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PubMed1990

Sex differentials in premature death among professionals. Part II.

[The author] "explores two hypotheses proposed to explain a reversal of the sex differential in mortality which appears in the 1968-72 death rates of Wisconsin [United States] professionals. The first hypothesis proposes that the observed effect is attributable to differentials in the distribution of behavioural risk factors for leading cause of death....The second hypothesis posits that the effect may be due to differentials in occupational variables which have systematic gender-divergent outcomes. Occupational levels, tasks, environments and careers all have the potential for such effects. The overall conclusion of the study is that health is systematically related to the quality of support and other conditions in the two major micro-environments for living: work and home."

Americas↗

PubMed1994

Family structure, residential mobility, and school dropout: a research note.

This paper examines the hypothesis that high levels of residential mobility among nonintact families account for part of the well-known association between living in a nonintact family and dropping out of high school. Children from single-parent families and stepfamilies are more likely than children from two-parent families to move during the school year. As much as 30% of the difference in the risk of dropping out between children from stepfamilies and children from intact families can be explained by differences in residential mobility. Previously, mechanisms explaining school failure on the part of children in nonintact families were more plausible for children in single-parent families than for children in stepfamilies; high levels of residential mobility apply to both groups of children. In addition, residential mobility lends itself to manipulation by public policy, with potentially remedial effects for vulnerable children.

Adolescent↗

PubMed1994

[Epilepsy in adults and elderly subjects. Epidemiological aspects, therapeutic strategies].

The important and quite amazing increase in frequency of epileptic seizures and epilepsy in patients older than 60 years is now recognized as a valid epidemiologic phenomenon. This has been emphasized in the last epidemiologic studies performed with an identical methodology in our industrialized countries. This could in part be explained by the growth of the aged population, by the ageing itself and by a larger exposition to the various risk factors existing at this age. The first is represented by cerebrovascular diseases, but cerebral involution--per se--is surely involved. Prescription of antiepileptic drugs in these patients has to be adapted to the individual cautiously. Pharmacokinetics and pharmacodynamic variations are more frequent than in other populations. On the other hand, drug interactions seem to be more frequent and severe because of the polytherapy prescribed for multiple other diseases. Intellectual or sensorial decline may explain the imperfect compliance observed in these patients.

Adult↗

PubMed2002

Assessing human health response in life cycle assessment using ED10s and DALYs: part 2--Noncancer effects.

In Part 1 of this article we developed an approach for the calculation of cancer effect measures for life cycle assessment (LCA). In this article, we propose and evaluate the method for the screening of noncancer toxicological health effects. This approach draws on the noncancer health risk assessment concept of benchmark dose, while noting important differences with regulatory applications in the objectives of an LCA study. We adopt the centraltendency estimate of the toxicological effect dose inducing a 10% response over background, ED10, to provide a consistent point of departure for default linear low-dose response estimates (betaED10). This explicit estimation of low-dose risks, while necessary in LCA, is in marked contrast to many traditional procedures for noncancer assessments. For pragmatic reasons, mechanistic thresholds and nonlinear low-dose response curves were not implemented in the presented framework. In essence, for the comparative needs of LCA, we propose that one initially screens alternative activities or products on the degree to which the associated chemical emissions erode their margins of exposure, which may or may not be manifested as increases in disease incidence. We illustrate the method here by deriving the betaED10 slope factors from bioassay data for 12 chemicals and outline some of the possibilities for extrapolation from other more readily available measures, such as the no observable adverse effect levels (NOAEL), avoiding uncertainty factors that lead to inconsistent degrees of conservatism from chemical to chemical. These extrapolations facilitated the initial calculation of slope factors for an additional 403 compounds; ranging from 10(-6) to 10(3) (risk per mg/kg-day dose). The potential consequences of the effects are taken into account in a preliminary approach by combining the betaED10 with the severity measure disability adjusted life years (DALY), providing a screening-level estimate of the potential consequences associated with exposures, integrated over time and space, to a given mass of chemical released into the environment for use in LCA.

Dose-Response Relationship, Drug↗

PubMed1991

[Estimate of the population at risk between 2 census records for the calculation of incidence level or mortality of cancer: comparison of 4 methods].

The estimation of incidence (or mortality) rates for a given disease in a defined population needs precise knowledge of the population at risk of contracting the disease (or dying) during the study period. This article proposes and compares four methods for estimating population by age between two census surveys. The three methods which consist in aging the generations give results which are extremely close for age specific and standardized rates; on the contrary, the methods which do not take into account the generations at birth are inadequate due to the lack of births during the two world wars.

Adult↗

PubMed1985

Epidemiology of multiple sclerosis in US veterans: III. Migration and the risk of MS.

World War II or Korean Conflict veterans with MS (5,305 in number) and pre-illness-matched controls were compared for residence at birth and entry on active duty (EAD) within three north-south tiers of states in the United States. A strong north-south gradient of MS risk was present. Migrants were defined as those whose birth and EAD tier differed. For white men of World War II, all white men, and all whites, there were highly significant reductions in risk for moves southward from either the north or middle tier, and increases in risk for moves northward from the middle tier. Increases similar in magnitude of middle to north did not attain statistical significance in the few southern-born migrants. For the small groups of black men and white men of Korean service, trends were similar but did not attain significance, whereas for white women, they were of borderline significance. Findings imply an environmental cause for MS, with acquisition years before symptom-onset.

Adult↗

PubMed2002

An ounce of prevention or a pound of cure: bioeconomic risk analysis of invasive species.

Numbers of non-indigenous species--species introduced from elsewhere - are increasing rapidly worldwide, causing both environmental and economic damage. Rigorous quantitative risk-analysis frameworks, however, for invasive species are lacking. We need to evaluate the risks posed by invasive species and quantify the relative merits of different management strategies (e.g. allocation of resources between prevention and control). We present a quantitative bioeconomic modelling framework to analyse risks from non-indigenous species to economic activity and the environment. The model identifies the optimal allocation of resources to prevention versus control, acceptable invasion risks and consequences of invasion to optimal investments (e.g. labour and capital). We apply the model to zebra mussels (Dreissena polymorpha), and show that society could benefit by spending up to US$324 000 year(-1) to prevent invasions into a single lake with a power plant. By contrast, the US Fish and Wildlife Service spent US$825 000 in 2001 to manage all aquatic invaders in all US lakes. Thus, greater investment in prevention is warranted.

Animals↗

PubMed1992

Time trends of smoking cessation: a micro-population computer simulation model.

The Micro-population model of Risk-group Dynamics (MRD) approaches smoking behavior at the level of the individual and integrates physiological and social factors to describe the evolution of behavior change in the population. MRD is innovative in several ways: (1) the model describes mathematically the interactions among these behavioral factors; (2) the model accounts for both the variability of these factors among different persons and the universality of basic rules describing these factors in all individuals; and (3) the model can be applied to various types of populations and a wide range of intervention strategies. MRD combines the physiological, psychological and social determinants into a hazard function for relapse to smoking. This hazard function is then organized into a three term expression incorporating: a baseline hazard characteristic to each individual, a decreasing term for the diminishing aspect of the initial hazard and an effect of external interventions. The model gives promising results when applied to the Multiple Risk Factors Intervention Trial (MRFIT) data using the assumptions of a Weibull distribution for the baseline hazard, a negative exponential for the decrease in the initial hazard and a constant intensity for the external intervention.

Algorithms↗

PubMed2002

What to do at low doses: a bounding approach for economic analysis.

To quantify the health benefits of environmental policies, economists generally require estimates of the reduced probability of illness or death. For policies that reduce exposure to carcinogenic substances, these estimates traditionally have been obtained through the linear extrapolation of experimental dose-response data to low-exposure scenarios as described in the U.S. Environmental Protection Agency's Guidelines for Carcinogen Risk Assessment (1986). In response to evolving scientific knowledge, EPA proposed revisions to the guidelines in 1996. Under the proposed revisions, dose-response relationships would not be estimated for carcinogens thought to exhibit nonlinear modes of action. Such a change in cancer-risk assessment methods and outputs will likely have serious consequences for how benefit-cost analyses of policies aimed at reducing cancer risks are conducted. Any tendency for reduced quantification of effects in environmental risk assessments, such as those contemplated in the revisions to EPA's cancer-risk assessment guidelines, impedes the ability of economic analysts to respond to increasing calls for benefit-cost analysis. This article examines the implications for benefit-cost analysis of carcinogenic exposures of the proposed changes to the 1986 Guidelines and proposes an approach for bounding dose-response relationships when no biologically based models are available. In spite of the more limited quantitative information provided in a carcinogen risk assessment under the proposed revisions to the guidelines, we argue that reasonable bounds on dose-response relationships can be estimated for low-level exposures to nonlinear carcinogens. This approach yields estimates of reduced illness for use in a benefit-cost analysis while incorporating evidence of nonlinearities in the dose-response relationship. As an illustration, the bounding approach is applied to the case of chloroform exposure.

Carcinogens↗

PubMed2002

Sister cities and easy passage: HIV, mobility and economies of desire in a Thai/Lao border zone.

It is recognised that people movement can increase potential risk of HIV transmission. In recent years, mobile populations moving across national borders have become a focus for HIV/AIDS prevention campaigns. These programs generally target border "hot zones" that produce high levels of HIV vulnerability due to the degree of mobility and the risk behaviours fostered by these marginal environments. However, high degrees of movement and social exploitation need not be the only criteria for borders to exacerbate HIV vulnerability. The types of social interactions promoted by mobility take many forms. In this paper we consider a border zone between Thailand and Laos to show that the links between movement and HIV vulnerability are not confined to stereotypical instances of coercion and exploitation. Rather we demonstrate that HIV risk in this area is a product of both a sense of community and a sense of difference that together foster a range of interactions based on mobility back and forth across the border. As HIV/AIDS prevention programs increasingly control forms of sexual interaction, the border provides a practical and symbolic opportunity to establish new forms of sexual relationship falling outside these constraints. This tendency to move outside bounds is not limited to border areas but has implications for prevention programs everywhere.

Cities↗

PubMed2003

Acarological risk of exposure to agents of tick-borne zoonoses in the first recognized Italian focus of Lyme borreliosis.

Acarological risk was calculated as the probability of encountering at least one host-seeking Ixodes ricinus tick infected by the pathogen Borrelia burgdorferi sensu lato, in 100 m transects in the province of Genoa, Italy. The seasonal pattern of I. ricinus was studied using generalized estimating equations (GEE) with negative binomial error, to consider overdispersion of tick counts and repeated sampling of the same dragging sites from April 1998 to March 1999. Prevalence of infection by B. burgdorferi s.l. was evaluated by PCR and hybridization with genospecies-specific probes. Acarological risk (R) peaked in April (R = 0.2, 95% CI 0.13-0.26) and November (R = 0.29, 95% CI 0.10-0.46). Borrelia garinii and B. valaisiana were the most common genospecies at our study site suggesting a major role of birds as reservoirs. DNA from Anaplasma phagocytophilum, the agent of granulocytic ehrlichiosis in humans and animals, was amplified from an adult I. ricinus.

Anaplasma↗

PubMed2000

Neural network modeling of risk assessment in child protective services.

The advantages of using neural network methodology for the modeling of complex social science data are demonstrated, and neural network analysis is applied to Washington State Child Protective Services risk assessment data. Neural network modeling of the association between social worker overall assessment of risk and the 37 separate risk factors from the State of Washington Risk Assessment Matrix is shown to provide case classification results superior to linear or logistic multiple regression. The improvement in case prediction and classification accuracy is attributed to the superiority of neural networks for modeling nonlinear relationships between interacting variables; in this respect the mathematical framework of neural networks is a better approximation to the actual process of human decision making than linear, main effects regression. The implications of this modeling advantage for evaluating social science data within the framework of ecological theories are discussed.

Child↗

PubMed1986

Impact of demographic trends on cardiovascular therapy during the next decade.

The main demographic transition during the next decade will be a worldwide increase in older and elderly people, both in proportional and absolute terms. Although age itself is the main risk factor for morbidity and disability, additional cardiovascular risk may be brought about by inherent rises of blood pressure in these older age groups. This additional risk factor appears to be a suitable target for corrective measures. Recent therapeutic trials in mild or moderate hypertension all shared the common use of thiazides as one of the basic drugs of treatment. Subgroups of older hypertensives who were randomised to active treatment tended to fare better than those on placebo. This was mainly due to a reduction in cerebrovascular complications, but in the one trial where a potassium-sparing component was added to the thiazide, cardiac events were also reduced.

Age Factors↗

PubMedDate not supplied

Status and trends of Ontario's Sydenham River ecosystem in relation to aquatic species at risk.

The Sydenham River in southwestern Ontario is located in the Mixedwood Plains Ecozone, which supports the greatest diversity of flora and fauna in Canada. The river historically supported a rich aquatic community that included 80 fishes and 34 species of freshwater mussels. Fourteen aquatic species native to the river (8 fishes, 5 mussels and 1 turtle) have been designated as endangered, threatened, or of special concern by the Committee on the Status of Species at Risk in Canada (COSEWIC). A multi-agency Recovery Team was formed in 1999 to ensure the continued survival of these and other rare species in the river. The Sydenham River Recovery Team is the first in Canada to adopt an ecosystem approach to recovery planning for aquatic species. Information on land use patterns, water quality trends, the physical condition of the river, and the distributions of aquatic species at risk was synthesized to gain an understanding of the overall health of the river and its major anthropogenic stresses. Seven of the species at risk have declined in distribution or abundance, and three may be extirpated. The main threat to fishes and mussels is heavy loadings of sediment, nutrients, and possibly pesticides to the river via tile drainage and overland runoff from agricultural lands. A strategy that incorporates four overall approaches (management, stewardship, research and monitoring, and awareness and outreach) was developed to recover and protect this globally significant freshwater ecosystem.

Animals↗

PubMed1989

The threshold of survival for systems in a fluctuating environment.

Thresholds for survival and extinction are important for assessing the risk of mortality in systems exposed to exogenous stress. For generic, rudimentary population models and the classical resource-consumer models of Leslie and Gallopin, we demonstrate the existence of a survival threshold for situations where demographic parameters are fluctuating, generally, in a nonperiodic manner. The fluctuations are assumed to be generated by exogenous, anthropogenic stresses such as toxic chemical exposures. In general, the survival threshold is determined by a relationship between mean stress measure in organisms to the ratio of the population intrinsic growth rate and stress response rate.

Animals↗

PubMed1987

Oral contraceptives. Who, which, when, and why?

The risks of oral contraceptives are very small, and they cluster in a subset of users, although warning signs of cardiovascular complications must be heeded. The best choice of an oral contraceptive is one with an estrogen content of 30 to 35 micrograms. A greater (50 micrograms) content may be necessary if breakthrough bleeding or amenorrhea persists beyond a few treatment cycles. The starting date for the pill can be up to the sixth day of the cycle. Noncontraceptive benefits of the pill may include a protective effect against endometrial and ovarian malignancy, benign breast disease, and infection of the upper genital tract. Both the contraceptive and noncontraceptive benefits of low-dose combination oral contraceptives are desirable. They far outweigh the risks in women who require a high-efficacy, reversible contraceptive and who have no significant contraindication to use of the pill.

Contraceptives, Oral↗

PubMed1999

Does social mobility affect the size of the socioeconomic mortality differential?: evidence from the Office for National Statistics Longitudinal Study.

"The effect of social mobility on the socioeconomic differential in mortality is examined with data from the Office for National Statistics Longitudinal Study. The analyses involve 46,980 men aged 45-64 years in 1981. The mortality risk of the socially mobile is compared with the mortality risk of the socially stable after adjustment for their class of origin (their social class in 1971) and class of destination (their social class in 1981) separately. Among those in employment there is some evidence that movement out of their class of origin is in the direction predicted by the idea of health-related social mobility. This evidence, however, seems strongest for causes of death which are least likely to have been preceded by prolonged incapacity. Movement into the class of destination, however, shows the opposite relationship with mortality."

Age Factors↗

PubMed2006

Harvest reserves reduce extinction risk in an experimental microcosm.

Overharvesting by humans threatens a substantial fraction of endangered species. Reserves have recently received enormous attention as a means of better conserving harvested resources, despite limited empirical evidence of their efficacy. We used manipulated microcosms to test whether reserves reduce extinction risk in mobile populations of harvested Tetrahymena thermophila, a ciliate. Here we show that patterns of population distribution inside and outside reserves can be accurately predicted on the basis of simple models of diffusion coupled with logistic controls on local population growth. No extinctions occurred in eight experimental trials with reserves, whereas extinction occurred in seven of eight trials without reserves, as predicted by population viability models based on stochastic population processes. These results suggest that marine reserves may be an effective means of improving long-term viability in heavily harvested fish species.

Animals↗