Global burden and strength of evidence for 88 risk factors in 204 countries and 811 subnational locations, 1990–2021: a systematic analysis for the Global Burden of Disease Study 2021

Background: Understanding the health consequences associated with exposure to risk factors is necessary to inform public health policy and practice. To systematically quantify the contributions of risk factor exposures to specific health outcomes, the Global Burden of Diseases, Injuries, and Risk Factors Study (GBD) 2021 aims to provide comprehensive estimates of exposure levels, relative health risks, and attributable burden of disease for 88 risk factors in 204 countries and territories and 811 subnational locations, from 1990 to 2021. Methods: The GBD 2021 risk factor analysis used data from 54 561 total distinct sources to produce epidemiological estimates for 88 risk factors and their associated health outcomes for a total of 631 risk–outcome pairs. Pairs were included on the basis of data-driven determination of a risk–outcome association. Age-sex-location-year-specific estimates were generated at global, regional, and national levels. Our approach followed the comparative risk assessment framework predicated on a causal web of hierarchically organised, potentially combinative, modifiable risks. Relative risks (RRs) of a given outcome occurring as a function of risk factor exposure were estimated separately for each risk–outcome pair, and summary exposure values (SEVs), representing risk-weighted exposure prevalence, and theoretical minimum risk exposure levels (TMRELs) were estimated for each risk factor. These estimates were used to calculate the population attributable fraction (PAF; ie, the proportional change in health risk that would occur if exposure to a risk factor were reduced to the TMREL). The product of PAFs and disease burden associated with a given outcome, measured in disability-adjusted life-years (DALYs), yielded measures of attributable burden (ie, the proportion of total disease burden attributable to a particular risk factor or combination of risk factors). Adjustments for mediation were applied to account for relationships involving risk factors that act indirectly on outcomes via intermediate risks. Attributable burden estimates were stratified by Socio-demographic Index (SDI) quintile and presented as counts, age-standardised rates, and rankings. To complement estimates of RR and attributable burden, newly developed burden of proof risk function (BPRF) methods were applied to yield supplementary, conservative interpretations of risk–outcome associations based on the consistency of underlying evidence, accounting for unexplained heterogeneity between input data from different studies. Estimates reported represent the mean value across 500 draws from the estimate's distribution, with 95% uncertainty intervals (UIs) calculated as the 2·5th and 97·5th percentile values across the draws. Findings: Among the specific risk factors analysed for this study, particulate matter air pollution was the leading contributor to the global disease burden in 2021, contributing 8·0% (95% UI 6·7–9·4) of total DALYs, followed by high systolic blood pressure (SBP; 7·8% [6·4–9·2]), smoking (5·7% [4·7–6·8]), low birthweight and short gestation (5·6% [4·8–6·3]), and high fasting plasma glucose (FPG; 5·4% [4·8–6·0]). For younger demographics (ie, those aged 0–4 years and 5–14 years), risks such as low birthweight and short gestation and unsafe water, sanitation, and handwashing (WaSH) were among the leading risk factors, while for older age groups, metabolic risks such as high SBP, high body-mass index (BMI), high FPG, and high LDL cholesterol had a greater impact. From 2000 to 2021, there was an observable shift in global health challenges, marked by a decline in the number of all-age DALYs broadly attributable to behavioural risks (decrease of 20·7% [13·9–27·7]) and environmental and occupational risks (decrease of 22·0% [15·5–28·8]), coupled with a 49·4% (42·3–56·9) increase in DALYs attributable to metabolic risks, all reflecting ageing populations and changing lifestyles on a global scale. Age-standardised global DALY rates attributable to high BMI and high FPG rose considerably (15·7% [9·9–21·7] for high BMI and 7·9% [3·3–12·9] for high FPG) over this period, with exposure to these risks increasing annually at rates of 1·8% (1·6–1·9) for high BMI and 1·3% (1·1–1·5) for high FPG. By contrast, the global risk-attributable burden and exposure to many other risk factors declined, notably for risks such as child growth failure and unsafe water source, with age-standardised attributable DALYs decreasing by 71·5% (64·4–78·8) for child growth failure and 66·3% (60·2–72·0) for unsafe water source. We separated risk factors into three groups according to trajectory over time: those with a decreasing attributable burden, due largely to declining risk exposure (eg, diet high in trans-fat and household air pollution) but also to proportionally smaller child and youth populations (eg, child and maternal malnutrition); those for which the burden increased moderately in spite of declining risk exposure, due largely to population ageing (eg, smoking); and those for which the burden increased considerably due to both increasing risk exposure and population ageing (eg, ambient particulate matter air pollution, high BMI, high FPG, and high SBP). Interpretation: Substantial progress has been made in reducing the global disease burden attributable to a range of risk factors, particularly those related to maternal and child health, WaSH, and household air pollution. Maintaining efforts to minimise the impact of these risk factors, especially in low SDI locations, is necessary to sustain progress. Successes in moderating the smoking-related burden by reducing risk exposure highlight the need to advance policies that reduce exposure to other leading risk factors such as ambient particulate matter air pollution and high SBP. Troubling increases in high FPG, high BMI, and other risk factors related to obesity and metabolic syndrome indicate an urgent need to identify and implement interventions. Funding: Bill & Melinda Gates Foundation

Recents developments in cowpea germplasm collection, conservation, evaluation and research at the Genetic Resources Unit

The history of the Genetic Resources Unit at the International Institute of Tropical Agriculture (IITA) was highlighted. By 1980, the unit engaged in characterization and evaluation of germplasm information. In order to strengthen the units activity and provide a better knowledge of Vigna, the government of Italy funded a project from December 1984 to December 1989. Information on the geographical distribution of Vigna were also given. The unit now maintains 923 accessions of wild vigna species and about 15,200 accessions of cultivated cowpea

Preservation of genetic resources by seed storage

Several ways exist of maintaining the genetic resources of crops. The cheapest and most convenient way is by storing seeds. However, not all crops can be preserved by storing their seeds, because they are either vegetatively propagated and/or do not produce seeds, or the period of their seed viability is short. Maximizing the longevity of seeds requires a good seed store and knowledge of the principles of seed preservation. This document discusses types of seed, techniques for preparing seeds for storage, factors controlling longevity of seed, standards of seed stores for genetic resources conservation, and design of seed stores

Wide crosses of Vigna food legumes

Many successful wide crosses among Asiatic cultivated Vigna species and between them and a wild species, V. trilobata, have been reported However, despite many attempts to cross the African cultivated Vigna species with wild Vigna species and the Asiatic cultivated Vigna species, there has been no success as yet. Nevertheless, crosses between cultivated and wild subspecies of V. unguiculata were fairly easy and their hybrids are fertile. Studies conducted at the International Institute of Tropical Agriculture (IITA) have shown that crossing barriers between V. unguiculata and several African wild Vigna species were due to abortion ofyoung embryos and pollen-pistil incompatibility. With more basic research on reproductive biology and tissue culture, and a larger number of crosses among species and genotypes, there will be a greater chance of success for wide crosses between V. unguiculata and wild Vigna species which possess some very desirable traits for the improvement of this cultivated specie

Conservation des ressources genetiques par le stockage des graines

Il existe pi usieurs facons de conserver les ressources genetiques des cultures. La methode la moins chere et la plus simple consiste a stocker les graines. Toutefois, ce n'est pas toutes les cultures qui peuvent etre conservees sous forme de graines, car certaines se propagent vegetativement et produisent ou ne pro• duisent pas de graines; quand elles en,produisent, la viabilite de celles-ci est courte. Pour prolonger au maxi-mum la duree de vie des graines, il faut un bon entrepot et la maitrise des principes de la conservation des graines. Ce Guide traite des types de graines, des techniques de preparation des graines pour I'entreposage, des facteurs afferents a la duree de vie des graines, des normes des entrepots de graines pour la conservation des ressources genetiques et de la conception des entre pats de grains

Embryological study of crosses between Vigna unguiculata and V. vexillata

Early embryogenesis up to 8 days after pollination was characterized in V. unguiculata. When crosses were performed between V. unguiculata and wild V. vexillata, seeds were not obtained due to crossability barriers. In most cases pollen tube growth was arrested in the stigmatic tissue. In the 15-20% of ovules which were fertilized, embryo development was normal up to the globular stage, but then (5-8 days after pollination) the embryo began to collapse