Chronic diseases in the rubber industry.
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An overview is presented of epidemiologic studies of chronic diseases in the rubber industry. Analyses of the mortality experience during the period 1964-1972 of workers age 40-64 and retirees age 65-84 of two large rubber and tire manufacturing companies consistently disclosed excesses of deaths attributed to leukemia and lymphosarcoma, and for cancers of the stomach, large intestine, and prostate. The relation of site-specific malignancies to work histories and grouped occupational titles as surrogate measures of work-related exposures to possible carcinogens is described. There was no evidence of company-wide, sizable, consistent excess for the other major chronic diseases causes of death. Although a total cohort deficit in the mortality rate for lung cancer was found, there was a history of increased frequency of exposure to certain work areas among lung cancer decedents. Morbidity studies, including analysis of disability retirements, and ad hoc questionnaire and health testing surveys, disclosed excesses of chronic pulmonary diseases. There was evidence of an interactive effect in the association of work and smoking histories with pulmonary disability retirement. (+info)
Demographic variation in cancer in relation to industrial and environmental influence.
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Mortality data (183,064 deaths in a 30-year period, 1940-1969) by sex and three ethnic groups (white excluding Spanish-surnamed, nonwhite, and Spanish-surnamed) in 15 regions within the city (Houston), grouped around the air pollution sample collection stations have been analyzed. Valid contrast studies were possible in only one region within the city for all three groups and in six regions for white excluding Spanish-surnamed and nonwhite. There is evidence that the environmental factors of exposure over time to air and industrial pollutants in Houston has had a demonstrable effect in increasing regional mortality from cancer of the respiratory tract as well as from all other diseases and conditions of the respiratory tract and heart disease. This study points out the need for mutually sustained collaboration of effort of the scientific and industrial communities to redirect their attention and research efforts to the exploration of the carcinogenic potential of the microchemical environment. (+info)
Malignant tumors of the liver and lungs in an area with a PVC industry.
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The incidence of malignant tumors of the lung and bronchus and of cytologically confirmed primary malignant tumor of the liver was analyzed for a 4-yr period in a city with several factories, including a PVC industry. Prior to the study two cases of angio-sarcoma of the liver were diagnosed in workers employed in PVC production. The total incidence of analyzed tumors was only slightly higher than predicted. The tumors of the liver recorded did not show any dependence on place of work or residence. During the period of observation, malignant tumors of the bronchus (lung) were not recorded in the PVC industry. Their rate in the area in which the PVC industry is situated was approximately the same as that for the entire city area. The study does not indicate that the occurrence of malignant tumors other than angiosarcoma is associated with exposure to vinyl chloride. (+info)
Recent achievements and research initiated in the Swedish plastics and rubber industry.
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The improvement in exposure conditions in the Swedish vinyl chloride producing industry is reported. The article comments on the technology and control methods by which the vinyl chloride concentration has been lowered to less than 1 ppm vinyl chloride. Two epidemiological retrospective cohort studies are presently under way on workers in PVC-utilizing industries and in the rubber industry. (+info)
Priorities in the investigation of human health hazards in the plastics and synthetic rubber industries.
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Experiences in the past decade provide guidance in selecting priorities for investigation of health hazards in chemical industries. Pride of place should be given to the experience of large industrial populations, in part simply because large numbers of people are at risk and in part because such studies are more likely to give reliable answers. This recommendation has further strength when there is community exposure as well. Parenthetically, large populations provide opportunity to study multiple factor interaction; without this, toxic potential of a single agent may be obscured. Second, investigations should be mounted when there is reason for suspicion, as with particular chemical configurations, observed organ toxicity, animal carcinogenicity, unusual clinical experience ("signal" tumors). It may be added that when agents have already been used several decades, evaluation of human experience with them is now in order, if only to document absence of toxicity. The same recommendations hold for planned introduction of new agents or widened distribution of existing ones, until we have better information concerning validity of "pretesting" programs. Major advances have been made in epidemiological methods for these investigations. These now allow us to successfully focus on small defined groups as well as to manage large populations. (+info)
Techniques for assessment of teratologic effects: embryo culture.
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A simple method is described for growing rat embryos in vitro for 48 hr from head-fold to early limb-bud stages at rates of development and protein synthesis indistinguishable from those in vivo. Culture of the embryos can be continued for longer periods but at a reduced growth rate. Preheating the culture serum to 56 degrees C for 30 min improves embryonic development, but raising the culture temperature 2-3 degrees C or exposing the presomite embryos to 20% O2 (160 mm Hg) causes malformations, particularly of the brain and spinal cord. The value of such culture methods for teratology is briefly discussed. (+info)
Techniques for assessment of teratogenic effects: developmental enzyme patterns.
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Most studies designed for assessing teratogenic effects focus on only three of four types of final manifestations of abnormal development; namely intrauterine death, malformations, and growth retardation. Developmental toxicity evaluations generally do not include functional deficits. Current techniques are inadequate for assessing functional capability during perinatal development, and there is a need for improved measures. Thus, measurement of developmental enzyme patterns is proposed as an approach that directly evaluates acquisition of metabolic competence of fundamental organ systems. During ontogenesis most organs acquire their full complement of enzyme activities in a programmed sequence which corresponds to attainment of complete functional capability. The usual alterations in enzyme activity that characterize these patterns occur at one of three time periods, namely, late fetal, early neonatal, or late suckling. Qualitative or quantitative changes in these patterns at any time by one or more key enzymes of a tissue could be indicative of developmental toxicity. Factors are outlined relating to consideration of developmental enzyme profiles as indices of maturation capable of reflecting the action of toxic agents. This presentation: (1) reviews the current state of the art for evaluating effects on development, (2) considers the applicability of enzyme patterns for biochemical assessment of development, (3) characterizes the target tissues and those metabolic pathways and/or specific enzymes most sensitive and adaptable to practical toxicity evaluations, and (4) describes the steps being taken to validate this system. The ultimate objective of this approach is to determine whether alterations in developmental enzyme profiles will provide a technique with improved capability for assessing developmental toxicity. (+info)
Techniques for assessing teratogenic effects: epidemiology.
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Epidemiologic studies of malformations can aid in the understanding of human teratogenesis. Employing a variety of approaches epidemiology can develop or test hypotheses concerning possible causes or through surveillance provide data useful for a variety of purposes. Drawing heavily upon our experiences at the Center for Disease Control, this paper reviews some concepts and uses of epidemiology in studies of human teratogenesis. (+info)