Environment Counts | Estimating the environmental burden of disease
Author: Rick Higgins – Published At: 2012-04-17 11:34 – (1864 Reads)
Globally an estimated 24% of the disease burden (healthy life years lost) and an estimated 23% of all deaths (premature mortality) is attributable to environmental factors, and among children 0â€“14 years, the proportion of deaths attributed to the environment was as high as 36%. Large regional differences in the environmental contribution to various disease conditions occur particularly between developed and developing regions and countries. On average, children in developing countries lost 8-times more healthy life years than their counterparts in developed countries, but for some key diseases the differences were astounding. These are among many findings in a World Health Organization report estimating the environental burden of disease. Although this represents a significant contribution to the overall global disease burden, the report states it is a conservative estimate because there is as yet no evidence available globally for many diseases. The World Health Organization – WHO – is a UN agency. WHO, 2006
The report details the health impacts of environmental risks across more than 80 diseases and injuries on which it was able to obtain global data and analysis. The report states this analysis represents the result of a systematic process for estimating environmental burden of disease that is unprecedented in terms of rigor, transparency and comprehensiveness. The report also states that it incorporates the best available scientific evidence on population risk from environmental hazards currently available.
How significant is the impact of environment on health?
An estimated 24% of the global disease burden and 23% of all deaths can be attributed to environmental factors.
Globally, an estimated 24% of the disease burden (healthy life years lost) and an estimated 23% of
all deaths (premature mortality) was attributable to environmental factors. Among children 0â€“14
years of age, the proportion of deaths attributed to the environment was as high as 36%. There
were large regional differences in the environmental contribution to various disease conditions â€“
due to differences in environmental exposures and access to health care across the regions. For
example, although 25% of all deaths in developing regions were attributable to environmental
causes, only 17% of deaths were attributed to such causes in developed regions. Although this
represents a significant contribution to the overall disease burden, it is a conservative estimate
because there is as yet no evidence for many diseases.
By focusing on the disease endpoint, and how various kinds of diseases are impacted by environmental influences, the analysis forges new ground in an understanding of interactions between environment and health. The estimates, in effect, reflect how much death, illness and disability could realistically be
avoided every year as a result of reduced human exposures to environmental hazards.
Examples of factors included in, or excluded from, the report definition for “environment”
Included environmental factors are the modifiable parts (or impacts) of:
â€¢ pollution of air, water, or soil with chemical or biological agents;
â€¢ UV and ionizing radiationa;
â€¢ noise, electromagnetic fields;
â€¢ occupational risks;
â€¢ built environments, including housing, land use patterns, roads;
â€¢ agricultural methods, irrigation schemes;
â€¢ man-made climate change, ecosystem change;
â€¢ behaviour related to the availability of safe water and sanitation facilities, such as washing hands, and contaminating food with unsafe water or unclean hands.
Excluded environmental factors are:
â€¢ alcohol and tobacco consumption, drug abuse;
â€¢ diet (although it could be argued that food availability influences diet);
â€¢ the natural environments of vectors that cannot reasonably be modified (e.g. in rivers, lakes, wetlands);
â€¢ impregnated bed nets (for this study they are considered to be nonenvironmental interventions);
â€¢ unemployment (provided that it is not related to environmental degradation, occupational disease, etc.);
â€¢ natural biological agents, such as pollen in the outdoor environment;
â€¢ person-to-person transmission that cannot reasonably be prevented through environmental interventions such as improving housing, introducing sanitary hygiene, or making improvements in the occupational environment.
Disease burden on children in developing countries
On average, children in developing countries lost 8-times more healthy life years than their counterparts in developed countries from environmentally-related diseases. For some key diseases, the gap is far greater.
Globally, the per capita number of healthy life years lost to environmental risk factors was about 5-fold greater in children under five years of age than in the total population. The difference was even greater (7â€”10 -fold greater) for major diseases, such as upper and lower respiratory infections, diarrhoea, malaria and malnutrition. The differences would have been larger if the noncommunicable diseases rates for children had not been very low.
On average, children in developing countries lost 8-times more healthy life years than their counterparts in developed countries, but for key diseases the differences were astounding. For childhood cluster diseases, the per capita rates in developing countries were over 70-times higher than in developed countries. At subregional level, the differential was greater than 25 for road traffic injuries, 140 for diarrhoeal diseases, and 800 for lower respiratory infections.
Definition and survey
The definition of the â€œenvironmentâ€ used by the WHO in the study is: â€œThe environment is all the physical, chemical and biological factors external to the human host, and all related behaviours, but excluding those natural environments that cannot reasonably be modified. This definition excludes behaviour not related to environment, as well as behaviour related to the social and cultural environment, genetics, and parts of the natural environment.â€
The report involved not only a systematic literature review in all of the disease categories addressed, but also a survey of more than 100 experts worldwide. As such, this analysis represents the result of a systematic process for estimating environmental burden of disease that is unprecedented in terms of rigor, transparency and comprehensiveness. It incorporates the best available scientific evidence on population risk from environmental hazards currently available. While not an official WHO estimate of environmental burden of disease, as such, it is an important input.