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C E Ross

Publications and source records attributed to C E Ross.

At least 19 recordsLinked to original sources
PubMed1999

Monograph: reassessment of human cancer risk of aldrin/dieldrin.

In 1987, the US Environmental Protection Agency (EPA) classified aldrin and dieldrin as category B2 carcinogens, i.e. probable human carcinogens, based largely on the increase in liver tumors in mice fed either organochlorine insecticide. At that date, the relevant epidemiology was deemed inadequate to influence the cancer risk assessment. More time has now elapsed since early exposures of manufacturing workers to aldrin/dieldrin; therefore, updated epidemiological data possess more power to detect exposure-related differences in cancer risk and mortality. Also, recent experimental studies provide a plausible mode of action to explain the mouse specificity of dieldrin-induced hepatocarcinogenesis and call into question the relevance of this activity to human cancer risk. This monograph places this new information within the historic and current perspectives of human cancer risk assessment, including EPA's 1996 Proposed Guidelines for Carcinogen Risk Assessment. Updated epidemiological studies of manufacturing workers in which lifetime exposures to aldrin/dieldrin have been quantified do not indicate increased mortality or cancer risk. In fact, at the middle range of exposures, there is evidence of a decrease in both mortality from all causes and cancer. Recent experimental studies indicate that dieldrin-induced hepatocarcinogenesis in mice occurs through a nongenotoxic mode of action, in which the slow oxidative metabolism of dieldrin is accompanied by an increased production of reactive oxygen species, depletion of hepatic antioxidant defenses (particularly alpha-tocopherol), and peroxidation of liver lipids. Dieldrin-induced oxidative stress or its sequelae apparently result in modulation of gene expression that favors expansion of initiated mouse, but not rat, liver cells; thus, dieldrin acts as a nongenotoxic promoter/accelerator of background liver tumorigenesis in the mouse. Within the framework of EPA's Proposed Guidelines for Carcinogen Risk Assessment, it is proposed that the most appropriate cancer risk descriptor for aldrin/dieldrin, relating to the mouse liver tumor response, is 'not likely a human carcinogen', a descriptor consistent with the example of phenobarbital cited by EPA.

Aldrin↗
PubMed1999

Refining the association between education and health: the effects of quantity, credential, and selectivity.

We refine the established association between education and health by distinguishing three aspects of a person's education (quantity, credential, and selectivity) and by examining the mechanisms through which they may correlate with health. Data are from the 1995 Aging, Status, and the Sense of Control Survey, a representative U.S. national telephone survey of 2,593 respondents aged 18 to 95, with an oversample of elderly. Results show that physical functioning and perceived health increase significantly with years of formal education and with college selectivity for those with a bachelor's or higher degree, adjusting for age, sex, race, marital status, and parental education. The credential of a college degree has no net association with physical functioning and perceived health beyond the amount attributable to the additional years of schooling. Of the three aspects of education, years of schooling has the largest effect. Most of that association appears attributable to its correlation with work and economic conditions, social psychological resources, and health lifestyle. A large portion of the net association of college selectivity with physical functioning and perceived health appears attributable to health lifestyle.

Activities of Daily Living↗
PubMed1998

Medical surveillance for hematological disorders among active and retired oil refinery workers.

Ten-year (1985-1995) results of an expanded medical surveillance program of 2475 active employees and retirees of an oil refinery and petrochemical complex in Illinois are presented. At the end of the program, 116 participants with persistent abnormalities of complete blood cell count had been referred for hematologic evaluation, and most were found to have benign conditions. Fifteen of the 116 were referred for bone marrow and cytogenetic studies. All of the referred active employees (seven) were found to have completely normal bone marrows with no evidence of any myelopathic process. Among the eight retirees, two had normal bone marrows, one was diagnosed with Philadelphia chromosome-positive chronic myelogenous leukemia, one declined to participate, and four were diagnosed to have myelodysplastic syndrome (MDS) of various subtypes. A total of eight cases of MDS were identified, including six cases among program participants and two cases among nonparticipants. The MDS standardized incidence ratio of 1.26 (95% confidence interval = 0.54-2.47) was not statistically significant, and there was virtually no increase of MDS in persons less than 80 years of age (4 observed and 3.8 expected). This MDS increase was entirely from program participants, probably because of intensive follow-up and diagnostic screening. Routine surveillance of complete blood cell count information did not identify any new cases of leukemia or MDS in active employees. These findings suggest that the utility of expanded medical surveillance program in this population is very limited.

Adult↗
PubMed1998

Consequences of retirement activities for distress and the sense of personal control.

We compare retirement with full-time employment on four forms of engaging activity and examine the consequences of retirement activities for the sense of control and psychological distress. We use a 1995 U.S. national telephone probability sample of 2,592 respondents with an oversample of persons aged sixty and older. In comparison to the activities of full-time employees, those of retirees are more alienating on some aspects but more engaging on others. Retiree activities are more routine, provide less of a chance to learn new things, provide less positive social interaction with others, and they are especially unlikely to involve problem-solving. However, retirees' activities are also equally enjoyable and more autonomous compared to those of full-time workers. Autonomous activities, fulfilling activities which are enjoyable and provide the opportunity to learn new things, and integrated activities are all positively associated with a sense of control and negatively associated with psychological distress. However, solving problems is associated with both high levels of control and high levels of distress. Retirees have a significantly lower sense of control than do full-time employees, in large part because of the characteristics of their daily activities. At the same time, retirees do not have significantly higher levels of psychological distress.

Adult↗
PubMed1997

A mortality study of oil refinery and petrochemical employees.

Results from a prospective mortality surveillance of 3803 refinery and petrochemical workers at a Shell Oil Company facility in Louisiana are presented. This report includes employees who worked more than 6 months before January 1, 1994 and pensioners who were alive as of January 1, 1973. Vital status was ascertained through 1993. Regardless of the comparison population used to calculate expected numbers (United States, Louisiana, or the surrounding tri-parish area), significantly fewer deaths were observed for all causes combined, all malignant neoplasms, heart disease, nonmalignant respiratory disease, and cirrhosis of the liver among male employees after 10 or more years' latency. With the United States as comparison, the all causes combined standardized mortality ratio (SMR) was 0.72 (95% confidence interval [CI] = 0.65 to 0.79), and the SMR for all cancer was 0.75 (95% CI = 0.61 to 0.92). The brain cancer rate for this group was nonsignificantly increased, with five observed deaths and three expected deaths, whereas mortality from leukemia was consistently lower than expected. The overall favorable mortality experienced by employees at this refinery and chemical plant is probably a result of a combination of factors, such as the healthy worker effect, relatively low risks related to the workplace, and the beneficial effects of continuing employment.

Adult↗
PubMed1997

Illness absence at an oil refinery and petrochemical plant.

Results from a prospective illness-absence surveillance of refinery and petrochemical workers from 1986 through 1994 are presented. Illness absence data for this study were extracted from the morbidity section of the Shell Oil Company's Health Surveillance System, which includes records of all illness absences in excess of 5 days. The majority of employees (59%) had no illness absence during the 9-year period studied. The 13% of the population who had three or more absences accounted for 63% of the total illness absence episodes and 62% of the total work days lost. Frequency rate and duration of absence increased with increasing age. The increased illness absence was associated with the presence of known health risk factors, such as smoking, elevated blood pressure, high cholesterol, and obesity. For example, obese women had a twofold increased illness absence rate compared with nonobese women and the rate for male smokers doubled that of nonsmoking men. These health risk factors are also more common among employees with three or more absences than those with fewer or no absences. The goal of this analysis is to quantify the impact of illness absence to develop disease prevention strategies to maximize good health in employees and to minimize both the frequency and duration of illness absence.

Absenteeism↗
PubMed1997

Education and the subjective quality of life.

We examine whether education influences subjective quality of life. If it does, what are the mechanisms by which education affects well-being? We propose that education improves well-being because it increases access to nonalienated paid work and economic resources that increase the sense of control over life, as well as access to stable social relationships, especially marriage, that increase social support. We examine the relationship between education and a variety of indicators of subjective quality of life-depression, anxiety, anger, aches and pains, malaise, and dissatisfaction. Using two representative national samples collected in 1990 and 1995, we find that the well educated have lower levels of emotional distress (including depression, anxiety, and anger) and physical distress (including aches and pains and malaise), but they do not have lower levels of dissatisfaction. Education reduces distress largely by way of paid work, nonalienated work, and economic resources, which are associated with high personal control; but the extent to which it reduces distress by way of marriage and social support is much more modest. We contrast distress and dissatisfaction as indicators of the subjective quality of life.

Adult↗
PubMed1996

Identification of a potential role for the adventitia in vascular lesion formation after balloon overstretch injury of porcine coronary arteries.

BACKGROUND: In the present series of experiments, we examined the onset of cell proliferation and growth factor expression after balloon overstretch injury to porcine coronary arteries. METHODS AND RESULTS: Domestic juvenile swine underwent balloon overstretch injury to the left anterior descending and circumflex coronary arteries with standard percutaneous transluminal coronary angioplasty balloon catheters. To identify proliferating cells, 5-bromo-2-deoxyuridine (BrDU) was administered over a period of 24 hours before the animals were killed at either 1, 3, 7, or 14 days after injury. Immunohistochemistry was performed with monoclonal antibodies to BrDU and smooth muscle cell markers. Three days after injury, a large number of proliferating cells were located in the adventitia, with significantly fewer positive cells found in the media and lumen. Seven days after injury, proliferating cells were found primarily in the neointima, extending along the luminal surface. In situ hybridization for PDGF A-chain and beta-receptor mRNAs revealed that the expression of these two genes was closely correlated with the sites of proliferation at each time point. Studies in which BrDU was injected between days 2 and 3 and the animals were killed on day 14 suggested that the proliferating adventitial cells may migrate into the neointima. CONCLUSIONS: These data suggest that adventitial myofibroblasts contribute to the process of vascular lesion formation by proliferating, synthesizing growth factors, and possibly migrating into the neointima. Increased synthesis of alpha-smooth muscle actin observed in the adventitial cells after arterial injury may constrict the injured vessel and contribute to the process of arterial remodeling and late lumen loss after angioplasty.

Animals↗
PubMed1996

Long-term follow-up mortality study of petroleum refinery and chemical plant employees.

A previous report presented the 1948-1983 mortality patterns of the Shell Deer Park Manufacturing Complex employees who were employed for at least 3 months from 1948 through 1972. The present study updates the earlier investigation by extending the vital status follow-up through 1989 and by expanding the cohort to include employees hired after 1972. As in the previous study, the overall mortality and cancer mortality for both refinery and chemical employees were quite favorable compared to residents in the local population. Among refinery workers, cancers for which a suspicion of work-relatedness was raised in the previous study, i.e. leukemia and cancers of the central nervous system and biliary passage/liver, no supportive evidence was found in this update. For both refinery and chemical plant employees, the mortality rate due to cancers of all lymphopoietic tissue increased with increasing duration of employment; this finding was also noted by the original study. This was also evident for lymphoreticulosarcoma in refinery employees and for leukemia in chemical plant employees. However, elevations of cancers of all lymphatic and hematopoietic tissue are primarily confined to employees who started work at the complex before 1946. By contrast, deaths from cancer of all lymphatic and hematopoietic tissue for employees hired after 1945 were 22% lower than the comparison population. Seven deaths with mesothelioma mentioned on the death certificates were identified, with 3.2 deaths expected, resulting in a statistically nonsignificant SMR of 219.

Adult↗
PubMed1996

Mortality among maintenance employees potentially exposed to asbestos in a refinery and petrochemical plant.

This paper reports the mortality experience from 1948 to 1989 of 2,504 maintenance employees who had a minimum of one year of employment in jobs with potential exposure to asbestos at a Texas refinery and petrochemical plant. For the purposes of this study, "potential exposure" is equated with those jobs or crafts having the greatest direct potential proximity to, or which worked directly with, asbestos-containing materials, especially asbestos-containing thermal insulation. Approximately one-half of the study population had 10 years or longer potential exposure, and 80% had their first potential exposure before 1970. The total population exhibited significantly lower mortality for all causes, the standardized mortality ratio (SMR = 77); and for all cancer (SMR = 85), as compared to residents in the surrounding communities. Statistically significant deficits in mortality were also observed in a number of noncancerous diseases such as heart disease (SMR = 78; 95% CI = 69-88), nonmalignant respiratory disease (SMR = 70; 95% CI = 50-95), and cirrhosis of the liver (SMR = 44; 95% CI = 22-79). Mortality among employees who had 20 years or longer since their first potential exposure was also examined; the pattern of mortality was similar to that exhibited by the total cohort, with a slight increase in the SMR for most of the causes. The only statistically significant excess of mortality found was a fourfold increase in mesothelioma (5 observed and 1.2 expected deaths) the SMR was 428 (95% CI = 139-996) for the total cohort and was 469 (95% CI = 152-1093) for those who had 20 years or more since first potential exposure. In contrast to asbestos industry worker studies, mortality for lung cancer was substantially lower than the general population (SMR = 81; 95% CI = 63-103). The observed number of deaths for cancer of the larynx was virtually the same as expected (3 observed vs. 2.8 expected). This study also showed decreased mortality for cancers of gastrointestinal organs such as the esophagus (SMR = 78), stomach (SMR = 63), large intestine (SMR = 91), rectum (SMR = 55), or pancreas (SMR = 90)--cancers that have been reported to be elevated in studies of various industry workers directly exposed to asbestos.

Adult↗
PubMed1996

Characteristics of cancer cell death after exposure to cytotoxic drugs in vitro.

The characteristics of cell death were investigated after exposure of CCRF-CEM.f2 cells to five drugs over a broad concentration range; these were the glucocorticoid dexamethasone (DXM), the mitotic inhibitor vincristine (VIN) and three antimetabolites, methotrexate (MTX), 5'-fluoro-2'-deoxyuridine (FUdR) and 5'-fluorouracil (5-FU). Drug-treated cells were monitored for cell death mechanisms at different times by examining the pattern of DNA degradation, cell morphology and flow cytometric profile, together with effects on cell growth over 72 h. At growth-inhibitory drug concentrations, the first changes were cell cycle perturbations detectable after 4-6 h of drug exposure. The appearance of features characteristic of apoptotic cell death was noted after all drug treatments in the CCRF-CEM.f2 cell line, but the pattern and kinetics varied considerably. VIN induced apoptotic changes by 12 h, while DXM treatment caused apoptosis only after 48 h. Both MTX and FUdR induced morphological changes characteristic of apoptosis at least 24 h before internucleosomal DNA cleavage, which was detectable only after 48 h. In contrast, 5-FU did not cause internucleosomal DNA cleavage by 48 h at any concentration, despite the presence of morphologically apoptotic cells 24 h earlier. These data suggest that disruption of the cell cycle caused by drug treatment may be the common trigger initiating the drug-specific apoptotic sequence of dying cells.

Antineoplastic Agents↗
PubMed1996

Fundamental analysis in research on well-being: distress and the sense of control.

Fundamental analysis defines the basic terms of social and behavioral research. It usually follows the rule "one concept to a measure." However, some responses inherently reflect more than one underlying attribute, as when a test score reflects both knowledge of the subject and practice with taking tests. The standard methods of fundamental analysis break down in the presence of such cross-cutting factors. In this article, we discuss two instances of confusion and disagreement among social and behavioral scientists generated by the effects of cross-cutting factors on critical measures. In the first instance, a tendency to agree with the statements of others can make beliefs about personal control over events and outcomes seem unrelated to beliefs about control by chance, fate, or powerful others. The tendency to agree correlates positively with age. In the second instance, emotional expressiveness can make the frequency or intensity of sadness seem unrelated to the frequency or intensity of happiness. Women, who make up the large majority of older Americans, express themselves more freely than men. The apparent disjointedness of internal and external attributions of control, or of positive and negative emotions, results from methods assuming that the response to each question reflects one and only one underlying factor. Cross-cutting factor models eliminate the bias and confusion produced by response tendencies and help isolate and define the essential dimensions of response.

Aged↗
PubMed1996

Mortality study of employees with potential exposure to epichlorohydrin: a 10 year update.

OBJECTIVES: A 10 year extension of follow up (up to 1993) of 863 employees who had potential exposure to epichlorohydrin at two chemical plants between May 1948 and December 1965 was conducted to further evaluate the previously reported potential association between exposure to epichlorohydrin and heart disease. METHODS: The mortality observed was compared with that expected from the death rates from the local male population where these chemical plants are located. Workers were assigned to one of five exposure categories based on their job with the highest level of potential exposure. Vital status was ascertained to the end of 1993. RESULTS: Among diseases of particular interest, there were no excess deaths from heart disease (standardised mortality ratio (SMR) 63.3), lung cancer (SMR 63.8), or non-malignant respiratory disease (SMR 37.7) for employees with 20 or more years after first exposure. Based on the level of potential exposure to epichlorohydrin, mortality for heart disease was slightly higher (SMR 75.7, 95% confidence interval (95% CI) 51.8-106.7) in the moderate to heavy exposure group than in the none to light exposure group (SMR 59.5, 95% CI 37.7-89.3); this difference is well within the range of random variation. The SMR for heart disease was 90.4 among employees who had both probable exposure to allyl chloride and moderate to heavy exposure to epichlorohydrin, although it was 88.1 among employees who had moderate to heavy potential exposure to epichlorohydrin but no exposure to allyl chloride. CONCLUSIONS: This study does not support an association between exposure to epichlorohydrin and heart disease or lung cancer. There were no additional deaths from leukaemia in this update; the raised SMR for leukaemia noted in the previous study has substantially decreased from 500.0 to 161.3 (95% CI 33.2-471.0) and is not significant. The overall mortality and cancer mortality of employees potentially exposed to epichlorohydrin continued to be lower than that of the local population.

Adult↗
PubMed1996

A novel DNA repair response is induced in human cells exposed to ionizing radiation at the G1/S-phase border.

We have discovered a novel DNA repair response which is induced in cells irradiated with gamma rays at the G1/S-phase border. The induction of this repair response occurs at a stage in the cell cycle when overall levels of excision repair are reduced compared to cells irradiated in either S phase, G2/M phase or exponential growth. The induced repair is characterized by the formation of very long excision repair patches (VLERP) containing at least 150 nucleotides compared to the constitutive repair patches that are 3-5 nucleotides. These VLERP appear to be produced in response to a DNA lesion specific to ionizing radiation since they were not observed in cells irradiated with UV radiation at G1/S phase. The formation of VLERP requires both the nucleotide excision repair pathway, since they are absent in irradiated xeroderma pigmentosum group A cells, and the synthesis of new protein and mRNA. The time course for the induction of the VLERP shows an initial delay of 2 h, followed by a steady increase for up to 12 h after irradiation. By comparison, the production of the constitutive short repair patches shows an initial rapid production which levels out after 4 h.

Cells, Cultured↗
PubMed1996

Education, age, and the cumulative advantage in health.

The positive association between educational attainment and health is well established, but the way in which the education-based gap in health varies with age is not. Do the health advantages of high educational attainment and disadvantages of low educational attainment diverge or converge with age? The cumulative advantage perspective predicts a diverging SES gap in health with age, but past evidence does not allow us to accept or reject the hypothesis. We address this issue in two samples, cross-sectionally and over time, with three health measures. The first data set consists of a 1990 telephone interview of a national probability sample of U.S. households. There are 2,031 respondents, aged 18 to 90. The second is a national probability sample of U.S. households in which 2,436 respondents aged 20 to 64 were interviewed by telephone in 1979 and reinterviewed in 1980. We find that the gap in self-reported health, in physical functioning, and in physical well-being among people with high and low educational attainment increases with age. The health advantage of the well educated is larger in older age groups than in younger. Health advantages of high income and disadvantages of low income also diverge with age, but household income does not explain education's positive effect.

Activities of Daily Living↗
PubMed1995

Have sperm counts been reduced 50 percent in 50 years? A statistical model revisited.

OBJECTIVE: To reanalyze data that were used in a linear model to predict that mean sperm counts have been reduced globally by approximately 50% in the last 50 years. DESIGN: The mean sperm counts and their temporal distribution were reanalyzed via several different statistical models (quadratic, spline fit, and stairstep). CONCLUSION: There are several reasons why a published linear regression model is inappropriate to infer a 50% reduction in mean sperm counts in the last 50 years. These include [1] the potential selection biases that may have occurred with the 61 assembled studies such that they are not representative of their underlying populations; [2] the likely variability in collection methods, in particular, the lack of adherence to a minimum prescribed abstinence period, as has been stated for the largest study, which contained 29.7% of all the subjects included in the analysis; [3] the paucity of data in the first 30 years of the 50-year trend analysis; [4] the fact that if the last 20 years of data are examined, which contains 78.7% of all the studies and 88.1% of the total number of subjects, there is no decrease in sperm counts, in fact, sperm counts were observed to have increased; [5] the conflicting data from a large individual laboratory, which was not prone to the collection variability that likely occurred between the 61 studies, that did not suggest a decline in mean sperm count or seminal volume during a comparable time period, even though this laboratory published the data that were largely responsible for the high historical values in the linear model; and, most importantly, [6] the variety of other mathematical models that perform statistically better at describing the recent data than the linear model and thus offer substantially different hypotheses. The data are only robust during the last 20 years of the analysis, in which all the models, except the linear model, suggest constant or slightly increasing sperm counts.

Female↗
PubMed1995

Does employment affect health?

Employment correlates positively with health, but is employment cause or consequence? The social causation hypothesis says that employment improves the health of men and women. The selection hypothesis says that healthy people get and keep jobs more than unhealthy people do. We test both hypotheses using longitudinal data from a national probability sample (N = 2,436 interviewed in both years). In the equations representing social causation, full-time employment predicts slower declines in perceived health and in physical functioning for both men and women. Full-time employment has the same effect for both sexes. Among women, it also has the same effect for White and non-White, and for married and nonmarried. In the equations representing social selection, physical functioning increases the odds of getting or keeping a full-time job for both sexes. Perceived health increases the odds for women but not for men. In regard to homemaking among women, homemaking predicts significantly greater declines in health, but health has no effect on the odds of becoming or staying a homemaker.

Adult↗