Living in a chemical world: actions and reactions to industrial carcinogens

Oxidative stress--implications, source and its prevention

Oxidative stress has been a major predicament of present day living. It has been the product of imbalance between the processes involved in free radical generation and their neutralization by enzymatic and non-enzymatic defence mechanisms. The oxidative stress has been contributed by numerous factors including heavy metals, organic compound-rich industrial effluents, air pollutants and changing lifestyle pattern focussing mainly on alcohol consumption, dietary habits, sun exposure, nuclear emissions, etc. The most common outcome of oxidative stress is the increased damage of lipid, DNA and proteins that resulted in the development of different pathologies. Among these pathologies, cancer is the most devastating and linked to multiple mutations arising due to oxidative DNA and protein damage that ultimately affect the integrity of the genome. The chemopreventive agents particularly nutraceuticals are found to be effective in reducing cancer incidences as these components have immense antioxidative, antimutagenic and antiproliferative potentials and are an important part of our dietary components. These secondary metabolites, due to their unique chemical structure, facilitate cell-to-cell communication, repair DNA damage by the downregulation of transcription factors and inhibit the activity of protein kinases and cytochrome P450-dependent mixed function oxidases. These phytochemicals, therefore, are most appropriate in combating oxidative stress-related disorders due to their tendency to exert better protective effect without having any distinct side effect.

In vivo genotoxicity of alcohol consumption and lead exposure in printing press workers

The objective of the present study was to evaluate the genotoxicity of a double exposure to alcohol and lead in subjects from the printing industry, and the possible interaction between the two agents. Individuals were classified into four different groups: controls, lead-exposed individuals, alcohol consumers, and lead-exposed alcohol consumers. Chromosomal analysis was carried out according to conventional methods and data on chromosome aberrations and sister chromatid exchanges (SCEs) were obtained for each individual. Alcohol consumers had a significant increase in the frequency of SCEs compared to the controls. Though there was an increase in the frequency of chromosome aberrations and SCEs in individuals exposed to lead, it was not significant. Statistical analysis did not reveal an interaction between alcohol and lead in either assay.

In vivo genotoxic effects of smoking and occupational lead exposure in printing press workers

The objective of the present study was to evaluate the genotoxicity of a combination exposure to lead and smoking in workers from the printing industry and also to examine the possible interaction between the two agents. Individuals were classified into 4 different groups: control group, lead-exposed group, smokers and the double-exposure group. Chromosomal analysis was carried out according to conventional methods. Our preliminary study shows that lead-exposed individuals had a significantly increased frequency of sister chromatid exchanges. Further, double exposure to smoking and lead inhibits mitosis.

Evaluation of the national cancer program and proposed reforms

A statement by some 68 prominent national experts in industrial medicine, carcinogenesis, epidemiology, and public health, released at a February 4, 1992 press conference in Washington, D.C., charged that the National Cancer Institute (NCI) has confused the public by repeated claims of winning the war against cancer. In fact, age standardized incidence rates have increased sharply over recent decades, while ability to treat and cure most cancers has not materially improved. Furthermore, the NCI has minimized evidence for increasing cancer rates which are largely attributed to smoking and to diet. In so doing, NCI trivializes the importance of occupational carcinogens as non-smoking-attributable causes of lung and other cancers, and ignores the tenuous and inconsistent evidence for the causal role of diet per se and also the important role of carcinogenic dietary contaminants. Reflecting this near exclusionary blame-the-victim theory of cancer causation, with support from the American Cancer Society and industry, the NCI discounts the role of avoidable involuntary exposures to industrial carcinogens in air, water, food, the home, and the workplace. The NCI has also failed to provide scientific guidance to Congress and regulatory agencies on fundamental principles of carcinogenesis and epidemiology, and on the critical need to reduce avoidable exposures to environmental and occupational carcinogens. Contrary to NCI, analysis of their $2 billion budget reveals very limited allocations for research on primary cancer prevention, and for occupational cancer which receives only $19 million annually, 1% of NCI's total budget. Problems of professional mindsets in NCI leadership--fixation on diagnosis, treatment, and basic research (much of questionable relevance) and the neglect of cancer prevention--are exemplified by the composition of the Executive President's Cancer Panel and the National Cancer Advisory Board. Contrary to the explicit mandate of the National Cancer Act, the Board is virtually devoid of recognized authorities in occupational and environmental carcinogenesis. These problems are further compounded by institutionalized conflicts of interest reflected in the composition of past Cancer Panels, and of the current Board of Overseers of the Memorial Sloan Kettering Cancer Center, NCI's prototype comprehensive cancer center, with their closely interlocking financial interests with the cancer drug and other industries. Comprehensive reforms of NCI policies and priorities are overdue. Implementation of such reforms is, however, unlikely in the absence of further support from industrial medicine professionals, which is here solicited, besides action by Congress and concerned citizen groups.

Evaluation of the national cancer program and proposed reforms

A statement by 68 prominent national experts in cancer prevention, carcinogenesis, epidemiology, and public health, released at a February 4, 1992, press conference in Washington, D.C., charged that the National Cancer Institute (NCI) has misled and confused the public by repeated claims of winning the war against cancer. In fact, age-standardized incidence rates have escalated to epidemic proportions over recent decades, while the ability to treat and cure most cancers has not materially improved. Furthermore, the NCI has minimized evidence for increasing cancer rates, which are largely attributed to smoking, trivializing the importance of occupational carcinogens as non-smoking attributable causes of lung and other cancers, and to diet per se, in spite of tenuous and inconsistent evidence and ignoring the important role of carcinogenic dietary contaminants. Reflecting this near exclusionary blame-the-victim theory of cancer causation, with lockstep support from the American Cancer Society and industry, the NCI discounts the role of avoidable involuntary exposures to industrial carcinogens in air, water, food, the home, and the workplace. The NCI has also failed to provide any scientific guidance to Congress and regulatory agencies on fundament principles of carcinogenesis and epidemiology, and on the critical needs to reduce avoidable exposures to environmental and occupational carcinogens. Analysis of the +2 billion NCI budget, in spite of fiscal and semantic manipulation, reveals minimal allocations for research on primary cancer prevention, and for occupational cancer, which receives only +19 million annually, 1 percent of NCI's total budget. Problems of professional mindsets in the NCI leadership, fixation on diagnosis, treatment, and basic research, much of questionable relevance, and the neglect of cancer prevention, are exemplified by the composition of the National Cancer Advisory Board. Contrary to the explicit mandate of the National Cancer Act, the Board is devoid of members authoritative in occupational and environmental carcinogenesis. These problems are further compounded by institutionalized conflicts of interest reflected in the composition of past executive President's Cancer Panels, and of the current Board of Overseers of the Sloan-Kettering Memorial Cancer Center, the NCI's prototype comprehensive cancer center, with their closely interlocking financial interests with the cancer drug and other industries. Drastic reforms of NCI policies and priorities are long overdue. Implementation of such reforms is, however, unlikely in the absence of further support from industrial medicine professionals, besides action by Congress and concerned citizen groups.

Ethylene oxide. An occupational health hazard for hospital workers

Hospitals present a variety of infectious, chemical, and physical hazards at levels comparable to the hazards encountered in many industries. Our society has acquired the scientific and technological capability to identify and abate hazardous chemical exposures. Thus, the knowledge needed to resolve the problem effectively is available, and now, it only needs to be applied. The knowledge related to EtO can be summarized into three major points. Exposure to EtO can result in cancer, reproductive abnormalities including genetic damage, and neurological disease. Prevention of exposure to EtO requires sensitive and informed hospital administrators, adequate aeration and ventilation, personal and area monitoring, a written compliance program, and employee information and education. Perioperative nurses must protect their patients and the perioperative team from potential hazards of EtO.

Mutagenic and carcinogenic potency indices and their correlation

We have analyzed a significant number of studies existing in the literature, in which the ability of different short-term tests for predicting carcinogenicity in rodents was investigated. We have separated these studies into two groups. In the better known group of studies, qualitative predictivity was investigated (sensitivity and specificity). In the second group of studies (analyzed in greater detail), positive results were examined for the correlation between carcinogenic potency and potency of response in a given short-term test. There is substantial agreement between qualitative and quantitative predictivity; both appear to be situated between a low and moderate level. We have analyzed the interesting possibility of using the quantitative approach not only for positive data but for combined positive and negative data as well. We have stressed that short-term tests of genotoxicity should be asked to predict only initiation and irreversible alterations in the genome and not to predict a combination of these events, including promotion and modulation of differentiation. Even with regard to only initiation, genotoxicity data should be related to comparative metabolism, as well as to considerations of the significance of different end points and structure-activity relationship data. In conclusion, the information coming from short-term tests of genotoxicity is probably useful but should be used in conjunction with other types of information and only for predicting one particular class of events in the entire process of carcinogenesis.