Environment

Last updated on: 04/14/2010

More and more studies and publications have looked at the links between certain types of cancer and hazardous substances or situations present in the environment. Some of these links have been proven, others are currently under investigation and others are based more on feeling and instinct than on scientifically-verified data.
Public health measures have been taken to gain a better understanding of environmental factors and limit their impact.

The role of the environment in the occurrence of cancer: an impact that is difficult to assess.

The media regularly report on new, alarming carcinogenic factors present in our environment. Environmental factors are seen as particularly worrying as they represent a sustained risk, against which people feel powerless. But are current fears about the environment justified? A number of scientific studies have been carried out, looking at the influence of physical, chemical and biological agents that are suspected to cause cancer. Nevertheless, much uncertainty remains. Attempting to prove that a substance is carcinogenic and assessing its impact on the development of cancer is a highly complex task. In fact, it is extremely difficult to isolate the environment as the determining factor in the development of cancer, which can be caused by simultaneous, successive or accumulated exposure to several factors. Furthermore, there may be several decades between exposure to the risk factor and the appearance of the illness. There is also limited knowledge about how to estimate the risk of cancer associated with relatively low-level but chronic risk factors. All these problems are the reason why existing studies have disputed and sometimes contradictory results. Thus, the complexity of the subject matter, the different definitions of the concept of "environment" and scientific uncertainty make it difficult to produce reliable, confirmed figures and can lead to over- or under-estimation of the impact of the environment on the causes of cancer (difficulties linking health-related data and environmental data). In any case, a carcinogenic factor established as such on the basis of a single study cannot be said to be proven definitively. Further in-depth studies are required, to prove or disprove the initial conclusions. Only once converging results have been combined from a sufficient number of studies can a genuine position be taken on the reality of a health-related risk. It remains difficult to prove a causal link between exposure to an agent and the development of cancer in humans, due to the following factors:

• multiple exposures

• difficulty assessing individual levels of exposure
• uncertainties surrounding threshold effects
• the role of individual genetics in cancer susceptibility (including genetic polymorphisms).

Improved knowledge of carcinogenic substances.

Potential cancer-causing agents in humans are now more effectively identified and there are two main classification systems. The international classification created by the IARC (International Agency for Research on Cancer) applies to the environment in its broadest sense and particularly to agents, groups of agents, mixtures and carcinogenic substance exposure situations. This classification acts as a recognised reference framework. It includes some 400 products, classified according to their proven carcinogenic effects on human beings:

• Group 1: Carcinogenic to humans
• Group 2A: Probably carcinogenic to humans
• Group 2B: Possibly carcinogenic to humans
• Group 3: Not classifiable as to its carcinogenicity to humans
• Group 4: Probably not carcinogenic to humans

In Europe, directive 67/548/EEC (relating to the classification, packaging and labelling of dangerous substances) sets out a list of substances classified as carcinogenic, mutagenic and/or reprotoxic (CMR). This regulation, which can be used as a basis for a legal action in Europe, only concerns chemical substances. These substances are classified into three categories, based on the identified risks they pose:

• category 1: substances that are carcinogenic to humans
• category 2: substances for which sufficient information exists to presume that they are carcinogenic but for which there are no human-related data
• category 3: substances that are of concern for humans due to their possible carcinogenic effects but for which insufficient information exists to make a satisfactory assessment.

To date, this classification covers more than 260 chemical substances classified and labelled as CMR category 1 (substances and preparations that have proven CMR effects on humans) or category 2 (substances and preparations that are widely presumed to have CMR effects on humans following exposure and preparations that may cause or increase the frequency of CMR effects). In Europe, the REACH (Registration, Evaluation, Authorisation and Restriction of Chemicals) regulation has been in force since 1st June 2008. This regulation covers more than 30,000 chemical substances and requires in particular:

• the registration of all chemical substances of which more than one tonne is produced or imported per year, prior to their market release
• authorisation for category 1 and 2 CMR (carcinogenic, mutagenic and reprotoxic) substances prior to their market release.

Courses of action to prevent environmental and workplace-related cancers.

Despite the relative uncertainty about certain environmental cancer risk factors (home and workplace), the precautionary principle means that science does not have to provide all the answers before action is taken. In some circumstances, precautionary measures are required to protect populations exposed to suspected carcinogenic agents, even though research has not fully proven the causal link in question. There are two main courses of action to prevent environmental and workplace-related cancer. The first involves improving knowledge and developing scientific monitoring of hazardous substances and their impact on the occurrence of cancer. The second is to develop appropriate regulations and controls to mitigate the risks identified. Where possible, substitute products or processes should be proposed. Over recent decades, collective measures have been taken to limit the population's exposure to carcinogenic substances in the general and workplace environments. These have included reducing pollutant emissions at source, introducing environmental protection measures and developing substitute industrial products and processes. The National Health Environment Action Plan (PNSE 1 and 2) and the Health at Work Plan (PST 1 and 2 currently being compiled) set out the objectives to be achieved in this area. With the establishment of the French Occupational and Environmental Health & Safety Agency (AFSSET), France now has an independent scientific expert body to assess workplace and environmental risks. Finally, the 2009-2013 Cancer Plan includes a number of targeted measures to reduce environmental and workplace-related cancers. Other monitoring initiatives, such as the National Mesothelioma Monitoring Programme (PNSM), have been introduced.

The "Grenelle Environnement" round-table debate

In May 2007, the French President launched the "Grenelle Environnement". This round-table debate took place in June 2007, bringing together the government and civil society representatives. The purpose of this initiative was to create a road map for environmental protection and sustainable development. Six working groups were created, with the third focusing on "creating a healthy environment". Following the work carried out in these groups, four round-table discussions were held and the key areas of action for all topics were determined. The "Health and Environment" round-table discussion recommended the following actions: forbidding the sale of phytosanitary products containing extremely worrying products for domestic use or use in public places

• reducing total emissions of certain substances (benzene, tetrachloroethylene, trichloroethylene, etc.)
• creating inter-regional and multi-disciplinary research and expertise centres to investigate the links between health and the environment
• monitoring the population, beginning with the most vulnerable people, creating cancer records and setting up health and environment consultation processes to open the way for at least partial support for the most vulnerable people
• in 2008, jointly defining a National Health Environment Action Plan 2 for 2009-2013
• improving outdoor and indoor air quality
• adapting observation and health monitoring practices to emerging risks
• introducing an obligation to declare the presence of nano-particles in consumer products.

Following this work, the government compiled the "Grenelle 1 white paper", which was adopted by the French parliament in July 2009. Following the PNSE 1, the PNSE 2 (2009-2013) was presented to the Council of Ministers on 24th June 2009. It comprises 16 sheets and 58 actions, which include reducing emissions of toxic particles and substances into the air and water, improving indoor air quality, protecting the population from water-related environmental contamination and reducing exposure to naturally-occurring radon and asbestos. A plan monitoring committee was set up on 22nd October 2009. This committee is chaired by Bérangère Polleti, member of parliament for Ardennes and brings together representatives from the five colleges of the Grenelle Environnement, key figures and professionals from the world of healthcare and the various institutes and agencies concerned. It is responsible for creating an annual plan progress report and proposing recommendations to improve the implementation of and expand the plan, based on new knowledge about environmental health risks.