Biomedical subjects

Nalini Sathiakumar

Publications and source records attributed to Nalini Sathiakumar.

14 recordsLinked to original sources

PubMed2006

A follow-up study of women in the synthetic rubber industry: study methods.

BACKGROUND: Concerns about the possible toxic effects of workplace exposures in the synthetic rubber industry have centered on 1,3-butadiene (BD), styrene and dimethyldithiocarbamate (DMDTC). Our previous mortality studies of over 17,000 male synthetic rubber workers found an excess of leukemia that may be due to BD or BD plus other chemicals. Experimental studies have shown that BD produces mammary tumors in female mice and rats and ovarian tumors in female mice. AIM: This paper presents the methods of a follow-up study that evaluates the mortality experience of women employed in the North American synthetic rubber industry. METHODS: Women employed for at least 1 day at any of eight North American styrene-butadiene rubber plants were followed up from 1943 to 2002. Identifying and work history information were obtained from personnel records. Estimated quantitative exposure to BD, styrene and DMDTC, developed for our previous study of men, were used in this study. External analyses use the standardized mortality ratios (SMRs) to compare the cohort's cause-specific mortality rates to the rates of the female general population of the states or the province where the plants are located. Internal analyses use the Poisson regression and Cox proportional hazards models to examine specific cancer mortality rates in relation to BD, styrene and DMDTC exposure, by comparing an exposed cohort subgroup with the rate of unexposed cohort members.

Animals↗

PubMed2006

1,3-Butadiene and leukemia among synthetic rubber industry workers: exposure-response relationships.

Previous research updated the mortality experience of North American synthetic rubber industry workers during the period 1944-1998, determined if leukemia and other cancers were associated with several employment factors and carried out Poisson regression analysis to examine exposure-response associations between estimated exposure to 1,3-butadiene (BD) or other chemicals and cancer. The present study used Cox regression procedures to examine further the exposure-response relationship between several unlagged and lagged, continuous, time-dependent BD exposure indices (BD parts per million (ppm)-years, the total number of exposures to BD concentrations >100 ppm ("peaks") and average intensity of BD) and leukemia, lymphoid neoplasms and myeloid neoplasms. All three BD exposure indices were associated positively with leukemia. Using continuous, untransformed BD ppm-years the regression coefficient (beta) from an analysis that controlled only for age was 2.9 x 10(-4) (p<0.01); the regression coefficient adjusted for all covariates (age, year of birth, race, plant, years since hire and dimethyldithiocarbamate) was similar in magnitude (beta=3.0 x 10(-4), p=0.04). Lagging exposure had minimal impact on the results for leukemia for any of the three BD exposure indices. In models that controlled only for age, lymphoid neoplasms were associated with BD ppm-years and myeloid neoplasms, with BD peaks, but neither trend was statistically significant after adjusting for multiple covariates. The present results support the presence of a causal relationship between high cumulative exposure and high intensity of exposure to BD and leukemia.

Butadienes↗

PubMed2006

Evaluation of a school-based HIV/AIDS educational intervention in Ukraine.

PURPOSE: To assess changes observed in knowledge, attitudes toward people living with human immunodeficiency virus (HIV), self-efficacy and behavioral intentions of senior secondary school students after an HIV/AIDS (acquired immune deficiency syndrome) educational intervention in Vinnitsa, Ukraine. METHODS: A quasi-experimental, nonequivalent control group design with pretest-posttest components was employed. Two secondary schools (intervention and control) were randomly assigned to the study. A random sample of the 15-16-year-old students (100 participants in each school) completed anonymous self-reported pre- and postintervention questionnaires. In addition, a three-month follow-up questionnaire was administrated in both schools to assess the longevity of the intervention outcomes. Outcome scale scores were compared between the two groups on baseline, first, and second posttests separately. We used the Pearson chi-square test for categorical data and a t-test for difference in mean scores. RESULTS: After intervention we observed significantly higher knowledge, attitudes, and self-efficacy scores among students in the intervention school than in the control school (96.2 +/- 6.2 [SD] vs. 82.6 +/- 8.3, respectively, p < .01; 24.4 +/- 4.4 vs. 21.7 +/- 4.8, respectively, p < .01; 21.9 +/- 2.6 vs. 20 +/- 3.8, respectively, p < .01). As a result of the intervention, we also report significantly higher proportions of students in the intervention school than in the control school who would not intend to use alcohol and narcotics and who intend to use condoms (p < .01). CONCLUSIONS: Our AIDS education program was able to considerably improve students' knowledge, attitudes and self-efficacy, and promoted positive changes in participants' behavior intentions; it should therefore be extended to more schools to multiply its effects. However, in the context of evaluation, studies with actual HIV-risk behavior outcomes are urgent for Ukraine.

Acquired Immunodeficiency Syndrome↗

PubMed2006

Validation of 1,3-butadiene exposure estimates for workers at a synthetic rubber plant.

PURPOSE: This investigation assessed the validity of estimates of exposure to 1,3-butadiene (BD) developed for a plant included in a study of mortality among synthetic rubber industry workers. The estimates were developed without using historical measurement data and have not been validated previously. METHODS: Personal BD measurements came from an exposure-monitoring program initiated in 1977. For each job, we computed the year-specific difference between the BD estimate and the mean of BD measurements. We also computed rank correlation coefficients and calculated the mean, across all measurements, of the difference between the estimate and the measurement. RESULTS: The mean BD concentration was 5.2 ppm for 4978 measurements and 4.7 ppm for the corresponding estimates. The mean difference between estimates and measurements was -0.50 ppm (standard deviation, 26.5 ppm) overall and ranged from -227.9 to +27.0 ppm among all 306 job/year combinations. Estimates were correlated with measurements for all 306 combinations (rank correlation coefficient, r=0.45, p<0.0001), for 82 combinations pertaining to jobs that were well-defined by a specific set of tasks and typically found in styrene-BD rubber (SBR) plants (r=0.81, p<0.0001), for 70 combinations pertaining to jobs that were well-defined but not typical (r=0.29, p=0.01) and for 92 combinations pertaining to poorly-defined jobs typically found in SBR plants (r=0.56, <0.0001). Estimates were not correlated with measurements for poorly defined jobs not typically found in SBR plants (r=0.01, p=0.93). For well-defined typical SBR jobs with measurement means that were over 7.0 ppm, estimates were consistently lower than measurements. CONCLUSIONS: Possible reasons for differences between estimates and measurements included faulty assumptions used in developing BD estimates, unstable or nonrepresentive measurements and errors in linking measurement data to the job-exposure matrix. Exposure misclassification may have been more severe for subjects from the validation study plant than for subjects from other plants in the mortality study. BD estimates for typical SBR jobs, which comprise most operations at all but one of the plants in the mortality study, appeared to be useful for ranking workers by cumulative exposure. Uncertainty analyses would enhance the utility of the BD exposure estimates for quantitative risk assessment.

Butadienes↗

PubMed2006

Acute health effects of the Tasman Spirit oil spill on residents of Karachi, Pakistan.

BACKGROUND: On July 27 2003, a ship carrying crude oil ran aground near Karachi and after two weeks released 37,000 tons of its cargo into the sea. Oil on the coastal areas and fumes in air raised health concerns among people. We assessed the immediate health impact of oil spill from the tanker Tasman Spirit on residents of the affected coastline in Karachi, Pakistan. METHODS: We conducted a study consisting of an exposed group including adults living in houses on the affected shoreline and two control groups (A and B) who lived at the distance of 2 km and 20 km away from the sea, respectively. We selected households through systematic sampling and interviewed an adult male and female in each household about symptoms relating to eyes, respiratory tract, skin and nervous system, smoking, allergies, beliefs about the effect on their health and anxiety about the health effects. We used logistic regression procedures to model each symptom as an outcome and the exposure status as an independent variable while adjusting for confounders. We also used linear regression procedure to assess the relationship exposure status with symptoms score; calculated by summation of all symptoms. RESULTS: Overall 400 subjects were interviewed (exposed, n = 216; group A, n = 83; and group B, n = 101). The exposed group reported a higher occurrence of one or more symptoms compared to either of the control groups (exposed, 96% vs. group A, 70%, group B 85%; P < 0.001). Mean summary symptom scores were higher among the exposed group (14.5) than control group A (4.5) and control group B (3.8, P < 0.001). Logistic regression models indicated that there were statistically significant, moderate-to-strong associations (Prevalence ORs (POR) ranging from 2.3 to 37.0) between the exposed group and the symptoms. There was a trend of decreasing symptom-specific PORs with increase in distance from the spill site. Multiple linear regression model revealed strong relationship of exposure status with the symptoms score (beta = 8.24, 95% CI: 6.37-10.12). CONCLUSION: Results suggest that the occurrence of increased symptoms among the exposed group is more likely to be due to exposure to the crude oil spill.

Adolescent↗

PubMed2005

Methodologic issues in follow-up studies of cancer incidence among occupational groups in the United States.

PURPOSE: Incidence studies of occupational factors and cancer in the United States are problematic because the use of population-based registries to identify cases requires development of historical data on subjects' residences and often severely restricts the time period of follow up. This article describes procedures for addressing these challenges. METHODS: We used data from studies of cancer incidence and mortality among microelectronics industry employees to assess various methods for developing residential histories and the relative informativeness of the two studies. RESULTS: We developed residential histories for 98% of 99,229 mortality study subjects. Analyses making alternative assumptions about residential histories yielded standardized incidence ratios varying by at most 6%. Use of postemployment residential histories increased person-years by up to 62% and increased the observed number of cancers by up to 28%. The proportion of mortality study person-years included in the cancer incidence study ranged from 40% to 77% among work activity subcohorts. The number of observed cancer cases in the incidence study was 60% higher than the number of observed cancer deaths in the mortality study. CONCLUSIONS: Assumptions about residential history had little impact on validity. Use of information sources with national coverage to develop residential histories increased the incidence study's precision. Despite geographic and temporal restrictions, incidence studies provide more data than mortality studies on cancers with good survival. However, the potential for selection bias in incidence studies may vary considerably among subcohorts, indicating the need for cautious interpretation of such research.

Adult↗

PubMed2005

Chemical exposures in the synthetic rubber industry and lymphohematopoietic cancer mortality.

OBJECTIVE: This study evaluated the association between exposure to several chemicals and mortality from lymphohematopoietic cancer (LHC) among 16,579 synthetic rubber industry workers who were followed up from 1943 to 1998. METHODS: Poisson regression analyses examined LHC rates in relation to butadiene, styrene, and DMDTC exposure. Models provided maximum likelihood estimates of the relative rate for the contrast between categories of one agent, adjusting for other agents and for additional potential confounders. RESULTS: Cumulative exposure to 1,3-butadiene was associated positively with all leukemia (relative rates of 1.0, 1.4, 1.2, 2.9, and 3.7, respectively, for exposures of 0, >0 to <33.7, 33.7 to <184.7, 184.7 to <425.0, and 425.0+ ppm-years), chronic myelogenous leukemia and to a lesser extent with chronic lymphocytic leukemia. Adjusting for styrene and DMDTC attenuated these associations. After controlling for butadiene, neither styrene nor DMDTC displayed a consistent exposure-response trend with all leukemia, chronic myelogenous leukemia, or chronic lymphocytic leukemia. CONCLUSIONS: This study found a positive association between butadiene and leukemia that was not explained by exposure to other agents examined.

Adult↗

PubMed2005

Exposure assessment for retrospective follow-up studies of semiconductor- and storage device-manufacturing workers.

OBJECTIVE: This exposure assessment was conducted in the first large study of mortality and cancer incidence in semiconductor and storage device manufacturing. METHODS: Unique combinations of division, department and job codes and names (DDJ) from work history records were assigned to work groups and exposure categories. Agent exposure matrices assessed differences in potential exposures between groups. Changes in exposure over time were tracked by dividing the production history into manufacturing eras. RESULTS: Nineteen work groups were developed to capture 310,351 unique DDJs from 1965-1999. Agent exposure matrices contrasted exposure potential to solvents, metals, and work in cleanrooms between groups, and three manufacturing eras were identified for each site. CONCLUSIONS: The work groups, manufacturing eras and agent matrices have been used to classify workers in the study of cancer incidence and mortality.

Computer Storage Devices↗

PubMed2005

Styrene and ischemic heart disease mortality among synthetic rubber industry workers.

OBJECTIVE: We examined the relation between styrene and ischemic heart disease (IHD) mortality among 16,579 men in the synthetic rubber industry. METHODS: Associations were measured using stratified and multivariable analysis. RESULTS: Compared with workers with no exposure to styrene, men in the highest quintile of average intensity of exposure (5.50+ parts per million [ppm]) and in the highest quintile of cumulative exposure (60.67+ ppm-years) had IHD rate ratios of 1.14 (95% confidence interval [CI]=0.96-1.35) and 1.07 (95% CI=0.90-1.27), respectively. Acute IHD was not associated with average intensity of exposure within the most recent 2 years or with other indices of exposure. Chronic IHD rates were elevated in subjects with the highest exposure; these associations were weak and imprecise, and evidence of a positive exposure-response relation was limited. CONCLUSION: This study does not indicate that exposure to styrene causes fatal IHD.

Adult↗

PubMed2005

Mortality among semiconductor and storage device-manufacturing workers.

PROBLEM: We evaluated mortality during 1965 to 1999 among 126,836 workers at two semiconductor facilities and one storage device facility. METHOD: We compared employees' cause-specific mortality rates with general population rates and examined mortality patterns by facility, duration of employment, time since first employment, and work activity. RESULTS: Employees had lower-than-expected mortality overall (6579 observed deaths, standardized mortality ratio [SMR] = 65; 95% confidence interval [CI] = 64-67), for all cancers combined (2159 observed, SMR = 78, 95% CI = 75-81) and for other major diseases. Central nervous system cancer was associated with process equipment maintenance at one of the semiconductor facilities (10 observed, SMR = 247, 95% CI = 118-454). Prostate cancer was associated with facilities/laboratories at the storage device facility (18 observed, SMR = 198, (5% CI = 117-313). CONCLUSIONS: Further evaluation of workplace exposures or independent investigations of similar occupational groups may clarify the interpretation of associations observed in this study.

Adult↗

PubMed2003

Maternal mortality in Northern Nigeria: a population-based study.

OBJECTIVES: To determine the incidence and causes of maternal mortality as well as its temporal distribution over the last decade (1990-1999). STUDY DESIGN: All maternal deaths recorded within the study period in the State of Kano, Northern Nigeria, were analyzed. Maternal mortality ratios (MMR) were computed using the Poisson assumption to derive confidence intervals around the estimates. A non-linear regression model was fitted to obtain the best temporal trajectory for MMR across the decade of study. RESULTS: A total of 4154 maternal deaths occurred among 171,621 deliveries, yielding an MMR of 2420 deaths per 100,000. Eclampsia, ruptured uterus and anemia were responsible for about 50% of maternal deaths. CONCLUSION: We found one of the highest maternal mortality ratios in the world. Maternal mortality could be reduced by half at study site with effective interventions targeted to prevent deaths from eclampsia, ruptured uterus and anemia.

Anemia↗

PubMed2003

Mortality among triazine herbicide manufacturing workers.

Atrazine produces mammary gland cancer in one strain of rats and has been classified as an endocrine modulator. Epidemiologic studies have reported associations between agricultural use of atrazine and several forms of cancer. This study evaluated mortality patterns among workers at a plant that made atrazine and other triazine herbicides. The study covered the time period 1970-1997 and included 2213 people employed for at least 6 mo in operations related to the manufacture or formulation of atrazine and other triazine herbicides at a plant in Louisiana (LA). Vital status was determined for all but six subjects. Standardized mortality ratios (SMRs) with 95% confidence intervals (CIs) compared employees' mortality rates with those of the LA industrial corridor general population. Subjects had a total of 32,473 person-years of observation and a median of 15.8 yr since hire. There were 84 observed/118 expected deaths from all causes combined (SMR = 72, CI = 57-89) and 22/21 total cancer deaths (SMR = 106, CI = 66-160). Subjects had 4/1.1 deaths from non-Hodgkin's lymphoma (SMR = 372, CI = 101-952); this increase was not concentrated in the subgroup with long duration of employment and many years since hire. There were 6/4.8 (SMR = 124, CI = 46-271) digestive cancer and 7/6.3 (SMR = 112, CI = 45-230) lung cancer deaths. Data on other forms of cancer were sparse. This study was limited by its small size, by the relatively young age and short follow-up of its subjects, and by the lack of exposure data. It did not provide evidence that employment in triazine herbicide manufacturing and formulating operations was associated causally with overall or cause-specific mortality.

Adult↗

PubMed2002

Cancer incidence among triazine herbicide manufacturing workers.

This study evaluated cancer incidence and prostate specific antigen (PSA) testing among workers at a plant in Louisiana (LA) that made atrazine and other triazine herbicides. The study covered the time period 1985 through 1997 and included 2045 subjects, of whom 757 worked for the company that owned the plant and 1288 were contract employees. Linkage with a population-based cancer registry and review of death certificates and plant medical records identified cancer cases. Standardized incidence ratios (SIRs) with 95% confidence intervals (CIs) compared subjects' cancer incidence rates with those of a regional general population. Plant medical records provided data on the proportion receiving PSA tests among male company employees. Subjects had 46 observed and 40 expected cases of all cancers combined (SIR = 114, CI = 83-152) and had 11/6.3 prostate cancers (SIR = 175, CI = 87-312). The prostate cancer excess was greater in actively working company employees (5/1.3, SIR = 394, CI = 128-920) than in contract employees or inactive company employees (6/5.0, SIR = 119, CI = 44-260) and was limited to men under 60 years of age. Of the 11 prostate cancer cases, nine were diagnosed at an early clinical stage. From 1993 to 1999, the proportion of male company employees who had at least one PSA test was 86% for those who reached 40 years of age while actively working and was 98% for those who reached 45 years of age. The observed prostate cancer increase may have been due to the frequent PSA testing of actively working company employees. There is no epidemiologic or other information that clearly supports a causal relation between atrazine and prostate cancer.

Adult↗

PubMedDate not supplied

From conflict to collaboration, local political climate accelerates ITREOH's regionalization in South Asia.

As Pakistan becomes industrialized, the development of human resources is essential to addressing emerging health problems. The Fogarty International Center (FIC)-funded University of Alabama at Birmingham (UAB)-Aga Khan University (AKU) ITREOH initiative has been instrumental in filling the gaps in environmental and occupational health (EOH) training and research. Because of travel impediments to Pakistan, a regional short-term training program was implemented in Nepal and Sri Lanka. Workshop participants were from Pakistan, Nepal, Sri Lanka, India, and Bangladesh. The training programs enhanced north-to-south and south-to-south collaboration in research and training in South Asia. A major impact is the development of a certificate program in EOH at AKU. Research initiatives of regional and/or global concern are also under way in the other participating countries. The combination of face-to-face training with Web-based interaction for follow-up was optimal for short-term training.

Asia↗