Cyclist in London

In 1989, the first Ministerial European Conference on Environment and Health adopted The European Charter on Environment and Health, stating that:

Good health and well-being require a clean and harmonious environment in which physical, physiological, social and aesthetic factors are all given their due importance. The environment should be regarded as a resource for improving living conditions and increasing well-being.

(WHO, 1990)

This basic statement results from a self-evident but often neglected fact that human health depends on the availability and quality of food, water, air and shelter. It is a basic requirement of health that the global cycles and systems on which all life depends are sustained. The potential of the environment to have adverse effects on health has been realised for centuries. However, in recent years, public awareness of environmental health hazards has increased. This has been due, in part, to the rapid development of industry and new, potentially hazardous, technologies. The progress of scientific research revealing the existence of previously undetected hazards, which may have been present for some time, has also increased public concern.

This chapter summarises the information on the main issues related to the health status of the European population and on known links of health with environmental conditions in Europe. It is derived from material presented in the report Concern for Europe's Tomorrow (CET) (WHO, in press). The main objectives of the CET report are the evaluation of the environmental issues of clear health significance, the assessment of European population exposure to the environmental factors possibly affecting health, and the indication of health impacts of these factors.

The scope of the CET report is determined by the definition of health adopted by WHO, which states that

'Health is a state of complete physical, mental and social well-being and not merely the absence of disease or infirmity.'

In the description of health status of the European population presented in the CET and summarised here, a major limitation is the difficulty in providing a proper measurement of health. Mild deficits of health are very subjective; small physiological changes can be measured but their health significance, for example, as predictors of a disease, is not always clear. More serious health deficiencies, even those requiring treatment, are rarely recorded in a way enabling inference about the population health status. Epidemiological studies are necessary to establish prevalence of certain diseases, but the availability of such studies in Europe is very limited due to the costs and resources needed to conduct this type of research. For this reason most of the information on health status is based upon the registration of death ­ the most severe health deficiency. Mortality data have been collected in all European countries for many years and recorded according to a uniform classification of causes of death. Total and age-specific mortality data, combined with information on age structure of a population, serve to calculate that widely used demographic indicator, 'life expectancy'.

Life expectancy and cause of death constitute the basis for the descriptive analysis of the main aspects of population health status in Europe presented below. The latest data available relate to 1990, and to the countries existing in 1990. For the indices of health status available for all, or most, countries, the results of national data analysis are presented for three groups of countries: countries of Central and Eastern Europe (Poland, East Germany, former Czechoslovakia, Hungary, Romania, Bulgaria, former Yugoslavia), former USSR (including its parts of Asia), and the remaining countries hereafter referred to in this chapter as 'Western Europe' or 'European OECD countries'. This grouping is dictated largely by the available statistics which, for example, do not separate data related to European and non-European parts of the former USSR. However, the relative homogeneity of the mortality patterns within these three groups allows for this kind of classification. Whenever possible, the descriptions based on mortality data are supplemented by information from epidemiological studies evaluating less severe health deficiencies. Further, the known health hazards of specific environmental media and factors are reviewed, and their possible impact on health in Europe is evaluated. These descriptions are preceded by a short summary of issues to be considered before the links between health and environment are assessed.

Humans are exposed to a variety of environmental factors through air, water and other beverages, food, and materials that contact the skin. Exposure occurs in a variety of settings: residential, industrial, occupational, during transport, and both indoors and outdoors. Exposure occurs when there is contact between a person and an environmental factor. The degree of exposure depends on the specific concentration or intensity of the factor and the time interval. Consideration of exposure to environmental factors is crucial to assessing their potential health effects. Occasional contact with a contaminant may have negligible effect, while prolonged contact with the same factor may have serious, though in many cases non-specific, health impacts. If a factor is present in various environmental media, the exposure of an individual occurring from each of these media accumulates (determining total exposure). This must be considered when preventative measures are designed, to evaluate both costs and the effectiveness of reducing total exposure when the factor is eliminated from one medium only. Exposure, together with the capacity of the organism to absorb, distribute and metabolise the factor, determine the individual's internal dose. This influences the likelihood, type and intensity of health effects.

Adverse health reactions to an exposure may take a whole range of forms, extending from a disturbance of aesthetic values or psychological and physical discomfort, through physiological changes of uncertain health significance, to varying intensity of clinical disease from mild to severe or, in an extreme, uncommon case, to a disease leading to death. A number of health effects become apparent after a delay (latency period for some cancers is as long as 20 years or more) and, in some cases, an exposure accumulated only over several years produces a disease. An individual's response to environmental exposure may be related to personal (including genetic) susceptibility. For example, the effects of air pollution on the respiratory system are different in people with a pre-existing disease (for example, with asthma) than in healthy subjects. Personal behaviour may modify the extent of exposure or the dose of an environmental factor: exercise increases respiration rate and the amount of an air pollutant absorbed; children playing in a sandpit contaminated with lead, or licking walls covered by lead-containing paint, increase their exposure to lead. Synergistic effects may also occur. For example, the risk of lung cancer related to asbestos in air increases ten-fold in people smoking cigarettes as compared with non-smokers. Nutritional status may also modify the response to an environmental agent.

The assessment of the health hazard of an exposure is based upon toxicological evaluation of the factor, which can involve the assessment of health effects of a controlled exposure in a group of animals or humans, usually to relatively high levels of the factor. An assessment of the actual health risk due to the presence of the hazard in the environment is based on the information concerning the population exposure to the factor and on the knowledge of the exposure­response relationship. Epidemiological studies are an important source of this information. In these studies, the relationship between an environmental factor and a disease, or other health parameter, is assessed taking into account possible influences of other factors on the relationship. This approach is extremely important since, in most cases, the diseases in question are of multifactor aetiology, that is, they may be associated with a variety of factors and their interactions. In spite of a development of epidemiological methodology in the last decades, the quantitative assessments of many health­environment relationships are still incomplete, and the uncertainty of the risk estimates is rather substantial. In part, this is due to incomplete knowledge concerning the health effects of exposures of low intensities occurring in the environment. Also, sufficiently precise assessments of environmental exposure are lacking for most of the European population. Improvements in both require substantially increased resources and expenditure. The estimates of health effects of the environment in the European population summarised below thus have a large margin of uncertainty.

It is important to stress that the environmental health policy should focus on prevention of exposure to the environmental hazards and on the avoidance of health effects in the population. Air, water and food quality standards and guidelines have been prepared by national and international bodies with the purpose of protecting the health of the population. Guidelines are set according to the agent, mode of exposure and health effect, and the consequence of the exceedance of one is difficult to compare with another. Furthermore, exceedance of a guideline does not directly imply the immediate onset of a health effect. In populations this relationship is usually better described as a continuum, where the guideline figure represents a value above which the probability of the onset of a health effect is regarded as undesirable given the nature of the exposure and uncertainties related to the estimation of this figure. Taking into account the inherent uncertainties of the risk assessments leading to guideline setting, the adoption of the precautionary principle of preventative action is advisable.

In most European countries, the public health services have succeeded in identifying, regulating and controlling many of the factors potentially affecting health. Analysis of population exposure to environmental hazards and of population health status may indicate areas where the risk to health is still significant, and where more intensive action of the involved economic sectors, environmental health authorities and society is needed. A factor-by-factor approach should be supplemented by a comprehensive assessment of the combination of environmental, occupational, lifestyle, social and personal factors. It is quite common that selected parts of society, frequently the poorest or most underprivileged members, are exposed to multiple hazardous environmental conditions (see, for example, Chapter 10). The health impact of such combinations may significantly exceed the estimates based on evaluations of individual factors.

Perhaps the simplest indicator of population health is based on self-assessment of health evaluated in population surveys. These data, available from 14 European countries (WHO, 1991), show that the residents of Sweden and Norway are the most satisfied with their health, with 95 per cent of people assessing their health to be fair or average, or better. The worst scores were reported from Poland and Hungary, where the above proportion does not exceed 80 per cent. In all countries, except Finland, the proportion of males rating their health as good is higher than that of females.

The life expectancy at birth in European countries was 74.9 years in 1988. It ranged from 69.3 to 78.2 years, with a clear tendency for the lowest values to occur in Central and Eastern Europe (Figure 11.1). Over the 1980s, there was a steady increase of average life expectancy (from 73.2 years in 1980, or 0.2 years annually). This was a continuation of the average trend observed over the previous decade. However, most of the countries with low life expectancy at the end of the 1980s have shown very little improvement in the past ten years.

In contrast to male perceptions in assessing their health, life expectancy in females is actually greater than that in males: the average difference is about 6.8 years (ranging from 3.7 to 8.8). Large differences are found in countries with overall life expectancies which are relatively high (France) and low (Poland, Hungary). Only about one third of countries in Europe have shown small reductions in this difference after 1980. For the others, the difference is stable or still increasing.

Infant mortality, that is, deaths of children before one year of age, has an important impact on the life-expectancy-at-birth indicator. This indicator improved in all countries of Europe, declining from an average of 16.0 per 1000 live births in 1980 to 10.8 in 1989. Twenty-one per cent of the total increase of average life expectancy at birth between 1980 and 1989 can be attributed to the reductions in infant mortality. The rates of decline in infant mortality were similar in the Western and Eastern parts of Europe, with the result that the pattern of substantial differences between countries was maintained. In 1988­90, the highest rates (22 to 27 per 1000) were noted in Romania, Albania, former Yugoslavia and the former USSR, and the lowest (below 6 per 1000) in Iceland, Finland and Sweden. The most significant contribution to the infant mortality difference observed between various parts of Europe is the number of deaths due to communicable diseases. Their frequency ranged from 0.4 per 1000 live births in Western Europe, through 4.7 in Central and Eastern European countries, to 9.2 per 1000 in the former USSR. This can be attributed, at least in part, to poorer sanitary conditions of human settlements (eg, lack of piped water supply at home) in the Eastern part of the region. A study conducted in the Czech Republic has detected an increase of infant mortality, and in particular of the post-neonatal mortality due to respiratory diseases, in regions with elevated concentrations of suspended particulates in the air (Bobak and Leon, 1992). Though the observed association has yet to be confirmed by other studies, the possibility of a causal link between infant health and air pollution cannot be excluded.

Similarly to life expectancy at birth, life expectancy of people at ages after infancy, on average, increased in Europe during the 1980s. However, a clear difference in trends can be seen when countries are divided into groups. Whereas in Western European countries the life expectancy at ages 1, 15, 45 and 65 displayed a steady increase over the decade, there was a stagnation of the indicators in Central and Eastern Europe, and even a decline in the former USSR.

The above difference in trends of life expectancy between the groups of countries is due to differences in trends of age-specific mortality. In Western Europe, mortality has declined in all age groups, with approximately constant rates in the 1970s and 1980s. Mortality in the remaining countries of Europe followed this pattern until the mid-1970s (though on a higher absolute level). However, in the following years, in Central and Eastern Europe, the decline of mortality was much smaller or remained static, and in males aged 15 to 64 years there was an increase in the 1980s (Figure 11.2).

When the mortality at all ages is considered, the most common causes of death at the end of the 1980s were diseases of the circulatory system (42 per cent of all deaths in Western Europe, 55 per cent in Central and Eastern European countries, and 58 per cent in the former USSR), followed by cancers (25, 17 and 16 per cent, respectively) (Figure 11.3). The third leading group of causes of death was injuries and poisonings (6 to 9 per cent), followed by respiratory diseases (6 to 7 per cent). Communicable diseases were a relatively infrequent cause of death, responsible for approximately 1 per cent of all deaths, although the rate was twice as high in the former USSR as in Western Europe. In all parts of Europe, mortality due to communicable diseases halved over the last two decades.

The structure of causes in total mortality reflects, to a large extent, the relative frequency of diseases in the oldest age groups. In age groups below 45 years, the structure of causes of deaths is different. Among young males, close to 50 per cent of all deaths are due to injury and poisoning. Also among young females, fatal accidents are a very common cause of death (24 to 33 per cent of mortality) but in the 15 to 44 age bracket, in all countries except the former USSR, neoplasms are the leading cause of female death (29 to 33 per cent).

The main group of causes of death responsible for the difference in trends between the Western and Eastern parts of Europe were the circulatory system diseases. A steady decline of this mortality was observed in Western countries throughout the 1970s and 1980s, while an increase or, at best, stabilisation of rates was seen in Central and Eastern Europe. At the end of the 1980s, there was a more than two-fold difference in rates between the groups of countries in people aged 15 to 64 years, and a 70 per cent excess of mortality in Central and Eastern Europe compared with Western Europe in the oldest age group. The prevalence of cardiovascular diseases, assessed in population studies in some European countries, is also higher in the Eastern countries than in the West. The main recognised risk factors of cardiovascular diseases, and coronary heart disease in particular, are hypertension, high cholesterol levels and smoking. Less clear are the roles of obesity and inadequate physical activity. Diet, especially the intake of saturated fats and salt, can have an impact on the risk factors and, indirectly, on disease. There seems to be a rather limited relationship between cardiovascular diseases and environmental factors, although adequate environmental conditions (housing, work, recreational facilities) can influence behaviour and healthy lifestyles, and, indirectly, can modify the risk of cardiovascular diseases. Potentially, increased levels of carbon monoxide in air, due to traffic emissions (eg, in traffic tunnels) or fossil fuel combustion indoors, can aggravate arrhythmia or angina symptoms in patients with cardiovascular disease.

The differences of mortality due to malignant neoplasms (cancers) in various parts of Europe are less dramatic than those for cardiovascular diseases. In the late 1980s, in age groups below 65 years, this mortality was higher in Central and Eastern Europe by up to 25 per cent, or 50 per cent in the former USSR, than in the rest of the continent. This was the result of a combined effect of an increasing trend in Central and Eastern countries accompanied by a decrease of the rates in Western Europe. In people 65 years of age and over, cancers were 25 per cent more commonly diagnosed as a cause of death in Western Europe than in Central and Eastern parts, and the rates changed very little during the last two decades. A detailed analysis of spatial patterns of cancer mortality at sub-national level was conducted recently for EU countries (Smans et al, 1992). The known differences in diagnostic and coding practices may bias the comparisons. However, some spatial trends, for example lower mortality rates for many cancer sites in the south of Italy than in the centre or north, may be at least partly real. At present, it is difficult to find a convincing explanation for these differences.

Although the aetiology of most cancers is still obscure, several risk factors have been identified. Tobacco smoking undoubtedly increases the risk of lung cancer (85 per cent of all cases in men are attributable to smoking) and also of several other cancers (oesophagus, oral cavity, pharynx, larynx, bladder, kidney). Dietary factors are suspected to be related to digestive tract cancers. For stomach cancer, a diet rich in starchy food as well as smoked, salted and fried foods is suspected to increase the risk. High intake of fat is suspected to increase risk of colon and rectum cancers. Diet rich in vegetables, citrus fruit and fibre may reduce the risk. Various hormonal factors may increase the risk of breast, corpus uteri and prostate cancers. A sexually transmitted human papilloma and other viruses are suspected as risk factors for cervix uteri cancer, and chronic hepatitis B virus infection increases liver cancer risk. Various chemicals present in the environment are known to have carcinogenic properties, for example: benzene, soots, arsenic and its compounds, asbestos, nickel compounds, radon and its decay products. In most cases, the population exposure to these substances is rather limited and a quantitative assessment of the contribution of environmental exposures to total cancer incidence is difficult. However, as discussed further in this chapter, some components of urban air pollution, selected occupational exposures and ionising radiation have been shown to increase incidence of, and mortality from, lung and other cancers in the European population.

The main inter-country differences in mortality due to respiratory system diseases are as a result of mortality in children. In the former USSR, death rates (mainly from pneumonia and acute respiratory infections) exceeded those in Western Europe 20-fold, and those in Central and Eastern Europe, three-fold. In people 15 to 64 years of age, mortality due to respiratory diseases steadily decreased in Western Europe over the last two decades but was stable, or decreased much less, in Central and Eastern Europe. The differences in trend were greater in males than in females. As a result, by the end of the 1980s, the rates differed two-fold between Eastern and Western Europe, although they were similar 20 years earlier. In people 65 years of age and older, where chronic respiratory diseases are dominant, the rates and trends in mortality were similar in all parts of the region, and decreasing. Data from population studies indicate that close to 10 per cent of the adult population may suffer from chronic respiratory diseases. Since these diseases may severely restrict normal activity of people for decades of their life, the public health significance of chronic respiratory diseases is greater than that indicated by the proportional mortality rates. Besides tobacco smoking, which is probably the main risk factor of chronic obstructive airways disease, air pollution (outdoor and indoor, both occupational and residential) may play a significant role in their aetiology. Host factors (for example, bronchial hypersensitivity) are important risk factors for the asthmatic form of the disease.

Declining mortality from tuberculosis of the respiratory system is a main cause of the diminishing mortality brought about by communicable diseases in Europe. The incidence of these diseases was markedly reduced in recent decades in most European countries. However, epidemics of some communicable diseases are still observed in selected regions. An example is the dramatic increase of diphtheria incidence (eliminated from a number of European countries) in some parts of the former USSR during 1991­92. High incidence of hepatitis B and tuberculosis is also observed in some countries (Romania, Bulgaria, the former USSR, Poland). The aetiology of most of the communicable diseases is well understood and many of them are related to basic environmental conditions, for example: proper water sanitation, communal waste disposal, hygienic housing conditions, food processing and storage. These factors may have the most pronounced impact on the occurrence of the communicable diseases in infants, and on infant mortality, as mentioned above. Lifestyles, as well as the availability and effectiveness of preventative measures (eg, vaccination) are important factors related to the incidence of some of these diseases.

The AIDS epidemic increased rapidly in Europe up to 1990. The rate of increase in the number of new cases diagnosed was slower at the beginning of the 1990s than in the previous decade, but the incidence is still growing. Over 95 per cent of European cases have been registered in Western Europe.

Mortality due to injury and poisoning has, on average, declined in Europe over the last two decades but the rates in Eastern Europe remain double those in Western countries. Substantial variability of the rates is seen between countries, also within particular parts of Europe. The main cause of accidental deaths was motor vehicle traffic accidents (in various countries, from 21 to 52 per cent of male, and from 11 to 50 per cent of female, deaths in accidents) and suicide (from 7 to 71 per cent). The number of casualties from road traffic accidents (over 350 people killed and 6000 injured daily in Europe) exceeds by several orders of magnitude the number of victims of other types of accidents or emergencies. Accidental poisonings are not a common cause of death in most countries, accounting for 3 per cent of male and 5 per cent of female accidental deaths in Western Europe, 8 and 6 per cent respectively in Central and Eastern Europe, but as much as 21 per cent in the former USSR. The important characteristics of mortality due to accidents, and mortality due to traffic accidents in particular, are their similar intensity in all ages over 15 years; this is in contrast to deaths due to the remaining causes, where the rates in the oldest age groups exceed those in young adults by two orders of magnitude. As a result, the proportion of deaths due to accidents in young people is relatively high (reaching 19 per cent of all deaths in males 15 to 44 years old in Western Europe, and 12 to 14 per cent in the remaining parts of Europe), and the social costs ('years of life lost') are very significant. Even higher are the costs of a larger number of non-fatal injuries resulting from traffic accidents, involving temporal or permanent restrictions of human activity and disability. Traffic accidents are, at least in part, due to inappropriate development of the transport networks and their associated infrastructure, an integral part of today's urban environment (see Chapters 10 and 21).

The CET analysis (WHO, in press) of exposure of the European population to environmental factors, and of the health significance of the exposure, has been carried out in the context of a lack of detailed and comprehensive studies of health effects due to environmental factors in Europe. The CET was compiled in order to obtain an idea of the situation in Europe, recognising from the start that few reliable data are available on which to base extrapolations, and that there will be errors in the assessment of numbers of people allocated to a particular exposure level. The unsatisfactory nature of the available information arises not only from problems of data collection but also from the complexity of health­environment relationships per se, and the number of confounders to understanding the true causes and effects.

Not withstanding these important caveats, the results of the CET confirm that a considerable proportion of the European population is exposed to environmental factors to an extent which is considered to pose a threat to some aspect of health. The precision of the estimates is limited, and the large errors which may be associated with them will be due mainly to the incompleteness of the data on population exposure to particular factors. The results presented below represent the best estimates currently available; nevertheless, the figures should be interpreted with caution.

The most common environment-related health problems concern exposure to excessive levels of air pollutants, possibly affecting hundreds of millions of people in Europe. In most cases, the exposure relates to urban populations and occurs in short episodes. In the past decade, many epidemiological studies have observed health effects related to this type of exposure, for example, in Athens, Barcelona, Cracow and several French and German cities. Some of the cities where the concentrations of the most commonly monitored air pollutants exceed WHO air quality guidelines are listed in Chapter 4. Among the air pollutants considered, particulate matter (PM), measured as 'total suspended particulates' (TSP) or black smoke, is estimated to pose the greatest potential burden to health. An example of the results supporting this conclusion is the proportion of chronic respiratory diseases expected to be related to PM: as many as 15 per cent of asthma cases and 7 per cent of obstructive airways disease (OAD) occurring in the urban European population (at least 18 000 cases a year of each disease) are estimated to be possibly related to prolonged exposure to high concentrations of particulates. In cities with the highest dust concentrations, the proportion of cases attributable to pollution reaches 23 per cent of asthma and 11 per cent of OAD cases. Among other health problems expected to be caused by excess PM and affecting a considerable number of Europe's residents are various short-term respiratory symptoms and diseases, chronic and transient decrements of lung function, and even precipitation of mortality. Various respiratory problems, some requiring hospitalisation, are estimated to be related to ambient air pollution characterised by elevated levels of sulphur dioxide (SO₂) and nitrogen oxides (NO_x). Up to 30 per cent of the European population may experience these pollutants in concentrations exceeding daily WHO air quality guideline levels, though for most of these people the exposure is limited to less than 30 days per year. Exposure to elevated ozone levels, though affecting a very large part of the European population, seems to produce less severe health effects, such as transient decrements in lung function (especially in children or in exercising people), cough or eye irritation episodes.

Indoor air pollution was also considered as an important factor. Examples of the most common types of indoor air pollutants are carbon monoxide (CO) and nitrogen dioxide (NO₂) generated by indoor combustion sources (eg, unvented gas stoves), tobacco smoke, volatile organic compounds emitted from building materials or consumer products (eg, paints and cleaning agents), radon and its decay products (see below), and asbestos fibres. Population exposure to these pollutants is very heterogeneous and depends on a variety of factors, including the geological structure of the soil under the building (radon), the construction of the building (ventilation rates, building materials) and personal behaviour (use of pollutant emitting agents, presence of smokers, time spent in various indoor spaces). The assessment of such exposures is thus an extremely difficult task and is not available for most of the European population. Consequently, the possibility of a quantification of the health impact of indoor air pollution is very limited. However, the risk due to the exposure to several indoor air pollutants is established relatively well. For example, the risk of lower respiratory tract disease in infants exposed to tobacco smoke due to a mother smoking at home is increased by some 50 to 100 per cent, according to a recent comprehensive review (USEPA, 1992). The risk of respiratory disease may be increased by some 20 per cent due to nitrogen dioxide exposure associated with the use of gas stoves at home, as indicated by combined evidence from several studies (Hasselblad et al, 1992).

Besides the acute or chronic respiratory system diseases, which are the most common health effects of air pollution, some components of urban or indoor air pollution may increase the risk of cancers. For instance, asbestos, benzene and soots are classified by the International Agency for Research on Cancer as 'carcinogenic', and benzo[a]pyrene and diesel engine exhausts as 'probably carcinogenic'. The limited database, however, does not allow an accurate quantification of the potential impact of present ambient air pollution on cancer incidence in Europe; only site- and case-specific conclusions can currently be drawn. An epidemiological study conducted in Cracow, Poland, has shown an increase in lung cancer risk in residents of the city centre which, especially in the past, was heavily polluted (Jedrychowski et al, 1990). The main source of pollution was combustion of coal for heating. Also, there is evidence for increased lung cancer risk in the populations surrounding some types of industry, in particular non-ferrous smelters, where arsenic emissions may be of importance (Pershagen and Simonato, 1993). Better established than the impact of ambient air pollution on cancer is the relationship between the risk of cancer and indoor air pollution. In particular, there is sufficient evidence to expect a 20 to 30 per cent increase in risk of lung cancer in non-smokers married to smokers, related to the environmental tobacco smoke exposure (Pershagen, 1993).

Contamination of drinking water and food with microbiological agents can be a source of a variety of communicable diseases, such as hepatitis A, salmonellosis or shigellosis. Though the contamination sources, routes of transmission and preventative measures are, in general, known, there is evidence that the protection of the population is not sufficient in several areas of Europe (WHO, in press). Outbreaks of diseases due to microbiological contamination of drinking water have been reported in the UK, France, the Russian Federation, former Yugoslavia, Romania and Scandinavian countries. Microbiological contamination of bathing water, mainly in the Mediterranean, is estimated to result in over two million cases of gastrointestinal diseases annually. Potential health hazards of chemical water pollution are also significant. Predicted nitrate concentrations of groundwaters in several areas across Europe with intensive agriculture were found to exceed guideline levels designed to protect infants from methaemoglobinaemia, a serious, life-threatening disease (see Chapter 5). Concentrations of arsenic found in waters of selected regions of Bulgaria, Hungary and Romania can also, potentially, lead to health problems (skin cancer). In Estonia, high levels of fluoride have been observed and were found to cause endemic fluorosis. However, most of the hazardous chemicals are effectively regulated and controlled, and the exposure to chemicals in drinking water seems, generally, to have less health impact on the total population of Europe than does the microbiological contamination. The data on the local situations, where the exposure may indeed pose a health risk, are very scarce and this hampers a more precise estimation of the potential problem.

From a variety of pollutants to which an exposure may occur through various media, lead is identified as a substance posing a health risk in several regions of Europe. The available data indicate a substantial decrease in exposure to lead in a number of countries in Western Europe over the last decade, due mainly to the reduced quantity of lead in petrol. However, in selected locations in Central and Eastern Europe, mainly around lead-emitting industries (eg, Hungary, Romania), the measured population exposure to lead is still high, possibly resulting in impaired mental development of children and in behavioural problems. It is estimated that at least 400 000 children in Eastern parts of Europe may be affected.

The main source of population exposure to ionising radiation is naturally occurring radon and its decay products (Chapter 16). The populations most at risk are miners and residents of particular areas where radon is emitted naturally from the soil. According to the existing data (WHO, in press), approximately 2 million people in Europe are estimated to be at elevated health risk from this cause. The main health effect of ionising radiation is neoplasms. Recent studies from Finland, Norway and Sweden indicate that as many as 10 to 20 per cent of all lung cancer cases in these countries can be attributed to residential radon exposure (Simonato and Pershagen, 1993). For the EU it is estimated that up to 10 000 cancer deaths (ie, 1 per cent of all cancer deaths) are caused annually by radon (Trichopoulos and Karakatsani, 1993).

Experimental evidence indicates that the ultraviolet part of solar radiation (and its shorter-wavelength part, UV-B, in particular) is a risk factor of skin cancer (IARC, 1992) (see Chapter 16). Also, UV-B is a recognised risk factor for cataract, and it is suspected that UV-B may suppress normal immune responses. It is estimated that the increase in terrestrial levels of UV-B by 1 per cent, related to stratospheric ozone depletion, may result in 1 to 2 per cent excess in the health effects. However, the assessment of a possible increase of cancer or cataract cases in Europe due to UV-B exposure is difficult to evaluate because of the insufficient precision of the disease registers, lack of exposure data and the possible influence of personal, or genetic, characteristics on the dose­effect relationship (see Chapter 28). Furthermore, many of the potential hazards of UV-B can be eliminated by individual conduct, for example by avoidance of excessive exposure to sunlight.

The potential health risks related to the relatively widespread exposure to low-frequency (50 to 60 Hz) high intensity electromagnetic fields is still being investigated and no conclusive evidence is available (Draper, 1993) (see Chapter 16).

Waste collection and disposal and treatment procedures are a potential health hazard because wastes can, in principle, contain any hazardous chemical, biological and physical agent. Through an emission to ambient air or leakage to surface and groundwater, the environment surrounding a waste site can be biologically or chemically contaminated (see Chapters 7 and 15). Several technical and organisational means can (and do) minimise or even eliminate the waste-related threats to human health. Studies conducted to evaluate health impact of waste sites have failed to provide conclusive evidence of a causative role of waste sites in the incidence of more serious health effects (such as cancers, reproductive outcomes). In part, this may be due to considerable methodological difficulties faced by the studies, mainly in obtaining adequate data on exposure to relevant pathogenic agents. However, increased anxiety, diarrhoea and reports of disturbing odours have been registered more often in populations living in the vicinity of these installations than in the control groups (WHO, in press). Notwithstanding lack of epidemiological evidence ­ potential, present and future ­ more serious health impacts of the poorly managed or uncontrolled waste sites should not be understated.

For human health, housing conditions are a very important element of the environment. To a large extent, they depend on the type and status of urban development, described in detail in Chapter 10. Among the main factors affecting health, deficiencies in sanitary equipment of houses were identified by the CET project as the most significant. Poor sanitary conditions (eg, lack of piped water supply at home) increase the risk of communicable diseases. Improper housing conditions may result in exposure of the residents to hypo- or hyperthermia and, in the case of insufficient ventilation, to indoor air pollutants, with some of the health consequences summarised above. An example of the effect of insufficient ventilation in newly built, air-tight buildings is the growth of mite allergen, possibly promoting allergic sensitivity among residents, observed in cold parts of Sweden (Wickman et al, 1992). Approximately 40 000 fatal accidents are estimated to occur annually in houses in Europe, although it is difficult to assess the proportion of these accidents related to unsafe housing conditions or faulty design, construction or maintenance. The number of less severe accidents, resulting in an injury, is expected to be a hundred times greater. Physical or psychological discomfort or stress (for example, caused by excessive noise ­ see Chapter 16 ­ estimated to affect a quarter of the European population) are also adverse health effects related to deficient housing conditions and, sometimes, to improper urban planning and development.

Health effects of occupational factors, in contrast to other environmental exposures, can usually be anticipated in certain types of industries or workplaces. Appropriate preventative measures can reduce health impacts of inherently harmful types of manufacturing or other work-related human activities, though it is rarely possible to eliminate some of these hazards completely. As a consequence, the impact of unhealthy working conditions is still significant in the European population. Probably the most acute are accidental injuries, experienced by 25 per cent of workers in high risk occupations (construction, mining, fishing), resulting in approximately 25 000 deaths annually and causing permanent disability with a rate of between 20 to 30 per 100 000 people (ILO, 1992). It is estimated that between 1 and 20 per cent of all cancers are work-related. The rates of chemically induced occupational diseases decreased in recent years due to increased awareness of the hazards and as a result of preventative measures. However, differing degrees of sophistication of occupational health and safety legislation result in large differences between countries.

The significant figures from road traffic accidents dominate accident casualty statistics, for which the road traffic environment is certainly partly responsible. Next to this, the health effects of industrial and nuclear accidents, or biological contamination of food and drinking water, can be documented by hundreds of fatalities and thousands of injured or sick registered annually in Europe and ascribed to a known, though unexpected, event. Between 1980 and 1991, over 1100 people were killed in major chemical accidents which occurred in Europe and were registered by the OECD. Many of the most serious accidents were related to the transport of gas, oil or chemicals, including transport by pipelines. The spectrum of health problems of the accidents covers a wide range of acute effects ­ injuries, burns, poisonings ­ as well as long-term, or delayed, outcomes, including increased risk of neoplastic diseases or of congenital malformations in children of exposed parents. Mental health can also be affected by the event and the emergency situation (see also Chapters 18 and 30).

Although the dominating risk factors of the most frequent severe diseases are related to various host characteristics (eg, genetic predisposition or other individual susceptibility) or behavioural and lifestyle factors (eg, tobacco smoking, diet, excessive alcohol drinking), a number of environmental factors may, and probably do, adversely influence the health of the European population. The analysis conducted for the CET report (WHO, in press) focuses on the observed or observable effects, that is, changes in health occurring immediately or shortly after an exposure to an environmental agent. Small physiological changes, possibly related to prolonged exposures of low intensities and especially to combination of exposures, may accumulate and result in an emergence of adverse health effects in the long term. At present, a number of the basic health indicators (life expectancy, mortality, incidence of communicable diseases) show positive changes. One can assume that these positive changes are due largely to alterations in lifestyle and improvements in medical care, but they may also result partly from improvement in living and environmental conditions (improved sanitation, safer working conditions, reduced air pollution, and better housing preventing overcrowding and the influence of adverse climatic conditions). Deviations of health indicators from these positive trends observed in some parts of the European population should be of significant concern and a reason for comprehensive responses. Besides the promotion of healthy lifestyles, these should aim at creating an environment which promotes health. Effective prevention or reduction of population exposures to the recognised health hazards should be of the highest priority. An important condition of effective preventative action and management of the environmental health risk is the ability to assess the risk properly. This requires adequate support by environmental health research and monitoring and, in particular, European-wide epidemiological studies.