The Experts below are selected from a list of 195 Experts worldwide ranked by ideXlab platform
Lyly Teppo - One of the best experts on this subject based on the ideXlab platform.
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health effects of cadmium exposure a review of the literature and a risk estimate
Scandinavian Journal of Work Environment & Health, 1998Co-Authors: Lyly TeppoAbstract:Environmental exposures occupy an important position in cancer causation. Even if the etiologic fractions associated with various life-style factors such as smoking, diet, alcohol consumption, and sexual habits may, according to current knowledge, be greater than those of exposures occurring in the human environment, it is often easier to change the environment than to make individuals change their life-style and habits into healthier modes. Through legislation and various technical measures it is often possible to regulate the occurrence of different carcinogenic agents in the human environment and to diminish exposures to them as has been done with, for example, carcinogens at workplaces, ionizing radiation, and ambient air and water pollution. Before regulatory measures can be undertaken, the individual exposures and their relative importance should be known. Useful information is obtained through laboratory research, but its relevance in the human setting should, when possible, be confirmed on the population level, that is, by using epidemiologic methods. Such questions as how high are the relative risks associated with exposures that occur in real life, how long are the latencies, and are there important interactions need to be answered. In countries and areas where a well-functioning cancer registry exists, epidemiologic cancer research is greatly facilitated. If a cohort defined by exposure to a suspected agent can be created, cases of cancer can be identified for the registry files by applying usual cohort study methodology. Cancer registry may also be able to produce unbiased case series for case-referent studies, and these data are especially important when rare cancers are concerned. (The number of cases would be too small in any cohort study.) Quite often, a case-referent approach within a cohort is used. In each Nordic Country there is a cancer registry covering the entire population of the Country, and the individual person numbers available in the countries make the record linkage between study cohorts and registry files a technically easy procedure, and it has been successfully used in a large number of epidemiologic studies on both the national and Nordic level. Confidentiality rules concerning the registries are reasonable and have not caused undue problems for appropriate epidemiologic studies. The Nordic cancer registries have participated in several studies in which environmental exposures have been analyzed in terms of cancer risks. In Finland, both cohort studies and case-referent studies have been conducted, recently focusing, for example, on low-intensity magnetic fields produced by high-voltage powerlines (only a marginal increase in the risk of adult leukemia found), chlorophenols in drinking water after leakage from a sawmill (risk of non-Hodgkin's lymphoma slightly increased), and ionizing radiation caused by radon daughters from the earth (suggestive increase in the risk of lung cancer) or by fallout from the Chernobyl accident (no increase in the risk of childhood leukemia). Further studies in which data from cancer registries have been successfully utilized include an evaluation of the cancer risks associated with several exposures in the work environment, the risk of leukemia among people who live close to an oil refinery, the risk of cancer associated with the mutagenicity of drinking water due to chlorination procedures, and the risk of sarcoma and other cancers among herbicide users. In this issue of the Scandinavian Journal of Work, Environment & Health , a review article is published on environmental risk factors in breast cancer by Esther A Welp and her co-workers. In their conclusions, the authors end with several proposals for future studies. These proposals are well focused. Breast cancer is one of the most common cancers in the western world. In spite of extensive research carried out for decades in all parts of the world, simple effective preventive measures are still lacking. The strongest risk factors that have been found are related to endogenous estrogen load and the reproductive history of women, but these factors can only explain a part of all breast cancers. Moreover, even if many of these factors are well characterized, it is difficult, if not impossible, to utilize them in prevention. Thus better understanding of the environmental risk factors for breast cancer would be extremely important. Although the relative risks associated with them are probably low, a large number of women are likely to be exposed, the result being substantial numbers of preventable cancers. One group of chemicals in the human environment that is of interest in terms of breast cancer causation is the group of so-called hormone disruptors. They are compounds with weak estrogenic effects in animal experiments or in vitro studies. Examples of these chemicals are organochlorine compounds (DDT, PCB, etc), phthalates, tributyltin compounds, and alkylphenols. They occur in pesticides, paints and plastic products, anti-fouling agents, and many other products used in a variety of ways. Many people are exposed to them in their workplaces and everyday life -- often without knowing it. An association between hormone disruptors and male infertility, cryptorchidism, and testis cancer has been suggested, and epidemiologic studies on these issues have been made. In addition the hypothesis of a link between exposure to hormone disruptors and breast cancer is biologically plausible. Data supporting this association are increasing, but problems will arise even in well-designed epidemiologic studies. Reliable data on life-long exposures to hormone disruptors are difficult to obtain, and studies based on chemical analyses of fat tissue from cases and referents (aiming at estimation of exposures) have their limitation. Still almost everyone in western populations is exposed to them at least to some extent. Collaboration between different areas is needed in modern cancer epidemiologic research. Solving the problem of the association between hormone disruptors and breast cancer causation calls for cooperation between epidemiologists, chemists, endocrinologists, cell biologists, and experts in gene research. And behind all these are the cancer registers with their data on cancer patients, which may be helpful in certain approaches.
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health effects of cadmium exposure a review of the literature and a risk estimate
Scandinavian Journal of Work Environment & Health, 1998Co-Authors: Lyly TeppoAbstract:Environmental exposures occupy an important position in cancer causation. Even if the etiologic fractions associated with various life-style factors such as smoking, diet, alcohol consumption, and sexual habits may, according to current knowledge, be greater than those of exposures occurring in the human environment, it is often easier to change the environment than to make individuals change their life-style and habits into healthier modes. Through legislation and various technical measures it is often possible to regulate the occurrence of different carcinogenic agents in the human environment and to diminish exposures to them as has been done with, for example, carcinogens at workplaces, ionizing radiation, and ambient air and water pollution. Before regulatory measures can be undertaken, the individual exposures and their relative importance should be known. Useful information is obtained through laboratory research, but its relevance in the human setting should, when possible, be confirmed on the population level, that is, by using epidemiologic methods. Such questions as how high are the relative risks associated with exposures that occur in real life, how long are the latencies, and are there important interactions need to be answered. In countries and areas where a well-functioning cancer registry exists, epidemiologic cancer research is greatly facilitated. If a cohort defined by exposure to a suspected agent can be created, cases of cancer can be identified for the registry files by applying usual cohort study methodology. Cancer registry may also be able to produce unbiased case series for case-referent studies, and these data are especially important when rare cancers are concerned. (The number of cases would be too small in any cohort study.) Quite often, a case-referent approach within a cohort is used. In each Nordic Country there is a cancer registry covering the entire population of the Country, and the individual person numbers available in the countries make the record linkage between study cohorts and registry files a technically easy procedure, and it has been successfully used in a large number of epidemiologic studies on both the national and Nordic level. Confidentiality rules concerning the registries are reasonable and have not caused undue problems for appropriate epidemiologic studies. The Nordic cancer registries have participated in several studies in which environmental exposures have been analyzed in terms of cancer risks. In Finland, both cohort studies and case-referent studies have been conducted, recently focusing, for example, on low-intensity magnetic fields produced by high-voltage powerlines (only a marginal increase in the risk of adult leukemia found), chlorophenols in drinking water after leakage from a sawmill (risk of non-Hodgkin's lymphoma slightly increased), and ionizing radiation caused by radon daughters from the earth (suggestive increase in the risk of lung cancer) or by fallout from the Chernobyl accident (no increase in the risk of childhood leukemia). Further studies in which data from cancer registries have been successfully utilized include an evaluation of the cancer risks associated with several exposures in the work environment, the risk of leukemia among people who live close to an oil refinery, the risk of cancer associated with the mutagenicity of drinking water due to chlorination procedures, and the risk of sarcoma and other cancers among herbicide users. In this issue of the Scandinavian Journal of Work, Environment & Health , a review article is published on environmental risk factors in breast cancer by Esther A Welp and her co-workers. In their conclusions, the authors end with several proposals for future studies. These proposals are well focused. Breast cancer is one of the most common cancers in the western world. In spite of extensive research carried out for decades in all parts of the world, simple effective preventive measures are still lacking. The strongest risk factors that have been found are related to endogenous estrogen load and the reproductive history of women, but these factors can only explain a part of all breast cancers. Moreover, even if many of these factors are well characterized, it is difficult, if not impossible, to utilize them in prevention. Thus better understanding of the environmental risk factors for breast cancer would be extremely important. Although the relative risks associated with them are probably low, a large number of women are likely to be exposed, the result being substantial numbers of preventable cancers. One group of chemicals in the human environment that is of interest in terms of breast cancer causation is the group of so-called hormone disruptors. They are compounds with weak estrogenic effects in animal experiments or in vitro studies. Examples of these chemicals are organochlorine compounds (DDT, PCB, etc), phthalates, tributyltin compounds, and alkylphenols. They occur in pesticides, paints and plastic products, anti-fouling agents, and many other products used in a variety of ways. Many people are exposed to them in their workplaces and everyday life -- often without knowing it. An association between hormone disruptors and male infertility, cryptorchidism, and testis cancer has been suggested, and epidemiologic studies on these issues have been made. In addition the hypothesis of a link between exposure to hormone disruptors and breast cancer is biologically plausible. Data supporting this association are increasing, but problems will arise even in well-designed epidemiologic studies. Reliable data on life-long exposures to hormone disruptors are difficult to obtain, and studies based on chemical analyses of fat tissue from cases and referents (aiming at estimation of exposures) have their limitation. Still almost everyone in western populations is exposed to them at least to some extent. Collaboration between different areas is needed in modern cancer epidemiologic research. Solving the problem of the association between hormone disruptors and breast cancer causation calls for cooperation between epidemiologists, chemists, endocrinologists, cell biologists, and experts in gene research. And behind all these are the cancer registers with their data on cancer patients, which may be helpful in certain approaches.
Johan Karrholm - One of the best experts on this subject based on the ideXlab platform.
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homogeneity in prediction of survival probabilities for subcategories of hipprosthesis data the Nordic arthroplasty register association 2000 2013
Clinical Epidemiology, 2019Co-Authors: Christoffer Bartzjohannessen, Ove Furnes, Anne Marie Fenstad, Stein Atle Lie, Alma B Pedersen, Soren Overgaard, Johan KarrholmAbstract:Introduction: The four countries in the Nordic Arthroplasty Register Association (NARA) share geographic proximity, culture, and ethnicity. Pooling data from different sources in order to obtain higher precision and accuracy of survival-probability estimates is appealing. Nevertheless, survival probabilities of hip replacements vary between the countries. As such, risk prediction for individual patients within countries may be problematic if data are merged. In this study, our primary question was to address when data merging for estimating prosthesis survival in subcategories of patients is advantageous for survival prediction of individual patients, and at what sample sizes this may be advised. Methods: Patients undergoing total hip replacements for osteoarthritis between January 1, 2000 and December 31, 2013 in the four Nordic countries were studied. A total of 184,507 patients were stratified into 360 patient subcategories based on Country, age-group, sex, fixation, head size, and articulation. For each patient category, we determined the sample size needed from a single Country to obtain a more accurate and precise estimate of prosthesis-survival probability at 5 and 10 years compared to an estimate using data from all countries. The comparison was done using mean-square error. Results: We found large variations in the sample size needed, ranging from 40 to 2,060 hips, before an estimate from a single Nordic Country was more accurate and precise than estimates based on the NARA data. Conclusion: Using pooled survival-probability estimates for individual risk prediction may be imprecise if there is heterogeneity in the pooled data sources. By applying mean-square error, we demonstrate that for small sample sizes, applying the larger NARA database may provide a more accurate and precise estimate; however, this effect is not consistent and varies with the characteristics of the subcategory.
Soren Overgaard - One of the best experts on this subject based on the ideXlab platform.
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homogeneity in prediction of survival probabilities for subcategories of hipprosthesis data the Nordic arthroplasty register association 2000 2013
Clinical Epidemiology, 2019Co-Authors: Christoffer Bartzjohannessen, Ove Furnes, Anne Marie Fenstad, Stein Atle Lie, Alma B Pedersen, Soren Overgaard, Johan KarrholmAbstract:Introduction: The four countries in the Nordic Arthroplasty Register Association (NARA) share geographic proximity, culture, and ethnicity. Pooling data from different sources in order to obtain higher precision and accuracy of survival-probability estimates is appealing. Nevertheless, survival probabilities of hip replacements vary between the countries. As such, risk prediction for individual patients within countries may be problematic if data are merged. In this study, our primary question was to address when data merging for estimating prosthesis survival in subcategories of patients is advantageous for survival prediction of individual patients, and at what sample sizes this may be advised. Methods: Patients undergoing total hip replacements for osteoarthritis between January 1, 2000 and December 31, 2013 in the four Nordic countries were studied. A total of 184,507 patients were stratified into 360 patient subcategories based on Country, age-group, sex, fixation, head size, and articulation. For each patient category, we determined the sample size needed from a single Country to obtain a more accurate and precise estimate of prosthesis-survival probability at 5 and 10 years compared to an estimate using data from all countries. The comparison was done using mean-square error. Results: We found large variations in the sample size needed, ranging from 40 to 2,060 hips, before an estimate from a single Nordic Country was more accurate and precise than estimates based on the NARA data. Conclusion: Using pooled survival-probability estimates for individual risk prediction may be imprecise if there is heterogeneity in the pooled data sources. By applying mean-square error, we demonstrate that for small sample sizes, applying the larger NARA database may provide a more accurate and precise estimate; however, this effect is not consistent and varies with the characteristics of the subcategory.
Stein Atle Lie - One of the best experts on this subject based on the ideXlab platform.
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homogeneity in prediction of survival probabilities for subcategories of hipprosthesis data the Nordic arthroplasty register association 2000 2013
Clinical Epidemiology, 2019Co-Authors: Christoffer Bartzjohannessen, Ove Furnes, Anne Marie Fenstad, Stein Atle Lie, Alma B Pedersen, Soren Overgaard, Johan KarrholmAbstract:Introduction: The four countries in the Nordic Arthroplasty Register Association (NARA) share geographic proximity, culture, and ethnicity. Pooling data from different sources in order to obtain higher precision and accuracy of survival-probability estimates is appealing. Nevertheless, survival probabilities of hip replacements vary between the countries. As such, risk prediction for individual patients within countries may be problematic if data are merged. In this study, our primary question was to address when data merging for estimating prosthesis survival in subcategories of patients is advantageous for survival prediction of individual patients, and at what sample sizes this may be advised. Methods: Patients undergoing total hip replacements for osteoarthritis between January 1, 2000 and December 31, 2013 in the four Nordic countries were studied. A total of 184,507 patients were stratified into 360 patient subcategories based on Country, age-group, sex, fixation, head size, and articulation. For each patient category, we determined the sample size needed from a single Country to obtain a more accurate and precise estimate of prosthesis-survival probability at 5 and 10 years compared to an estimate using data from all countries. The comparison was done using mean-square error. Results: We found large variations in the sample size needed, ranging from 40 to 2,060 hips, before an estimate from a single Nordic Country was more accurate and precise than estimates based on the NARA data. Conclusion: Using pooled survival-probability estimates for individual risk prediction may be imprecise if there is heterogeneity in the pooled data sources. By applying mean-square error, we demonstrate that for small sample sizes, applying the larger NARA database may provide a more accurate and precise estimate; however, this effect is not consistent and varies with the characteristics of the subcategory.
Ove Furnes - One of the best experts on this subject based on the ideXlab platform.
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homogeneity in prediction of survival probabilities for subcategories of hipprosthesis data the Nordic arthroplasty register association 2000 2013
Clinical Epidemiology, 2019Co-Authors: Christoffer Bartzjohannessen, Ove Furnes, Anne Marie Fenstad, Stein Atle Lie, Alma B Pedersen, Soren Overgaard, Johan KarrholmAbstract:Introduction: The four countries in the Nordic Arthroplasty Register Association (NARA) share geographic proximity, culture, and ethnicity. Pooling data from different sources in order to obtain higher precision and accuracy of survival-probability estimates is appealing. Nevertheless, survival probabilities of hip replacements vary between the countries. As such, risk prediction for individual patients within countries may be problematic if data are merged. In this study, our primary question was to address when data merging for estimating prosthesis survival in subcategories of patients is advantageous for survival prediction of individual patients, and at what sample sizes this may be advised. Methods: Patients undergoing total hip replacements for osteoarthritis between January 1, 2000 and December 31, 2013 in the four Nordic countries were studied. A total of 184,507 patients were stratified into 360 patient subcategories based on Country, age-group, sex, fixation, head size, and articulation. For each patient category, we determined the sample size needed from a single Country to obtain a more accurate and precise estimate of prosthesis-survival probability at 5 and 10 years compared to an estimate using data from all countries. The comparison was done using mean-square error. Results: We found large variations in the sample size needed, ranging from 40 to 2,060 hips, before an estimate from a single Nordic Country was more accurate and precise than estimates based on the NARA data. Conclusion: Using pooled survival-probability estimates for individual risk prediction may be imprecise if there is heterogeneity in the pooled data sources. By applying mean-square error, we demonstrate that for small sample sizes, applying the larger NARA database may provide a more accurate and precise estimate; however, this effect is not consistent and varies with the characteristics of the subcategory.
