public meeting in July 2008.Methods Risk assessments prepared by USEPA, OSHA, and NIOSH since 1972 were reviewed, along with related literature. Results and Conclusions None of the efforts to use statistical models to characterize relative cancer potencies for asbestos fiber types and sizes have been able to overcome limitations of the exposure data. Resulting uncertainties have been so great that these estimates should not be used to drive occupational and environmental health policy. The EPA has now rejected and discontinued work on its proposed methods for estimating potency factors. Future efforts will require new methods and more precise and reliable exposure assessments. However, while there may be genuine need for such work, a more pressing priority with regard to the six regulated forms of asbestos and other asbestiform fibers is to ban their production and use."