Evaluation of take-home exposure to asbestos from handling asbestos-contaminated worker clothing following the abrasive sawing of cement pipe.

Although industrial uses of asbestos have declined since the 1970s, in recent years there has been a renewed interest in para-occupational ("take-home") exposure to these fibers. The aim of this study was to quantify the release of asbestos fibers, if any, during the shaking out of crocidolite- and chrysotile-contaminated clothing in a simulated at-home setting. An exposure study was conducted in which personal and area air samples were collected during the handling (i.e. shake-out) of work clothing (shirt and pants) previously worn by an operator who had cut asbestos-containing cement pipe. During eight "loading" events, the operator cut a historically representative asbestos-containing cement pipe (10% crocidolite and 25% chrysotile) using a powered abrasive saw. Subsequently, 30-minute air samples were collected during four "shake-out" events, each of which consisted of the handling of two complete sets of contaminated work clothes. Samples were analyzed in accordance with NIOSH methods 7400 and 7402. The mean phase contrast microscopy equivalent (PCME) airborne concentrations were 0.52 f/cc (SD = 0.34 f/cc) for total asbestos fibers, 0.36 f/cc (SD = 0.26 f/cc) for chrysotile and 0.17 f/cc (SD = 0.096 f/cc) for crocidolite. Based on likely estimates of the frequency of laundering activities, and assuming that the dusty clothing (1) is not blown off in the occupational setting using compressed air and (2) is not shaken out before entering the home, a family member handling the clothing could potentially have a lifetime cumulative exposure to chrysotile and crocidolite of approximately 0.20 f/cc-year and 0.096 f/cc-year, respectively.

Are well functioning civil registration and vital statistics systems associated with better health outcomes?

In this Series paper, we examine whether well functioning civil registration and vital statistics (CRVS) systems are associated with improved population health outcomes. We present a conceptual model connecting CRVS to wellbeing, and describe an ecological association between CRVS and health outcomes. The conceptual model posits that the legal identity that civil registration provides to individuals is key to access entitlements and services. Vital statistics produced by CRVS systems provide essential information for public health policy and prevention. These outcomes benefit individuals and societies, including improved health. We use marginal linear models and lag-lead analysis to measure ecological associations between a composite metric of CRVS performance and three health outcomes. Results are consistent with the conceptual model: improved CRVS performance coincides with improved health outcomes worldwide in a temporally consistent manner. Investment to strengthen CRVS systems is not only an important goal for individuals and societies, but also a development imperative that is good for health.

A flexible two-dimensional mortality model for use in indirect estimation.

Mortality estimates for many populations are derived using model life tables, which describe typical age patterns of human mortality. We propose a new system of model life tables as a means of improving the quality and transparency of such estimates. A flexible two-dimensional model was fitted to a collection of life tables from the Human Mortality Database. The model can be used to estimate full life tables given one or two pieces of information: child mortality only, or child and adult mortality. Using life tables from a variety of sources, we have compared the performance of new and old methods. The new model outperforms the Coale-Demeny and UN model life tables. Estimation errors are similar to those produced by the modified Brass logit procedure. The proposed model is better suited to the practical needs of mortality estimation, since both input parameters are continuous yet the second one is optional.

The lifetime risk of maternal mortality: concept and measurement.

OBJECTIVE: The lifetime risk of maternal mortality, which describes the cumulative loss of life due to maternal deaths over the female life course, is an important summary measure of population health. However, despite its interpretive appeal, the lifetime risk of dying from maternal causes can be defined and calculated in various ways. A clear and concise discussion of both its underlying concept and methods of measurement is badly needed. METHODS: I define and compare a variety of procedures for calculating the lifetime risk of maternal mortality. I use detailed survey data from Bangladesh in 2001 to illustrate these calculations and compare the properties of the various risk measures. Using official UN estimates of maternal mortality for 2005, I document the differences in lifetime risk derived with the various measures. FINDINGS: Taking sub-Saharan Africa as an example, the range of estimates for the 2005 lifetime risk extends from 3.41% to 5.76%, or from 1 in 29 to 1 in 17. The highest value resulted from the method used for producing official UN estimates for the year 2000. The measure recommended here has an intermediate value of 4.47%, or 1 in 22. CONCLUSION: There are strong reasons to consider the calculation method proposed here more accurate and appropriate than earlier procedures. Accordingly, it was adopted for use in producing the 2005 UN estimates of the lifetime risk of maternal mortality. By comparison, the method used for the 2000 UN estimates appears to overestimate this important measure of population health by around 20%.

The United Nations Probabilistic Population Projections: An Introduction to Demographic Forecasting with Uncertainty.

The United Nations publishes projections of populations around the world and breaks these down by age and sex. Traditionally, they are produced with standard demographic methods based on assumptions about future fertility rates, survival probabilities, and migration counts. Such projections, however, were not accompanied by formal statements of uncertainty expressed in probabilistic terms. In July 2014 the UN for the first time issued official probabilistic population projections for all countries to 2100. These projections quantify uncertainty associated with future fertility and mortality trends worldwide. This review article summarizes the probabilistic population projection methods and presents forecasts for population growth over the rest of this century.

World population stabilization unlikely this century.

The United Nations (UN) recently released population projections based on data until 2012 and a Bayesian probabilistic methodology. Analysis of these data reveals that, contrary to previous literature, the world population is unlikely to stop growing this century. There is an 80% probability that world population, now 7.2 billion people, will increase to between 9.6 billion and 12.3 billion in 2100. This uncertainty is much smaller than the range from the traditional UN high and low variants. Much of the increase is expected to happen in Africa, in part due to higher fertility rates and a recent slowdown in the pace of fertility decline. Also, the ratio of working-age people to older people is likely to decline substantially in all countries, even those that currently have young populations.

Understanding global trends in maternal mortality.

CONTEXT: Despite the fact that most maternal deaths are preventable, maternal mortality remains high in many developing countries. Target A of Millennium Development Goal (MDG) 5 calls for a three-quarters reduction in the maternal mortality ratio (MMR) between 1990 and 2015. METHODS: We derived estimates of maternal mortality for 172 countries over the period 1990-2008. Trends in maternal mortality were estimated either directly from vital registration data or from a hierarchical or multilevel model, depending on the data available for a particular country. RESULTS: The annual number of maternal deaths worldwide declined by 34% between 1990 and 2008, from approximately 546,000 to 358,000 deaths. The estimated MMR for the world as a whole also declined by 34% over this period, falling from 400 to 260 maternal deaths per 100,000 live births. Between 1990 and 2008, the majority of the global burden of maternal deaths shifted from Asia to Sub-Saharan Africa. Differential trends in fertility, the HIV/AIDS epidemic and access to reproductive health are associated with the shift in the burden of maternal deaths from Asia to Sub-Saharan Africa. CONCLUSIONS: Although the estimated annual rate of decline in the global MMR in 1990-2008 (2.3%) fell short of the level needed to meet the MDG 5 target, it was much faster than had been thought previously. Targeted efforts to improve access to quality maternal health care, as well as efforts to decrease unintended pregnancies through family planning, are necessary to further reduce the global burden of maternal mortality.

A New Method for Deriving Global Estimates of Maternal Mortality.

Maternal mortality is widely regarded as a key indicator of population health and of social and economic development. Its levels and trends are monitored closely by the United Nations and others, inspired in part by the UN's Millennium Development Goals (MDGs), which call for a three-fourths reduction in the maternal mortality ratio between 1990 and 2015. Unfortunately, the empirical basis for such monitoring remains quite weak, requiring the use of statistical models to obtain estimates for most countries. In this paper we describe a new method for estimating global levels and trends in maternal mortality. For countries lacking adequate data for direct calculation of estimates, we employed a parametric model that separates maternal deaths related to HIV/AIDS from all others. For maternal deaths unrelated to HIV/AIDS, the model consists of a hierarchical linear regression with three predictors and variable intercepts for both countries and regions. The uncertainty of estimates was assessed by simulating the estimation process, accounting for variability both in the data and in other model inputs. The method was used to obtain the most recent set of UN estimates, published in September 2010. Here, we provide a concise description and explanation of the approach, including a new analysis of the components of variability reflected in the uncertainty intervals. Final estimates provide evidence of a more rapid decline in the global maternal mortality ratio than suggested by previous work, including another study published in April 2010. We compare findings from the two recent studies and discuss topics for further research to help resolve differences.

Estimating the effect of smoking on slowdowns in mortality declines in developed countries.

Declines in mortality rates for females at older ages in some developed countries, including the United States, have slowed in recent decades even as decreases have steadily continued in some other countries. This study presents a modified version of the indirect Peto-Lopez method, which uses lung cancer mortality rates as a proxy for smoking exposure, to analyze this trend. The modified method estimates smoking-attributable mortality for more-specific age groups than does the Peto-Lopez method. An adjustment factor is also introduced to account for low mortality in the indirect method's study population. These modifications are shown to be useful specifically in the estimation of deaths attributable to smoking for females at older ages, and in the estimation of smoking-attributable mortality more generally. In a comparison made between the United States and France with the modified method, smoking is found to be responsible for approximately one-half the difference in life expectancy for females at age 65.

A new method for estimating smoking-attributable mortality in high-income countries.

BACKGROUND: Cigarette smoking is responsible for a massive loss of life in both developed and developing countries. This article develops an alternative to the Peto-Lopez method for estimating the number or fraction of smoking-attributable deaths in high-income countries. METHODS: We use lung cancer death rates as an indicator of the damage caused by smoking. Using administrative data for the population aged > or =50 years from 20 high-income countries in the period from 1950 to 2006, we estimate a negative binomial regression model that predicts mortality from causes other than lung cancer as a function of lung cancer mortality and other variables. Using this regression model, we estimate smoking-attributable deaths based on the difference between observed death rates from lung cancer and expected rates among non-smokers. RESULTS: Combining the estimated number of excess deaths from lung cancer with those from other causes, we find that among males in 1955 the smoking-attributable fraction was highest in Finland (18%); among women, no country exceeded 1%. By 2003, Hungary had the highest fraction of smoking-attributable deaths among males (32%), whereas the USA held that position among women (24%). Our estimates are remarkably similar to those produced by the Peto-Lopez method, a result that supports the validity of each approach. CONCLUSIONS: We provide a simple and straightforward method for estimating the proportion of deaths attributable to smoking in high-income countries. Our results demonstrate that smoking has played a central role in levels, trends and international differences in mortality over the past half century.

A decomposition method based on a model of continuous change.

A demographic measure is often expressed as a deterministic or stochastic function of multiple variables (covariates), and a general problem (the decomposition problem) is to assess contributions of individual covariates to a difference in the demographic measure (dependent variable) between two populations. We propose a method of decomposition analysis based on an assumption that covariates change continuously along an actual or hypothetical dimension. This assumption leads to a general model that logically justifies the additivity of covariate effects and the elimination of interaction terms, even if the dependent variable itself is a nonadditive function. A comparison with earlier methods illustrates other practical advantages of the method: in addition to an absence of residuals or interaction terms, the method can easily handle a large number of covariates and does not require a logically meaningful ordering of covariates. Two empirical examples show that the method can be applied flexibly to a wide variety of decomposition problems. This study also suggests that when data are available at multiple time points over a long interval, it is more accurate to compute an aggregated decomposition based on multiple subintervals than to compute a single decomposition for the entire study period.

Life-long sustained mortality advantage of siblings of centenarians.

Although survival to old age is known to have strong environmental and behavioral components, mortality differences between social groups tend to diminish or even disappear at older ages. Hypothesizing that surviving to extreme old age entails a substantial familial predisposition for longevity, we analyzed the pedigrees of 444 centenarian families in the United States. These pedigrees included 2,092 siblings of centenarians, whose survival was compared with 1900 birth cohort survival data from the U.S. Social Security Administration. Siblings of centenarians experienced a mortality advantage throughout their lives relative to the U.S. 1900 cohort. Female siblings had death rates at all ages about one-half the national level; male siblings had a similar advantage at most ages, although diminished somewhat during adolescence and young adulthood. Relative survival probabilities for these siblings increase markedly at older ages, reflecting the cumulative effect of their mortality advantage throughout life. Compared with the U.S. 1900 cohort, male siblings of centenarians were at least 17 times as likely to attain age 100 themselves, while female siblings were at least 8 times as likely.