Human exposure from dioxins in soil.

Dioxins are a family of chemical compounds that has received considerable attention, both historically and currently. This article reviews scientific field studies that examine the relationship between living on soil contaminated with dioxins and the level of dioxins in people's serum, with an emphasis on the University of Michigan Dioxin Exposure Study (UMDES), the largest and most comprehensive study of its kind. These studies conclude that the levels of dioxins in serum are most strongly correlated with age, gender, body mass index, weight loss, breast feeding, and smoking. Levels of dioxins in soil are not significant predictors for dioxin concentrations in serum. The increase in serum dioxin levels that is seen with age results from historic exposure and does not represent ongoing exposure. Based on the scientific field studies conducted to date, it appears that, in the absence of the consumption of contaminated animal products, there is little evidence of ongoing exposure from contaminated soil.

Statistical comparison of residential soil concentrations of PCDDs, PCDFs, and PCBs from two communities in Michigan.

The University of Michigan dioxin exposure study was undertaken to address concerns that the industrial discharge of dioxin-like compounds in the Midland, MI area had resulted in contamination of soils in the Tittabawassee River floodplain and downwind of the incinerator. The study was designed in a rigorously statistical manner comprising soil measurements of 29 polychlorinated dibenzo-p-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs), and polychlorinated biphenyls (PCBs) from 766 residential properties, selected probabilistically, in the Midland area and in Jackson and Calhoun Counties (Michigan) as a background comparison. A statistical comparison determined that the geometric mean toxic equivalent (TEQ) levels in samples from the target populations were statistically significantly above background. In addition, the probabilities of being above the 75th and 95th percentiles of background were also greater. Congener contributions to the TEQ were dominated by 2,3,4,7,8-PeCDF and 2,3,7,8-TCDF in the floodplain and by 2,3,7,8-TCDD in the incinerator plume. However, PCB 126 was the top congener contributing to the background TEQ. On the basis of statistical inference to the total population, it was estimated that about 36% of the properties in the floodplain and incinerator plume have at least one soil sample over the Michigan Department of Environmental Quality's soil direct contact criterion of 90 pg/g TEQ.

Characteristics of adolescents' sexual partners and their association with use of condoms and other contraceptive methods.

CONTEXT: While a number of studies have examined the association between individuals' characteristics and their contraceptive use, few studies have examined the influence of partners' characteristics on individuals' contraceptive use. METHODS: Using nationally representative data from the National Longitudinal Study of Adolescent Health, multiple logistic analyses were conducted to identify associations between the demographic characteristics of adolescents' heterosexual partners and adolescents' use of condoms or other contraceptive methods. RESULTS: The partners of white and black adolescents were likely to be similar to them, while the partners of Latino adolescents and of adolescents of "other" race or ethnicity were more likely to be of a different racial or ethnic group. Differences in age between adolescents and their partners were notable in all racial and ethnic groups. As adolescents age, the characteristics of their partners become more heterogeneous. The less similar adolescents and their partners are to one another--whether because of a difference in age, grade or school--the less likely adolescents are to use condoms and other contraceptive methods. CONCLUSIONS: Many adolescents have relationships with partners whose characteristics differ from theirs and with whom they are less likely to use condoms or other contraceptive methods. This behavior is more common as adolescents grow older. To provide appropriate counseling, sexuality educators and family planning providers need to consider the ways in which adolescents' relationships change as they age and discuss with them the dynamics of relationships involving partners who differ in age or other characteristics.

Socioeconomic disparities in health change in a longitudinal study of US adults: the role of health-risk behaviors.

This study investigated the hypothesis that socioeconomic differences in health status change can largely be explained by the higher prevalence of individual health-risk behaviors among those of lower socioeconomic position. Data were from the Americans' Changing Lives study, a longitudinal survey of 3,617 adults representative of the US non-institutionalized population in 1986. The authors examined associations between income and education in 1986, and physical functioning and self-rated health in 1994, adjusted for baseline health status, using a multinomial logistic regression framework that considered mortality and survey nonresponse as competing risks. Covariates included age, sex, race, cigarette smoking, alcohol consumption, physical activity, and Body Mass Index. Both income and education were strong predictors of poor health outcomes. The four health-risk behaviors under study statistically explained only a modest portion of the socioeconomic differences in health at follow-up. For example, after adjustment for baseline health status, those in the lowest income group at baseline had odds of moderate/severe functional impairment in 1994 of 2.11 (95% C.I.: 1.40, 3.20) in an unadjusted model and 1.89 (95% C.I.: 1.23, 2.89) in a model adjusted for health-risk behaviors. The results suggest that the higher prevalence of major health-risk behaviors among those in lower socioeconomic strata is not the dominant mediating mechanism that can explain socioeconomic disparities in health status among US adults.

Excess mortality among urban residents: how much, for whom, and why?

OBJECTIVES: The goals of this study were to estimate prospective mortality risks of city residence, specify how these risks vary by population subgroup, and explore possible explanations. METHODS: Data were derived from a probability sample of 3617 adults in the coterminous United States and analyzed via cross-tabular and Cox proportional hazards methods. RESULTS: After adjustment for baseline sociodemographic and health variables, city residents had a mortality hazard rate ratio of 1.62 (95% confidence interval [CI] = 1.21, 2.18) relative to rural/small-town residents; suburbanites had an intermediate but not significantly elevated hazard rate ratio. This urban mortality risk was significant among men (hazard rate ratio: 2.25), especially non-Black men, but not among women. Among Black men, and to some degree Black women, suburban residence carried the greatest risk. All risks were most evident for those younger than 65 years. CONCLUSIONS: The mortality risk of city residence, at least among men, rivals that of major psychosocial risk factors such as race, low income, smoking, and social isolation and merits comparable attention in research and policy.

Socioeconomic factors, health behaviors, and mortality: results from a nationally representative prospective study of US adults.

CONTEXT: A prominent hypothesis regarding social inequalities in mortality is that the elevated risk among the socioeconomically disadvantaged is largely due to the higher prevalence of health risk behaviors among those with lower levels of education and income. OBJECTIVE: To investigate the degree to which 4 behavioral risk factors (cigarette smoking, alcohol drinking, sedentary lifestyle, and relative body weight) explain the observed association between socioeconomic characteristics and all-cause mortality. DESIGN: Longitudinal survey study investigating the impact of education, income, and health behaviors on the risk of dying within the next 7.5 years. PARTICIPANTS: A nationally representative sample of 3617 adult women and men participating in the Americans' Changing Lives survey. MAIN OUTCOME MEASURE: All-cause mortality verified through the National Death Index and death certificate reviews. RESULTS: Educational differences in mortality were explained in full by the strong association between education and income. Controlling for age, sex, race, urbanicity, and education, the hazard rate ratio of mortality was 3.22 (95% confidence interval [CI], 2.01-5.16) for those in the lowest-income group and 2.34 (95% CI, 1.49-3.67) for those in the middle-income group. When health risk behaviors were considered, the risk of dying was still significantly elevated for the lowest-income group (hazard rate ratio, 2.77; 95% CI, 1.74-4.42) and the middle-income group (hazard rate ratio, 2.14; 95% CI, 1.38-3.25). CONCLUSION: Although reducing the prevalence of health risk behaviors in low-income populations is an important public health goal, socioeconomic differences in mortality are due to a wider array of factors and, therefore, would persist even with improved health behaviors among the disadvantaged.

Assessment of weighting methodology for the National Comorbidity Survey.

The authors studied weighting adjustments for the National Comorbidity Survey (1990-1992), a large-scale national epidemiologic investigation of the prevalence, risk factors, and consequences of psychiatric morbidity and comorbidity in the United States. Weighting adjustments for differential selection within households, new construction, unit nonresponse, and poststratification were examined separately and in combination. Specific issues addressed included the magnitude of the bias incurred from ignoring the weights, the added variance from weighting and how well this was predicted by simple formulae, and the performance of methods for trimming the weights. Weights had quite modest effects on point estimates of prevalences but resulted in major increases in variance unless trimmed. The weights after trimming and poststratification appeared to work well. It is suggested that the added variance from weighting be carefully monitored in similar surveys. Alternatives to the use of trimming for controlling variance are worth exploring.

Impact of nutrition education and mega-dose vitamin A supplementation on the health of children in Nepal.

The impact on vitamin A deficiency (VAD), wasting malnutrition, and excessive childhood mortality of two alternative approaches-nutrition education and mega-dose capsule distribution (6-12-month-olds: 100,000 IU; 1-5-year-olds: 200,000 IU)-in communities in Nepal are compared. Approximately 40,000 children from 75 locations in seven districts in two ecological settings (lowland and hills) took part in the study and were randomly allocated to intervention cohorts or a control group. At 24 months after the implementation of the project the reduction of risk for xerophthalmia was greater among children whose mothers were able to identify vitamin-A-rich foods (relative risk (RR) = 0.25; 95% confidence interval (CI) = 0.10-0.62) than among the children who received mega-dose capsules (RR = 0.59; 95% CI = 0.41-0.84). The risk of mortality at 2 years was reduced for both the nutrition education (RR = 0.64; 95% Cl = 0.48-0.86) and capsule distribution (RR = 0.57; 95% CI = 0.42-0.77) cohorts. The nutrition education programme was, however, more expensive to deliver than the capsule distribution programme. High rates of participation for children in the supplementation programme were achieved quickly. The nutrition education messages also spread rapidly throughout the study population (regardless of intervention cohort assignment). Practices, however, were slower to change. In communities where maternal literacy was low and channels of communication were limited the capsule distribution programme appeared to be more economical. However, there are economies of scale for nationwide education programmes that do not exist for capsule distribution programmes. Although nutrition education provides economies of scale and the promise of long-term sustainability, a comprehensive national programme requires both dietary supplementation and nutrition education components.

PIP: The effectiveness of two approaches to vitamin A deficiency prevention--nutrition education and mega-dose capsule distribution--was compared in a 3-year study involving almost 40,000 children 6 months to 10 years of age from seven ecologically diverse districts in Nepal. The nutrition education program promoted increased intake of vitamin A-rich foods during the dry season, serving wild greens, and primary health care service utilization. At baseline, 44.9% of the study villages did not have any cases of Bitot's spots; by the third year, 65.5% were free of this sign of vitamin A deficiency. 85% of community risk variation was explained by agricultural patterns, market food availability, household income, maternal literacy, sanitation, and the village's average nutritional status. At 12 months, capsule distribution had reduced the risk of new Bitot's spots by 55% (relative risk (RR), 0.45; 95% confidence interval (CI), 0.33-0.60); however, its impact had declined by 24 months and was non-significant at 36 months. At 24 months, the reduction of risk for xerophthalmia was greatest among children whose mothers were able to identify vitamin A-rich foods (RR, 0.25; 95% CI, 0.10-0.62) and were literate (RR, 0.06; 95% CI, 0.01-0.42). By 24 months, child mortality risk had declined in both the nutrition education (RR, 0.64; 95% CI, 0.48-0.86) and capsule distribution (RR, 0.57; 95% CI, 0.42-0.77) groups. Although the effects of both programs were similar, the capsule program achieved higher coverage rates at a lower cost while the educational intervention provided economies of scale and potential for long-term sustainability. Most feasible would be a comprehensive national program that included both these components as well as maternal literacy training.

Depression in black and white women. The role of marriage and socioeconomic status.

The degree to which the relationship between race and depression in US black and white women is modified by socioeconomic and marital status was investigated. Data on 534 black and 836 white women, 25 to 64 years old, obtained from the 1986 Americans' Changing Lives national survey were utilized. Depression was measured by the Centers for Epidemiologic Studies Depression scale. Poverty status and education were used as indicators of socioeconomic status (SES). For both black and white women, the prevalence of depression was higher among those with lower as compared to higher SES, and among the unmarried as compared to the married. The unstratified, age-adjusted odds of depression for black women was twice that for white women (odds ratio (OR) = 2.2; 95% confidence interval (CI), 1.7 to 2.8); however, when stratified by poverty status, race effects were observed for nonpoor (OR = 2.2; 95% CI, 1.6 to 3.0) but not for poor women (OR = 1.3; 95% CI, 0.7 to 2.1). Race effects were also more pronounced among married (OR = 2.0; 95% CI, 1.4 to 2.9) than unmarried women (OR = 1.6; 95% CI, 1.1 to 2.4). Controlling for known confounders did not alter these results. Additional analyses revealed that the black excess risk for depression was concentrated among higher SES, married women, with marital difficulties appearing to pay a major role in their elevated depression scores.

The social stratification of aging and health.

The way health varies with age is importantly stratified by socioeconomic status (SES)--specifically, education and income. Prior theory and cross-sectional data suggest that among higher SES persons the onset of health problems is usually postponed until rather late in life, while health declines are prevalent in lower SES groups by middle age. Thus, SES differences in health are small in early adulthood, but increase with age until relatively late in life, when they diminish due to selection or greater equalization of health risks and protections. The present paper strengthens our causal and interpretive understanding of these phenomena by showing: (1) that results previously reported for indices of SES hold separately for education and income; (2) that the interaction between age and SES (i.e., education or income) in predicting health can be substantially explained by the greater exposure of lower SES persons to a wide range of psychosocial risk factors to health, especially in middle and early old age, and, to a lesser degree, the greater impact of these risk factors on health with age; and (3) that results (1) and (2) generally hold in short-term longitudinal as well as in cross-sectional data. Implications for science and policy in the areas of aging, health, and social stratification are discussed.

HMO marketing and selection bias: are TEFRA HMOs skimming?

The research evidence indicates that health maintenance organizations (HMOs) participating in the Tax Equity and Fiscal Responsibility Act of 1982 (TEFRA) At-Risk Program tend to experience favorable selection. Although favorable selection might result from patient decisions, a common conjecture is that it can be induced by HMOs through their marketing activities. The purpose of this study is to examine the relationship between HMO marketing strategies and selection bias in TEFRA At-Risk HMOs. A purposive sample of 22 HMOs that were actively marketing their TEFRA programs was selected and data on organizational characteristics, market area characteristics, and HMO marketing decisions were collected. To measure selection bias in these HMOs, the functional health status of approximately 300 enrollees in each HMO was compared to that of 300 non-enrolling beneficiaries in the same area. Three dependent variables, reflecting selection bias at the mean, the low health tail, and the high health tail of the health status distribution were created. Weighted least squares regressions were then used to identify relationships between marketing elements and selection bias. Subject to the statistical limitations of the study, our conclusion is that it is doubtful that HMO marketing decisions are responsible for the prevalence of favorable selection in HMO enrollment. It also appears unlikely that HMOs were differentially targeting healthy and unhealthy segments of the Medicare market.

The cost effectiveness of strategies to reduce barriers to cataract surgery. The Operations Research Group.

The cost and effectiveness of eight approaches to reducing barriers to cataract surgery were evaluated in a rural area of South India during 1987-1989. The approaches were based on four intervention alternatives--aphakic motivator (AM), basic eye health worker (BW), screening van (SV), and mass media (MM). Each intervention was offered at two levels of economic incentive: partial, which provides free surgery and hospital stay, and full, which also provides transport from the recipient's village to the hospital and free food during the hospital stay. Evaluations took place in a probability selection of 90 villages, including ten control villages not subjected to either of the interventions. Only costs unique to patients from the intervention villages were considered: Health education and screening costs were included, surgery costs were not. Percentage reductions in the cataract blind backlog and increases in surgical coverage were used as effectiveness measures. Analyses suggest that the SV and AM interventions, both with full economic incentive, offer the greatest advantage. The AM intervention is the more effective of the two, but also the more costly.

Selection bias in TEFRA at-risk HMOs.

The issue of selection bias was investigated using data from 22 HMOs who are enrolling Medicare beneficiaries under Tax Equity and Fiscal Responsibility Act of 1982 (TEFRA) at-risk contracts. The study differs from previously published analyses of this issue in that it deals with the current Medicare risk program (TEFRA) rather than with earlier Demonstration Programs; as an indicator of selection bias, it utilizes beneficiary functional health status at enrollment; and it examines selection not only at the mean of the health status distribution, but at the two tails (very disabled, very able) as well. For each of the participating HMOs, the functional health status of recent Medicare enrollees was compared with that of a control group of randomly chosen fee-for-service beneficiaries. None of the HMOs experienced adverse selection, whether measured in terms of overall (mean) health status of enrollees or in terms of the proportion of the very disabled population that chose to join. Nine of the 22 HMOs were considered to have experienced favorable selection on the basis of the mean health status of new enrollees. In addition, ten more HMOs were found to have experienced favorable selection in one or both tails of the health status distribution. Although a specific cause for the observed enrollment patterns is not identified, speculation is made on factors that may or may not contribute. Evidence suggests that beneficiary self-selection is probably a more important explanation of these patterns than purposeful actions of HMOs to discourage enrollment by sicker beneficiaries (i.e., "skimming").

Social determinants of cataract surgery utilization in south India. The Operations Research Group.

A field trial was conducted to compare the effects of eight health education and economic incentive interventions on the awareness and acceptance of cataract surgery. Cataract screening and follow-up surgery were offered to more than 19,000 residents age 40 years and older in a probability sample of 90 villages in south India. Eight months after intervention, an evaluation was conducted to identify those in need of surgery who had been operated on. Two principal measures of program effectiveness are examined: awareness of cataract surgery and acceptance of the surgery. The type of intervention had a negligible effect on awareness of cataract surgery. A multiple logistic regression analysis revealed that individuals who were aware of surgery tended to be male, literate, and more affluent than those who were unaware of that option. Interventions that covered the complete costs of surgery had higher surgery acceptance rates. One health education strategy, house-to-house visits by a subject with aphakia, increased acceptance of the procedure more than others. In a multiple logistic regression analysis of acceptance rates, persons accepting surgery tended to be male; other factors were not important in explaining variation in acceptance rates.

Sampling the difficult-to-sample.

Difficult-to-sample populations are defined as rare populations or populations that are difficult to locate, enumerate or interview. This definition includes subgroups of the United States population that are at increased risk of adverse health effects associated with malnutrition. Examples include persons who are rare (pregnant women), difficult to locate (migrant farm workers), difficult to enumerate (homeless individuals) or difficult to interview (substance abusers). Probability methods to sample rare and elusive populations are reviewed briefly. Methods include disproportionately allocated sampling, multiplicity sampling and the use of multiple frames. The advantages and disadvantages of nonprobability sampling methods are compared using criteria typically applied to assess alternative probability sampling methods. The cost of data collection alone may prohibit consideration of probability sampling methods, but caution is urged before abandoning this statistically sound approach to sample selection. Considerations for sampling the difficult-to-sample are illustrated for one such population, the homeless.

Levels of disability among U.S. adults with arthritis.

This article studies the excess levels of disability experienced by persons with arthritis, compared to persons without the disease. The data set is the Supplement on Aging (1984 National Health Interview Survey); it has information for a national probability sample of community-dwelling persons ages 55 + (N = 16,148). (1) Arthritis people have more difficulty in physical functions, personal care, and household care than do nonarthritis persons. The excess disability is greatest for physical functions (walking, reaching, stooping, etc.). Disabled arthritis people have especially high degrees of difficulty in physical activities that require endurance and strength. (2) Various models are tested for walking, grasping, shopping, and light housework to show how comorbidity propels disability for arthritis people and to show arthritis' own contribution to disability in the presence of other chronic conditions. Difficulties escalate for arthritis people when they have other concurrent conditions. These models affirm that arthritis has a pronounced effect on physical dysfunctions, but these are not readily translated into personal and household care problems. Apparently, arthritis people often make successful accommodations so their roles and daily activities are not seriously affected by the disease.

Health care utilization and costs of adult cardiovascular conditions United States, 1980.

Cardiovascular conditions have a major economic as well as health impact on adults in the United States. In the National Medical Care Utilization and Expenditure Survey, conducted during 1980, health service data were obtained from a national sample of 17,123 civilian noninstitutionalized individuals. These data have been analyzed to define the impact and demographic patterns of health care utilization and costs attributable to adult cardiovascular conditions. Approximately 28 million persons in the United States, or 17.3 percent of the total civilian noninstitutionalized population 17 years of age and over, had a cardiovascular condition during 1980. Cardiovascular conditions were reported with increasing frequency in successively older age groups and were reported most frequently by black persons. The prevalence and economic impact differed by specific type of cardiovascular condition and whether the condition was complicated by another disease. To examine these differences, persons reporting cardiovascular conditions were categorized into four mutually exclusive groups: persons with hypertension alone, persons with arteriosclerotic cardiovascular and cerebrovascular disease associated with hypertension, persons with arteriosclerotic cardiovascular disease alone, and persons with cardiovascular disease associated with other conditions that might alter medical care utilization and disability. The disability, service utilization, and health care charges were compared among these groups, and data for each group were compared with those for the overall U.S. population. Survey participants were asked to rate their health relative to that of other people their age. The self-rating of persons reporting hypertension alone was lower than the national average. Only 17 percent of the general population rated their health as "fair" or "poor," but 27 percent of persons with hypertension alone used these descriptions. Overall, persons with hypertension alone were much less likely to be employed than the general population (52.2 percent versus 71.6 percent). However, when controlling for age, it was found that persons with hypertension alone were about as likely to be employed as the general population. On the average, persons with hypertension reported only slightly more work-loss days than did the general population (6.5 versus 4.9 days). A modest restriction of activity was reported by those with hypertension alone (20.1 days per year on the average compared with 15.6 for the general population). The mean number of ambulatory visits per year for those with hypertension alone was 7.9, only slightly greater than the 5.7 average for the overall population.(ABSTRACT TRUNCATED AT 400 WORDS)

Comorbidity and its impact on disability.

Older people often suffer from comorbidity, or several chronic conditions simultaneously. Disability rises rapidly as the number of chronic conditions grows, although very ill people who acquire another condition experience attenuated increases. High prevalence conditions such as arthritis tend to have a low or occasionally moderate impact for community residents, while low prevalence ones such as osteoporosis have a high impact; paired conditions sometimes give extra propulsion to disability, as when cerebrovascular disease and hip fracture co-occur. Further research is needed to pin-point combinations of conditions posing great risks and to identify demographic segments in which comorbidity has elevated effects.

Rapid epidemiologic assessment of cataract blindness. The Aravind Rapid Epidemiologic Assessment Staff.

A major constraint to obtaining reliable information about blindness and its causes in developing countries is the limited availability of ophthalmologists for diagnosis in population-based surveys. This study in rural south India assessed the feasibility of using non-ophthalmologists to make diagnoses in a population-based survey. Ten men in their early twenties with 12 years of schooling were recruited and trained as ophthalmic assistants through a six week course in basic ophthalmology. All people aged 40 and older in households in 24 villages were enumerated and invited to have an eye examination. At a central site, 1309 subjects were independently examined by an ophthalmologist and two different ophthalmic assistants. Ophthalmic assistant cataract diagnosis is both sensitive and specific relative to the ophthalmologist's diagnosis. Sensitivity and specificity estimates were used to adjust prevalence estimates obtained from ophthalmic assistant examinations conducted at the central site as well as at the doorstep of sample households. The findings indicate that epidemiologic assessment of cataract blindness can be completed using non-ophthalmologists to diagnose cataract.