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Biomedical subjects

T K Takaro

Publications and source records attributed to T K Takaro.

14 recordsLinked to original sources
PubMed2004

Comparison of local risk factors for children's atopic symptoms in Hanoi, Vietnam.

BACKGROUND: A 1999 study in Hanoi, Vietnam using the International Study on Asthma and Allergies in Childhood (ISAAC) questionnaire showed a high prevalence of atopic symptoms. Identifying risk factors for symptoms in these children may help in understanding the causes for these high estimates. METHODS: An ISAAC questionnaire with supplemental questions on environmental variables was distributed to 5495 school children in Hanoi and a suburban district, Dong Anh. The response rate was 65.7%. RESULTS: In Dong Anh, the following were among the significant age and gender adjusted associations: pig ownership [odds ratio (OR) (95% confidence interval), OR = 1.79 (1.18-2.70) for doctor-diagnosed asthma (DDA), OR = 1.72 (1.08-2.78) for doctor diagnosed hay fever (DDHF)] and farming [OR = 1.67 (1.27-2.19) for ever asthma, OR = 1.51 (1.09-2.09) for DDHF]. In multivariate models, tuberculosis (TB) was a significant predictor of atopic symptoms [Hanoi: OR = 3.09 (1.10-8.70) for DDA, Dong Anh: OR = 3.71 (1.40-9.84) for DDA, OR = 4.66 (1.88-11.57) for DDHF]. CONCLUSIONS: These findings are contrary to the "hygiene hypothesis". Recent immunologic and epidemiologic studies refute the inverse association between allergy and TB and may be one explanation for the positive association in this study. The positive association with pig ownership and farming may be because of exposures on farms in a developing country that may be different from exposures in farms of developed countries.

Adolescent↗
PubMed2001

Simultaneous analysis of surface marker expression and cell cycle progression in human peripheral blood mononuclear cells.

One method for examining cell cycle kinetics by flow cytometry uses continuous DNA labeling with bromodeoxyuridine (BrdU), a thymidine analogue. Upon incorporation into DNA, BrdU causes stoichiometric quenching of the DNA fluorochrome Hoechst 33258. After counterstaining with a secondary DNA fluorochrome (e.g., ethidium bromide), the analyst can distinguish cells in different phases of the cell cycle over a number of mitotic cycles with flow cytometry. In this report, we describe a modification of the flow cytometric BrdU-Hoechst assay that allows combined analysis of cell proliferation and immunophenotyping at the single cell level. To demonstrate an application of this method, human peripheral blood mononuclear cells were stimulated with tetanus toxoid or interleukin-2 for up to 6 days in the presence of BrdU, harvested, and immunostained for the cell surface markers CD3, CD4, CD8, CD14, CD19, and the cytokine receptor, CCR5. We used four-color flow cytometry analyses to simultaneously measure cell proliferation and surface marker expression, for the purpose of immunophenotyping and identifying specific cell subsets responding to antigen stimulation. Our successful application of this method suggests that it may be used to study immune responses at the molecular and cellular level and to identify mechanisms of immune system modulation.

Antigens, Differentiation, B-Lymphocyte↗
PubMed2000

Asthma and the home environment of low-income urban children: preliminary findings from the Seattle-King County healthy homes project.

OBJECTIVES: Childhood asthma is a growing public health concern in low-income urban communities. Indoor exposure to asthma triggers has emerged as an important cause of asthma exacerbations. We describe indoor environmental conditions related to asthma triggers among a low-income urban population in Seattle/King County, Washington, as well as caregiver knowledge and resources related to control of these triggers. METHODS: Data are obtained from in-person, structured, closed-end interviews with the caretakers of children aged 4-12 years with persistent asthma living in households with incomes less than 200% of poverty. Additional information is collected during a home inspection. The children and their caregivers are participants in the ongoing Seattle-King County Healthy Homes Project, a randomized controlled trial of an intervention to empower low-income families to reduce exposure to indoor asthma triggers. We report findings on the conditions of the homes prior to this intervention among the first 112 enrolled households. RESULTS: A smoker was present in 37.5% of homes. Mold was visible in 26.8% of homes, water damage was present in 18.6% of homes, and damp conditions occurred in 64.8% of households, while 39.6% of caregivers were aware that excessive moisture can increase exposures to allergens. Dust-trapping reservoirs were common; 76.8% of children's bedrooms had carpeting. Cockroach infestation in the past 3 months was reported by 23.4% of caregivers, while 57.1% were unaware of the association of roaches and asthma. Only 19.8% of the children had allergy-control mattress covers. CONCLUSIONS: Many low-income urban children with asthma in King County live in indoor environments that place them at substantial risk of ongoing exposure to asthma triggers. Substandard housing and lack of resources often underlie these exposures. Initiatives involving health educators, outreach workers, medical providers, health care insurers, housing agencies, and elected officials are needed to reduce these exposures.

Asthma↗
PubMed2000

Risk estimation and value-of-information analysis for three proposed genetic screening programs for chronic beryllium disease prevention.

Genetic differences (polymorphisms) among members of a population are thought to influence susceptibility to various environmental exposures. In practice, however, this information is rarely incorporated into quantitative risk assessment and risk management. We describe an analytic framework for predicting the risk reduction and value-of-information (VOI) resulting from specific risk management applications of genetic biomarkers, and we apply the framework to the example of occupational chronic beryllium disease (CBD), an immune-mediated pulmonary granulomatous disease. One described Human Leukocyte Antigen gene variant, HLA-DP beta 1*0201, contains a substitution of glutamate for lysine at position 69 that appears to have high sensitivity (approximately 94%) but low specificity (approximately 70%) with respect to CBD among individuals occupationally exposed to respirable beryllium. The expected postintervention CBD prevalence rates for using the genetic variant (1) as a required job placement screen, (2) as a medical screen for semiannual in place of annual lymphocyte proliferation testing, or (3) as a voluntary job placement screen are 0.08%, 0.8%, and 0.6%, respectively, in a hypothetical cohort with 1% baseline CBD prevalence. VOI analysis is used to examine the reduction in total social cost, calculated as the net value of disease reduction and financial expenditures, expected for proposed CBD intervention programs based on the genetic susceptibility test. For the example cohort, the expected net VOI per beryllium worker for genetically based testing and intervention is $13,000, $1,800, and $5,100, respectively, based on a health valuation of $1.45 million per CBD case avoided. VOI results for alternative CBD evaluations are also presented. Despite large parameter uncertainty, probabilistic analysis predicts generally positive utility for each of the three evaluated programs when avoidance of a CBD case is valued at $1 million or higher. Although the utility of a proposed risk management program may be evaluated solely in terms of risk reduction and financial costs, decisions about genetic testing and program implementation must also consider serious social, legal, and ethical factors.

Berylliosis↗
PubMed1999

Respiratory protective devices: rates of medical clearance and causes for work restrictions.

BACKGROUND: There are no published data on the outcomes and benefits of medical evaluations for the use of respiratory protective devices. We, therefore, conducted a retrospective database and chart review to assess the rates of medical clearance and causes for work restrictions at a Department of Energy complex. METHODS: All workers with work restrictions or denied clearance over a one-year period were identified and their medical records abstracted. RESULTS: Of the 5,569 workers who received medical evaluation, only 71 (1.3%) received limitations on respirator use documented in their medical record. Of the 65 workers with sufficient medical records for additional analysis, 9 of the 5,569 workers (0.2%) were denied medical clearance, while 56 workers (1.1%) received work restrictions. Pregnancy was the most common cause for denying medical clearance for respirator use. Lung disease, cardiovascular disease, and claustrophobia were the most common causes for work restrictions. Physical examination and spirometry added little to the detection of relevant medical conditions. CONCLUSIONS: We conclude that few workers fail medical clearance for respirator use or receive work restrictions. Data on adverse events from respirator use are needed to help design appropriate medical evaluations and uniform criteria for work restrictions or denial of medical clearance.

Adult↗
PubMed1999

Medical clearance for respirator use: sensitivity and specificity of a questionnaire.

BACKGROUND: OSHA regulations require that workers receive medical clearance prior to respirator use, and recently, a detailed questionnaire has been provided to assist with this purpose. However, there are limited published data on the sensitivity and specificity of self-administered questionnaires for identifying individuals who may safely wear a respirator. METHODS: We tested 474 consecutive workers at a Department of Energy complex. After completing the self-administered questionnaire, all workers received a standardized physician evaluation including interview, physical examination, and spirometry. The outcomes of the questionnaire assessment were compared to the outcomes of physician evaluation. RESULTS: Data for analysis were available from 413 of workers (87%). All workers received medical clearance; only 10 workers (2.4%) received work restrictions. The questionnaire demonstrated 100% sensitivity in identifying workers who required work restrictions, but had specificity of only 19%. Compared to physician evaluation, the questionnaire had modest sensitivity to the detection of chronic medical conditions. CONCLUSIONS: These data suggest that the rates of medical clearance for respirator use are very high, and that a self-administered questionnaire may be appropriate for medical clearance in certain settings. It is recommended that the policy of routine physician evaluation and spirometry for respirator clearance be re-examined.

Adult↗
PubMed1999

Structure and function of occupational health services within selected Department of Energy sites.

The mission of the United States Department of Energy sites has recently changed from nuclear weapons production to site remediation. Considering the mass of radiological and chemical contaminants at these sites, ensuring the health and safety of workers is a major challenge. This study used the findings from a written survey to describe occupational health services at 10 Department of Energy sites. The study aims were to describe and compare: (1) the primary hazards associated with the site activities; (2) the occupational safety and health structure, including service providers; and (3) the occupational health and safety functions, including surveillance, training, and service provision. Although explosions and radiological agents were identified as the hazards with the greatest associated risks, workers at these sites were most likely to be exposed to physical hazards, ergonomic hazards, and/or chemicals, including asbestos. Physicians accounted for 2.4% of service providers, nurses for 5.5%, industrial hygienists for 12.2%, safety personnel for 11.8%, and health physicists for 64.9%. It was concluded that there is an imbalance between the most important hazards and the types of health and safety personnel at these sites.

Delivery of Health Care↗
PubMed1999

A description of factors affecting hazardous waste workers' use of respiratory protective equipment.

This article describes the first phase of a study that was designed to gain an understanding of hazardous waste workers' attitudes and beliefs about the use of respiratory protective equipment. Exploratory, open-ended interviews were conducted among 28 respirator users at a US Department of Energy facility. Subjects were asked to describe their knowledge, attitudes, and beliefs about their risks to hazards at their worksites and to discuss their use of respiratory protective equipment. A detailed content analysis of the interviews resulted in the generation of a taxonomy of issues and concerns which fell into three general categories: 1) Knowledge, Beliefs, and Attitudes, 2) Physical and Psychological Effects, and 3) External Influences. Knowledge, Beliefs, and Attitudes included Training, Fit Testing, Medical Clearance, Work Exposures, Respirator Use, and Vulnerability to Disease. Physical and Psychological Effects included Somatic/Health Effects, Personal Comfort, Visual Effects, Fatigue, Communication, and Anxiety. External Influences included Structural Environment, Quality and Availability of Equipment, Other PPEs, Co-Worker Influence, Supervisor Influence, and Organizational Culture. The findings from this study have important implications to training and education programs. Effective respiratory protection programs depend on a knowledge of the factors that affect workers' use of equipment. This study suggests that efforts to assure equipment comfort and fit, to assist workers who see and hear less well as a result of their equipment, and to develop strategies to allay worker anxiety when wearing equipment should all be components of a program. An organizational culture that supports and abets the appropriate use of equipment is also a critical element in a successful program.

Adult↗
PubMed1998

Uncertainty analysis methods for comparing predictive models and biomarkers: A case study of dietary methyl mercury exposure.

Biologically based markers (biomarkers) are currently used to provide information on exposure, health effects, and individual susceptibility to chemical and radiological wastes. However, the development and validation of biomarkers are expensive and time consuming. To determine whether biomarker development and use offer potential improvements to risk models based on predictive relationships or assumed values, we explore the use of uncertainty analysis applied to exposure models for dietary methyl mercury intake. We compare exposure estimates based on self-reported fish intake and measured fish mercury concentrations with biomarker-based exposure estimates (i.e., hair or blood mercury concentrations) using a published data set covering 1 month of exposure. Such a comparison of exposure model predictions allowed estimation of bias and random error associated with each exposure model. From these analyses, both bias and random error were found to be important components of uncertainty regarding biomarker-based exposure estimates, while the diary-based exposure estimate was susceptible to bias. Application of the proposed methods to a simple case study demonstrates their utility in estimating the contribution of population variability and measurement error in specific applications of biomarkers to environmental exposure and risk assessment. Such analyses can guide risk analysts and managers in the appropriate validation, use, and interpretation of exposure biomarker information.

Animals↗
PubMed1981

Chromosomal location of structural genes encoding murine immunoglobulin lambda light chains. Genetics of murine lambda light chains.

To determine the chromosomal localization of murine lambda light (L) chain structural genes, DNA from a panel of 11 mouse x hamster somatic cell hybrids was scored for the presence of sequences homologous to cloned lambda DNA probe molecules. Six of the hybrids had detectable lambda I and lambda II gene sequences. In all six, the full complement of murine sequences was present, and in its germline configuration. The remaining hybrids lacked any detectable murine lambda L chain gene sequences. The only mouse chromosome present in all of the positive hybrids and absent from the negative ones was number 16, allowing the assignment of lambda L chain structural genes to this chromosome. Together with the previous assignments of the kappa L chain genes to chromosome 6 and heavy chain genes to chromosome 12, this finding completes the mapping of Ig structural genes in the mouse at the chromosomal level.

Animals↗
PubMedDate not supplied

An evaluation of factors affecting hazardous waste workers' use of respiratory protective equipment.

The purpose of this study was to describe the perceptions of a group of hazardous waste workers about their workplace hazards and to understand their beliefs and attitudes about the use of respiratory protective equipment (RPE). There were two phases of data collection: (1) interviews to identify factors that influence respirator use and (2) a written survey to evaluate the importance of these factors. This article describes the findings from the written survey completed by 255 eligible respondents (return rate = 46.5%, 255/548). Subjects used a weighting system to score 18 identified factors that influence the use of RPE. Scores were compared according to type of respirator, frequency of use, and associated health symptoms. The factors that had the most positive influence on respirator use were concern about work exposure, fit-testing, and training. The most negative influences were communication, personal comfort, effect on vision, structural environment, and fatigue. More frequent users (once per month or more) were significantly more likely to view fit-testing, health effects, and effects on vision negatively than were less frequent users. Persons who reported health symptoms associated with respirator use had more negative scores than persons without health symptoms. Workers categorized as laborers were more likely to be frequent respirator users and to wear supplied-air respirators, and were significantly more likely to view vulnerability to disease negatively, than were other worker groups. The findings from this study indicate that respiratory protection programs must extend beyond training and education; to be maximally effective, health professionals must be responsive to the specific concerns of the workers.

Adult↗
PubMedDate not supplied

Barriers and solutions in implementing occupational health and safety services at a large nuclear weapons facility.

The Hanford Nuclear Reservation is one of the U.S. Department of Energy's largest nuclear weapons sites. The enormous changes experienced by Hanford over the last several years, as its mission has shifted from weapons production to cleanup, has profoundly affected its occupational health and safety services. Innovative programs and new initiatives hold promise for a safer workplace for the thousands of workers at Hanford and other DOE sites. However, occupational health and safety professionals continue to face multiple organizational, economic, and cultural challenges. A major problem identified during this review was the lack of coordination of onsite services. Because each health and safety program operates independently (albeit with the guidance of the Richland field operations office), many services are duplicative and the health and safety system is fragmented. The fragmentation is compounded by the lack of centralized data repositories for demographic and exposure data. Innovative measures such as a questionnaire-driven Employee Job Task Analysis linked to medical examinations has allowed the site to move from the inefficient and potentially dangerous administrative medical monitoring assignment to defensible risk-based assignments and could serve as a framework for improving centralized data management and service delivery.

Contract Services↗
PubMedDate not supplied

Community-based survey of maquiladora workers in Tijuana and Tecate, Mexico.

Responses to a survey of 177 maquiladora workers by specially trained peers suggest that transnational corporations operating the plants are ignoring Mexican regulations regarding hazard communication, training, health and safety committees, and uncontrolled hazards in the workplace. The "global standard" for workplace health and safety, often claimed by transnationals, should be made a reality.

Adult↗