Unit 1
Environment and Human Health

Learning Outcomes

Prerequisites

Key words

Health, Environmental Quality, Environmental Diseases, Environmental Degradation, Occupational Health Hazards

Discussion

How is human health related to the environment? What are the different environmental factors that affect human health?

3.1.1 Environment and human health

Human health and well-being are intimately linked to the state of the environment. Good quality natural environments provide basic needs, in terms of clean air and water, fertile land for food production, and energy and material inputs for production. Environmental degradation can have a significant impact on human health. Although the environment sustains human life, it can also cause diseases. Lack of basic necessities is a significant cause of human mortality. Environmental hazards increase the risk of cancer, heart disease, asthma, and many other illnesses.

Natural environments provide numerous challenges to human health and well-being, and many of these challenges are continuing to grow and develop, both in ways that we can-reasonably forecast and ways that we cannot. Moreover, social and economic factors mean that different segments of society are affected n differing ways and to varying degrees. The natural environment contributes significantly to people‘s health through the quality of air we breathe, the food we eat and the water we drink. On the one hand, it offers health enhancing economic and recreational opportunities, while on the other, it is threatened by activities such as transport, industrial processes, and agricultural and waste management practices. Environmental pollutants and potentially pathogenic organisms can harm people‘s health through a series of complex transport and exposure pathways.

Global climate change will have a wide range of health impacts. Overall, negative health impacts are anticipated to outweigh positive health impacts. Some health impacts would result from changes in the frequencies and intensities of extremes of heat and cold and of floods and droughts. Other health impacts would result from the impacts of climate change on ecological and social systems and would include changes in infectious disease occurrence, local food production and nutritional adequacy, and concentrations of local air pollutants and aeroallergens, as well as various health consequences of population displacement and economic disruption.

3.1.2 Impacts of environmental degradation on human health

Natural environment degradation refers to the destruction and loss of native species and natural processes such that only certain components of the original biodiversity and ecological functions persist, often with significantly altered natural communities. Environmental degradation is the disintegration of the earth or deterioration of the environment through the consumption of assets, for example, air, water and soil; the destruction of environments and the eradication of wildlife. There is growing concern about the links between the environment and health. Many factors influence the health of a population, including diet, sanitation, socio-economic status, literacy, and lifestyle. A person is exposed to many environmental factors within his/her local environment: chemical emissions from consumer products (particles, air pollutants), environmental noise, moulds etc. Humans need to interact with the environment to obtain our food, water, fuel, medicines, building materials and many other things. Advances in science and technology have helped us to exploit the environment for our benefit, but in the other side, as a result of human inter-ventions, pollution becomes a major concern and caused environmental damage. Vulnera-bility and exposure, however, vary marked-ly between different groups and areas, with children and the elderly being particularly at risk. There is reasonable understanding of cause-and effect relationships between water, air pollution and human health. However, the health consequences of other environmental factors and exposures, such as those resulting from climate change and chemicals in the environment are less understood. The environment directly affects health status and plays a major role in quality of life, years of healthy life lived, and health disparities. Poor air quality is linked to premature death, cancer, and long-term damage to respiratory and cardio-vascular systems. Second-hand smoke containing toxic and cancer-causing chemicals contributes to heart disease and lung cancer in non-smoking adults. Globally, nearly 25% of all deaths and the total disease burden can be attributed to environmental factors. Poor environmental quality has its greatest impact on people whose health status is already at risk.

3.1.3 Environmental Health Hazards

Health has benefited greatly from development, and industrialization in particular, as well as from increased societal and personal wealth, substantially improved transportation, and enhanced health and education services. Without a doubt, compared to centuries or even decades ago, people are living longer and are healthier on a global basis. Industrialization has, however, had negative health effects on the population as a whole as well as on the workers. These impacts have been brought on either directly by exposure to dangers and hazardous substances or indirectly through local and global environmental deterioration. The highest level of a worker’s overall physical, mental, and social wellbeing is referred to as their occupational health. It is the area of medicine that deals with all occupational health and safety issues. It places a lot of at-tention on preventing dangers at the ground level. Preventive medicine is essentially what occupational health is. Similar to occupation-al health risks, environmental risks might be biological, chemical, physical, biomechanical, or psychosocial in origin. Traditional environmental health risks such as inadequate housing and sanitation are also present, in addition to agricultural and industrial contamination of the air, water, food, and land. These risks have had a variety of negative effects on health, from severe direct effects to long-lasting effects to mild, indirect, and even disputed effects. The health issues brought on by environmental and occupational risks are particularly severe in developing nations, where effective measures of hazard control are not yet widely adopted.

3.1.4 Types of environmental diseases

The distribution of infectious diseases is influenced by intricate socioeconomic and demographic factors. These include factors such as the size and behaviour of the human population, the kind and location of dwellings, the availability and implementation of vector control programmes, access to health care, and general environmental hygiene. The re-cent revival has primarily been caused by social and demographic causes such population increase, urbanisation, immigration, changes in land use and agricultural methods, deforestation, international travel, and the collapse of public health systems. The Intergovernmental Panel on Climate Change warned that climate change may raise the burden of diarrheal diseases and contribute to the expansion of risk areas for infectious diseases like dengue, putting more people at risk. In addition to allergies and asthma, neurotoxic effects of environmental contaminants, environmental influences on the onset of puberty, food, and fertility, as well as cancer, heart disease, and obesity associated with risk factors correlated to environment, diet, and genetic factors, there are a number of diseases that warrant concern. Asthma and allergic reactions, two conditions that are becoming more and more common, especially in youngsters, are influenced by outdoor air pollution. Since individuals breathe both indoor and outdoor air, it is necessary to take an integrated approach to reducing both interior and outdoor air pollution.

The phenomena of global climate change is now thought to be closely related to human activity. We can now comprehend long-term changes in climate better thanks to advances in meteorology. A prediction of the location and timing of infectious disease outbreaks might be made with the help of such knowledge. Disease hazards brought on by flooding are reduced in industrialised nations by flood control measures, sanitary infrastructure, and monitoring programmes to identify and man-age epidemics. Increases in diarrheal illness, cholera, dysentery, and typhoid are particularly worrisome in emerging nations.

3.1.5 Occupational diseases

Occupational disease is any illness associated with a particular occupation or industry. Such diseases result from a variety of biological, chemical, physical and psychological factors that are present in the work environment or are otherwise encountered in the course of employment. The major occupational diseases/morbidity of concern in India are silicosis, musculoskeletal injuries, coal workers’ pneumoconiosis, chronic obstructive lung diseases, asbestosis, byssinosis, pesticide poisoning and noise induced hearing loss. Growing population is the major concern of the government and is considered as the principal obstacle to the economic growth of the country. Emerging occupational health problems are to be tackled along with the existing tradition-al public health problems like communicable diseases, malnutrition, poor environmental sanitation and inadequate medical care.

3.1.5.1 Asbestosis

Asbestosis is a chronic lung condition caused by prolonged exposure to high concentrations of asbestos fibres in the air which comes from old and brittle asbestos products that re-lease tiny, even microscopic, fibres. Though asbestosis is believed to be mostly an occupational disease, there are reports of second hand exposure to asbestos containing dust. Asbestos is present in the environment naturally, primarily in underground rock. In most areas asbestos fibres are not released into the air because the rock is too deep to be disturbed easily. When asbestos fibres are inhaled, they can cause inflammation and scarring of lung tissues. Prolonged exposure to these fibres may cause the condition asbestosis, one of over 200 types of pulmonary fibrosis which is also classified as an interstitial lung disease.

3.1.5.2 Silicosis

Silicosis is a form of occupational lung dis-ease caused by inhaling large amounts of crystalline silica dust, usually over many years. Those who work in glass manufacturing, tunnel work and stone cutting are more likely to develop silicosis. Silica is a substance naturally found in certain types of stone, rock, sand and clay. Working with these materials can create a very fine dust that can be easily inhaled. Symptoms of silicosis usually appear after many years of exposure.

In early stages, symptoms are mild and include cough, sputum and progressive shortness of breath. As the scarring continues to worsen, the first real signs of a problem may be an abnormal chest X-ray and a slowly developing cough. It is possible to get silicosis from one exposure to a massive concentration of crystalline silica dust without a respirator. This condition is the rarest form of the disease and is called acute silicosis. Another form of the disease is called accelerated silicosis which is an aggressive and incurable form of lung disease that traditionally affects construction workers, farmers, miners and engineers. It is caused by breathing in unsafe levels of silica dust, which can scar lungs and cause them to stiffen. Although silicosis has been recognized for many centuries, its prevalence increased markedly with the introduction of mechanized mining.

3.1.5.3 Fluorosis

Fluorosis is a crippling disease resulting from deposition of fluorides in the hard and soft tissues of body. It is a public health problem caused by excess intake of fluoride through drinking water/food products/industrial pollutants over a long period. Ingestion of excess fluoride, most commonly in drinking-water, can cause fluorosis which affects the teeth and bones. Moderate amounts lead to dental effects, but long-term ingestion of large amounts can lead to potentially severe skeletal problems. Paradoxically, low levels of fluoride intake help to prevent dental caries. The control of drinking-water quality is therefore critical in preventing fluorosis. Symptoms of fluorosis range from tiny white specks or streaks that may be unnoticeable to dark brown stains and rough, pitted enamel that is difficult to clean. Chronic high-level exposure to fluoride can lead to skeletal fluorosis. In skeletal fluorosis, fluoride accumulates in the bone progressively over many years. The early symptoms of skeletal fluorosis include stiffness and pain in the joints. In severe cases, the bone structure may change and ligaments may calcify, with resulting impairment of muscles and pain. Acute high-level exposure to fluoride causes immediate effects of abdominal pain, excessive saliva, nausea and vomiting. Seizures and muscle spasms may also occur.

3.1.5.4 Asthma

Asthma is a condition in which airways narrow and swell and may produce extra mucus. This can make breathing difficult and trigger coughing, a whistling sound (wheezing) when you breathe out, and shortness of breath. Urbanization is associated with increased asthma prevalence, probably due to multiple lifestyle factors. Exposure to a range of environmental allergens and irritants are also thought to increase the risk of asthma, including indoor and outdoor air pollution, house dust mites, moulds, and occupational exposure to chemicals, fumes, or dust. Environmental factors which cause asthma are those that induce airway inflammation with eosinophils (more common) or neutrophils along with airway hyper responsiveness (AHR). Environmental tobacco smoke and mould growth are the in-door factors most consistently associated with respiratory morbidity, but their roles in initiating allergic asthma remain uncertain.

3.1.5.6 Allergies

Environmental changes are thought to be the main factor in the rapid increase and worsening of allergic diseases. In fact, various environmental pollutants such as air pollutants and chemical substances, have been shown to worsen various allergies in experimental studies. The most extensively studied environ-mental factors influencing allergy are airborne allergens: dust mites, pollens, fungi and animal dander. With the increase in urbanization and industrialization, air pollution has been on a rise. Correlatively, cases of air pollution allergy have also shot up. Air pollution alone causes allergic rhinitis in 40% of the world population. To eliminate and control allergic diseases, medical measures are necessary, but it is also essential to tackle this issue by ameliorating environmental changes.

Recap

Objective type questions

Answer to Objective type questions

Self Assessment Questions

Assignment

Suggested Reading

Reference