An undeniable link…
The close link between health and socio-economic and environmental factors has been widely acknowledged for some time.
This is illustrated by the 2016 WHO report, which estimates that nearly a quarter (23%) of premature deaths in the world in 2012 were attributable to the environment, i.e. 12.6 million people who died before the age of 65 (Prüss-Ustün et al., 2016).
Although the number of deaths caused by infectious diseases is decreasing, deaths due to noncontagious diseases are increasing, and particularly strokes, heart disease, cancer and chronic respiratory disease, which are responsible for nearly two thirds of deaths related to environmental causes. The main environmental risk factors are air, water and ground pollution, exposure to chemical substances and climatic change.
Number of premature deaths worldwide in 2012 that are linked to an environmental cause (modified from Prüss-Ustün et al., 2016).
Air pollution is a major cause of morbidity and mortality. Among the 3000 cities with more than 100,000 inhabitants where air quality is monitored, 80% of people live in an environment that does meet the criteria set out by the WHO. Air pollution varies in the different regions of the world, having the greatest impact on populations living in low-income cities. These people have higher risks of strokes, lung cancer and acute respiratory conditions. This is acknowledged by the IARC, who decided to classify diesel emissions and outdoor air pollution as certain carcinogens (group 1) in 2013.
In June 2016, a study carried out by Santé Publique France (Public Health France) revealed that 48,000 deaths per year in France are linked to air pollution by fine particles (PM2.5) resulting from human activity. The APHEKOM programme (2008-2011) covered 12 countries and 25 cities across Europe, and concluded that levels of atmospheric particles that exceeded recommended WHO values result in 19,000 premature deaths each year, 15,000 of which are due to cardiovascular causes.
Although this pollution has the strongest effects in large cities, medium and small cities as well as rural areas are also concerned:
- In urban areas with more than 100,000 inhabitants, the results show an average loss of 15 months of life expectancy at the age of 30 due to PM 2.5 levels;
- In areas with a population of between 2,000 and 100,000 inhabitants, the average loss of life expectancy is 10 months;
- In rural areas, an average loss of 9 months of life expectancy is estimated.
For example, almost 6 months of life expectancy could be gained in Lille if the guide values for fine particles were respected (10µg / m3).
Pathways and Health Effects of Suspended Particulate Matter (Modified from APPA and Pascal & Medina, 2012).
The effect of air pollution on health costs Europe 31.5 billion euros, 5 billion euros of which concern France. These costs correspond to health expenses and associated costs.
The geographic dimension plays a central role in population exposure to environmental risk factors. Proximity to sources of pollution increases the risk of illness. Approximately 15-30% of new childhood asthma cases could attributable to living close to roads with high levels of traffic, which is also true for similar or higher proportions of chronic respiratory and cardiovascular disease that are common in adults aged 65 and over (Pascal and Medina, 2012).
… but difficult to characterize.
However, it remains difficult to characterize and quantify this health-environment link. This is notably due to the multitude of contexts in which humans can be exposed (environment, lifestyle, profession) and the non-specificity of health responses (i.e. a number of possible pathologies for the same context, or multifactorial diseases). Additionally, certain pathologies may or may not be visible depending on the exposure period (latency period) and the genetic susceptibility of individuals (individual variability). The health status of a population can therefore be affected by a complex set of individual determinants and social and environmental factors.
Principles and stakes in environmental health
According to the definition proposed by the World Health Organization in 1994 at the Helsinki conference:
« Environmental health includes aspects of human health, including the quality of life, which are determined by the physical, chemical, biological, social, psychosocial and aesthetic factors of our environment. It also concerns all policy and practices designed for the assessing, correcting, controlling, and preventing of those factors in the environment that can potentially affect adversely the health of present and future generations. »
This WHO definition considers all exogenous factors, that is to say those that are not intrinsic to the person (such as genetic factors) including factors that are related to individual choices, practices or lifestyles such as smoking, physical activity, etc. Environmental health (also called the health-environment approach) therefore covers many areas and can have very different meanings depending on which of these two perspectives (public health or environment) is chosen at the outset of analysis. The multiplicity of concepts that experts must consider increases the complexity of this approach.
The objective of environmental health research programs is is to formulate hypotheses and produce and disseminate knowledge about the possible relationships between two dimensions, namely:
- the quality of the environment (air, water, soil), which can be affected by the presence of pollutants such as pesticides, metallic trace elements, fine and ultrafine particles, noise and electromagnetic fields. Populations can be exposed by inhalation (gases, vapors, dust, aerosols), ingestion (food, water, soil, dust) and/or skin absorption (dust, liquids, gas); and
- the general health of populations: chronic changes in the state of health, leading to increased incidence of chronic diseases such as cancers, chronic renal failure or asthma, or acute diseases (myocardial infarction, for example).
Recent studies have provided some evidence of a correlation between exposure to a deteriorated environment and a degraded state of health, but further research is required before it can be confirmed with certainty. Humans are exposed to a range of pollutants, either simultaneously or at different stages of their development. The combined effects of hazardous substances are poorly understood to date, and the risks associated with exposure to a combination of pollutants have yet to be clearly identified. In addition to the question of multiple exposure, researchers must also into account take more complex parameters such as variable exposure time and different levels of sensitivity in individuals such as pregnant women and people under the age of 15 or over 75. There may also be a delay between the period of exposure to pollutants and the appearance of health effects in the population. This can be a few hours for cardiac arrest or several decades for cancer.
Social inequalities in environment and health (SIEH): a key issue
The issue of social inequalities in environment and health is directly linked to two compounding elements: the level of the population’s exposure to a degraded living environment and the level of vulnerability to risk factors that can affect health (Besse et al., 2014). Populations facing severe precarity are more exposed to environmental pollution and are more vulnerable to the resulting health effects (WHO, 2012). As the geographical factor is essential in the health-environment relationship, these inequalities can be considered on a territorial scale (i.e. territorial inequalities).
The study of these inequalities initially concentrated on populations living close to polluting industries or major highways (Brown, 1995; Neumann et al., 1998; Perlin et al., 1999; Gunier et al., 2003), but now seeks to characterize links between indicators of health, socio-economic factors and environmental quality. These are often modeled or measured by physico-chemical analysis, but can also be evaluated via environmental biomonitoring. The most socially vulnerable groups are more fragile and are exposed to harmful environmental pressures more frequently than other population groups. In addition, these populations appear to be more sensitive than others to the consequent health effects due to a poorer level of health than the rest of the population and a more random and delayed use of medical care (Dalstra, 2005; Ellison-Loschmann et al., 2007; Crosemarie and Frankreich, 2015). Reducing social inequalities in health and understanding the link between these inequalities and environmental factors is now a specific health policy target in France (law n° 2016-41 January 26, 2016, for the modernization of the French health system).
How are these inequalities integrated within national health and environment policies?
The Public Health Code has implemented a renewable 5-year national plan for the prevention of health risks linked to the environment since the voting of the 2004 law n ° 2004-806 on August 9, 2004. In line with the environmental health strategy (SCALE) developed by the European Commission, the first French national environmental health plan (‘PNSE’) was applied from 2004 to 2008. This finally put the environmental health theme into the public and political arena, thus facilitating its consideration by public authorities and society as a whole. The plan insisted on the need to « develop new methods that make it possible to pool health data with data obtained for environmental factors and population characterization », specifying that « it is necessary to develop approaches that provide a better knowledge of populations (detailed characterizations, definition of populations at risk, etc.), facilitate data spatialization, and enable health actors to measure the phenomena on short, medium and long term time scales » (section 2.3, axis 1). In accordance with the requirements of the Grenelle Environment Law (laws known as Grenelle 1, 2009 and Grenelle 2, 2010), a second PNSE (2009-2013) was then implemented. This project focused on « the consideration and management of environmental inequalities, i.e. limiting any negative ecological impacts that are likely to cause or reinforce health inequalities ». Finally, the third PNSE (2015-2019) concentrated on the need for a better characterization of environmental and territorial health inequalities. It included the development of new scientific concepts, notably the exposome, and sought to strengthen exchanges between the different administrations. Each plan was adjusted within specific regional frameworks called regional environmental health plans (‘PRSE’) that defined targets according to territorial specificities. In this respect, the second regional health environment plan for the Nord – Pas de Calais region (PRSE2, 2011-2014) prioritized the fight against territorial disparities in terms of environmental and social health inequalities.
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