World Health Organization

About: World Health Organization is a government organization based out in Islamabad, Pakistan. It is known for research contribution in the topics: Population & Public health. The organization has 13330 authors who have published 22232 publications receiving 1322023 citations. The organization is also known as: World Health Organisation & WHO.

The weight of nations: an estimation of adult human biomass

Abstract: The energy requirement of species at each trophic level in an ecological pyramid is a function of the number of organisms and their average mass. Regarding human populations, although considerable attention is given to estimating the number of people, much less is given to estimating average mass, despite evidence that average body mass is increasing. We estimate global human biomass, its distribution by region and the proportion of biomass due to overweight and obesity. For each country we used data on body mass index (BMI) and height distribution to estimate average adult body mass. We calculated total biomass as the product of population size and average body mass. We estimated the percentage of the population that is overweight (BMI > 25) and obese (BMI > 30) and the biomass due to overweight and obesity. In 2005, global adult human biomass was approximately 287 million tonnes, of which 15 million tonnes were due to overweight (BMI > 25), a mass equivalent to that of 242 million people of average body mass (5% of global human biomass). Biomass due to obesity was 3.5 million tonnes, the mass equivalent of 56 million people of average body mass (1.2% of human biomass). North America has 6% of the world population but 34% of biomass due to obesity. Asia has 61% of the world population but 13% of biomass due to obesity. One tonne of human biomass corresponds to approximately 12 adults in North America and 17 adults in Asia. If all countries had the BMI distribution of the USA, the increase in human biomass of 58 million tonnes would be equivalent in mass to an extra 935 million people of average body mass, and have energy requirements equivalent to that of 473 million adults. Increasing population fatness could have the same implications for world food energy demands as an extra half a billion people living on the earth.

Peak bone mass.

Abstract: Peak bone mass, which can be defined as the amount of bony tissue present at the end of the skeletal maturation, is an important determinant of osteoporotic fracture risk.Measurement of bone mass development. The bone mass of a given part of the skeleton is directly dependent upon both its volume or size and the density of the mineralized tissue contained within the periosteal envelope. The techniques of single-1 and dual-energy photon or X-ray absorptiometry measure the so-called ‘areal’ or ‘surface’ bone mineral density (BMD), a variable which has been shown to be directly related to bone strength.Bone mass gain during puberty. During puberty the gender difference in bone mass becomes expressed. This difference appears to be essentially due to a more prolonged bone maturation period in males than in females, with a larger increase in bone size and cortical thickness. Puberty affects bone size much more than the volumetric mineral density. There is no significant sex difference in the volumetric trabecular density at the end of pubertal maturation. During puberty, the accumulation rate in areal BMD at both the lumbar spine and femoral neck levels increases to four- to sixfold over a 3-and 4-year period in females and males, respectively. Change in bone mass accumulation rate is less marked in long bone diaphyses. There is an asynchrony between the gain in statural height and bone mass growth. This phenomenon may be responsible for the occurrence of a transient period of a relative increase in bone fragility that may account for the pattern of fracture incidence during adolescence.Variance in peak bone mass. At the beginning of the third decade there is a large variability in the normal values of areal BMD in the axial and appendicular skeleton. This large variance, which is observed at sites particularly susceptible to osteoporotic fractures such as lumbar spine and femoral neck, is barely reduced after correction for statural height, and does not appear to increase substantially during adult life. The height-independent broad variance in bone mass develops during puberty at sites such as lumbar spine and femoral neck, where the accretion rate is markedly increased.Time of peak bone mass attainment. Despite the fact that a majority of studies did not indicate that bone mass continues to accumulate significantly during the third and fourth decades, it has been generally accepted that peak bone mass at any skeletal site is attained in both sexes during the mid-thirties. However, recent studies indicate that in healthy Caucasian females with apparently adequate intakes of energy and calcium, bone mass accumulation can virtually be completed before the end of the second decade, for both lumbar spine and femoral neck. It is possible that both genetic and environmental factors could influence the time of peak bone mass achievement.Determinants of peaks bone mass. Several variables, more or less independent, are supposed to influence bone mass accumulation during growth; heredity, sex, dietary components, endocrine factors, mechanical forces, and exposure to risk factors. Quantitatively, the most prominent factor appears to be the genetic determinant, as estimated by studies comparing monozygotic and dizygotic twins. That heredity is not to be the only determinant of peak bone mass is of practical interest, since environmental factors can be modified. With respect to nutrition, the quantitative importance of calcium intake in bone mass accumulation during growth, particularly at sites prone to osteoporotic fractures, remains to be clearly determined. The same can be said for the impact of physical activity. Finally, the crucial years when these external factors will be particularly effective on bone mass accumulation remain to be determined by longitudinal prospective studies in order to produce credible and well targeted recommendations for the setting up of osteoporosis prevention programs aimed at maximizing peak bone mass.

Exposure assessment for estimation of the global burden of disease attributable to outdoor air pollution.

Abstract: Ambient air pollution is associated with numerous adverse health impacts. Previous assessments of global attributable disease burden have been limited to urban areas or by coarse spatial resolution of concentration estimates. Recent developments in remote sensing, global chemical-transport models, and improvements in coverage of surface measurements facilitate virtually complete spatially resolved global air pollutant concentration estimates. We combined these data to generate global estimates of long-term average ambient concentrations of fine particles (PM2.5) and ozone at 0.1° × 0.1° spatial resolution for 1990 and 2005. In 2005, 89% of the world’s population lived in areas where the World Health Organization Air Quality Guideline of 10 μg/m3 PM2.5 (annual average) was exceeded. Globally, 32% of the population lived in areas exceeding the WHO Level 1 Interim Target of 35 μg/m3, driven by high proportions in East (76%) and South (26%) Asia. The highest seasonal ozone levels were found in North and Latin...