Environmentally sustainable development

Our society depends on the maintenance and protection of the environment. Ecological communities provide exergy (high quality energy), materials and information required for the human societies to sustain themselves. Urban development, agriculture, mineral/oil extraction, fisheries, and forestry practices can threaten the very existence of ecosystems and alter/eliminate important habitats, key species and people’s way of life.

Sustainability is the capacity to endure. Sustainability is a state of balance between resource use and the regenerative capacity of the earth. Sustainability lies in the interplay of environmental quality, economic vitality and social equity.

Environmental sustainability

Environmental sustainability refers to the maintenance of natural capital (e.g., natural resources). The term ‘natural capitalism’ was coined by Paul Hawken in 1994. Natural capital is equivalent to ecological wealth which refers to the resources and services provided by nature.  In other words natural capital is comprised of environmental resources and ecological services that can be used for life and factors of production. The human economy depends on the planet’s natural capital and the utilization of natural capital beyond its regenerative capacity results in depletion of the capital stock. The factors depleting natural capital include over-population, poverty, unsustainable resource use, environmentally degrading economic policies, and technological inputs.

The natural capital performs 3 distinct types of environmental functions:

1. Provision of resources for production - the raw materials that become food, fuels, metals, minerals, timber etc.
2.  Absorption of waste from production – both from the production process and from the disposal of consumer goods.
3. Basic ecological services – e.g., climate control, shielding of UV radiation by ozone layer, air/ water purification, water storage, nutrient/mineral cycling, soil renewal, waste treatment etc.

Concept of critical natural capital (CNC) – the concept originates from the idea that there is a certain minimal amount of natural capital necessary for ecosystems (ecosystem limits) to continue to function and provide services for its inhabitants. It is an ecosystem’s ability to support an adequate standard of living for human beings which includes drinking water, food, shelter, a moderate climate and resources for production.

It indicates human demand on the biological capacity of the earth.

Ecological sustainability

Ecological sustainability can be described as ‘securing quality of life within the limits of nature. Ecological sustainability is a conservation concept-meeting human need without compromising the health of ecosystems.

 It is the capacity of natural ecosystems to maintain their essential functions and processes and retain their biodiversity in full measure over a long period of time. Achieving ecological sustainability is a balancing act between current needs and future needs.

Sustainable development

Equity, security and the environment are the key  elements of the definition of sustainable development.Sustainable development can best be visualized in ‘the critical triangle of development’ with 3Es: environmental (ecological development), equity (social development) and economic development. Economic development has to do with the creation of material wealth (goods and services) to meet the human basic needs. Ecological development means protection and conservation of our natural resources. Sustainable should also guarantee inter and intra generation equality with respect to meeting all basic needs. In general sustainable economic development improves the economy without undermining the society and the environment.
  In 1983, the United Nations called for a high level commission, the World Commission on Environment and Development (WCED), commonly known as the Brundtland Commission. In 1987, its final report ‘our common future’ stressed the need for economic growth and development strategies in all countries that recognized the limits of the ecosystem’s ability to regenerate itself and absorb waste products.

Definitions of sustainable development

·       The sustainable development is defined as ‘forms of progress that meets the needs of the present without compromising the ability of future generations to meet their needs (our common future, 1987: The world commission on environment and development).

·       The sustainable development is defined as the maintenance of essential ecological processes and life support systems, the preservation of genetic diversity and the sustainable utilization of species and ecosystems (IUCN/WWF/UNESCO,1991).

·       The sustainable development is the improvement in the quality of human life within the carrying capacity of supporting ecosystems.

Concepts related to  sustainable development 

1.    Introduces the idea of a strong link between economic growth and natural resources/environment.

2.    Introduces the idea of a complex relationship between growth and the environment, drawing attention to the need of environmental sustainability, economic sustainability, social sustainability and the need for conciliation in conflicts between these different dimensions.

3.    Asserts that ‘zero’ economic growth can be as harmful to the environment as uncontrolled economic growth.

4.    Introduces the idea that the fight against poverty, for social justice and quality of life are essential aims in order to ensure sustainability in environmental, economic and social terms and

5.    Asserts the idea that sustainability is not a linear process and cannot be gauged against a single and developmental model.

Green economy

Green economy is an economic development model based on sustainable development and knowledge of ecological economics. This concept is often associated with ideas such as “low-carbon growth or green growth.” In green economy, the environment is an “enabler” of economic growth and human well being. Green economy includes green energy generation based on renewable energy as an alternative to fossil fuels and energy conservation for efficient energy use. Karl Burkart defines a green economy as based on 6 main aspects: Renewable energy, Green buildings, Sustainable transport, water management, Waste management and Land management. The Rio Declaration recognizes the “integral and independent nature of the Earth, our Home” and in principles 1 and 3 that humans are “entitled to a healthy and productive life in harmony with nature” and the development must “equitably meet developmental and environmental needs of present and future generations.”

Environmental distress syndrome

When the natural environment is subject to multiple stresses, it can exhibit distress symptoms.  The term ‘environmental distress syndrome’ refers to deteriorating environmental conditions and concomitant threats to human health.  In other words environmental distress syndrome is a condition that affected the human beings of the earth after years of pollution and exploitation of the planet. A distress syndrome refers to the irreversible processes of system breakdown leading to the termination of the system before its normal lifespan. An ecological system should be healthy and free from ‘distress syndrome’. Healthy ecological systems are an essential condition of healthy people, healthy communities and sustainable livelihoods.

Pollution, the introduction of contaminants into an environment that causes instability, disorder, harm or discomfort to the physical ecosystem or living organisms.

Paul Epstein (1997) of Harvard University’s centre for health and global environment lists 5 symptoms of environmental distress syndrome.

1.    The re-emergence of infectious diseases e.g., cholera, typhoid, dengue fever, drug-resistant tuberculosis.

2.    Loss of biodiversity e.g., decline of frogs in 140 countries from 6 continents.

3.    The growing dominance of generalist species –e.g., crows, Canada geese.

4.    The decline in pollinators e.g., bees, birds, bats, butterflies, beetles.

5.    The proliferation of harmful algal blooms e.g., paralytic shellfish poisoning.

Stress from human activity is a major factor in transforming healthy ecological systems to sick systems. The complex interaction of population, technology and human behaviour has resulted in anthropogenic stress on most of the world’s ecological systems (population-pollution syndrome).

Environmental stress

Environmental stress can be either natural or anthropogenic (i.e., resulting from human actions). Many natural environmental stresses such as hurricanes, droughts, floods, earthquakes and forest fires are a periodic feature of earth. But anthropogenic environmental stress includes the production and release of chemical compounds and large scale land-use changes result directly from human actions. The population explosion, agricultural expansion and industrial revolution greatly enhanced the anthropogenic stress on the environment. The intensities of ecological stresses vary in space and time. When the ecosystem is subjected to a chronic stress exceeding its tolerance limit, the ecosystem may display a syndrome of disruptions of its structure and function. The structural changes include biotic impoverishment with a reduction in size, number and abundance of organisms. The functional changes include gross community metabolism, efficiency of mineral cycles and changes in the energy flow rates.The stress in aquatic ecosystems is best exemplified by eutrophication (forced nutrient  enrichment), Increased primary production with algal blooms and insufficient decomposition of organic matter with increased anaerobic zones. There is a replacement of longer lived larger species by short – lived opportunistic species.

Progression of global environmental stress

All environmental changes progress at two levels:

Systemic global changes refer to changes operating at the global scale. For example, the doubling of carbon dioxide from more fossil fuels leads to enhanced greenhouse effect which leads to global climatic changes.

Cumulative global changes refer to the snowballing effect of local changes which add up to produce change on a global scale. E.g., acid rain or soil erosion.

An ecological system is healthy and free from ‘distress syndrome’ if it is stable and sustainable that is if it is active and maintains its organization and autonomy over time and is resilient to stress (Costanza, 1992).

Costanza’s concept (1992) of ecosystem health indicators

Costanza proposed 6 attributes of ecosystem health indicators.

1.    Homeostasis (self – regulation) 2. Absence of disease 3. Diversity or complexity (number and types of species) 4.stability or resilience 5. Vigour or scope for system growth and 6. Balance between system components.

Xu and Mage (2001) proposed 4 sets of criteria to assess ecosystem health: structural changes, functional changes, organizational changes and dynamics.

"The earth is what we all have in common."- Wendell Berry.
"In nature nothing exists alone." -Rachel Carson, Silent spring.

Environmental Education - objectives and importance

Environmental problems have become the issues of global concern due to their worldwide impact. A better understanding of one’s own environment is indispensable for its rational development. Environmental education (EE) is a powerful means to know and understand the physical and cultural environment as a whole with the rational use and conservation of environmental resources for development.

Definition

The international union for the conservation of nature (IUCN) has stated that ‘environmental education is the process of recognizing values and clarifying concepts in order to develop skills and attitudes necessary to understand and appreciate the interrelatedness among men, his culture and his biophysical surroundings’.

Environmental education is the cornerstone of long-term environmental strategies for preventing environmental problems, solving those which arise or have occurred and assuring environmentally sound sustainable development.

Aims of environmental education (UNESCO, Tbilisi declaration, 1978)

1.    To foster awareness and concern about environmental issues that affect us at local, regional, national and global levels.

2.    To provide every person with opportunities to acquire the knowledge, values, attitudes, commitment and skills needed to protect and improve the environment.

3.    To develop and reinforce new patterns of environmentally sensitive behaviour among individuals, groups and society as a whole for a sustainable environment.

5 – Objectives of Environmental education (UNESCO – UNEP Jan.1996)

1.    Awareness – to acquire an awareness and sensitivity towards the environment as a whole and the issues, questions, and problems related to environment and development.

2.    Knowledge – to acquire a basic understanding of the environment and its associated problems.

3.    Attitudes – to acquire social values, strong feelings of concern for the environment and the motivation to actively participate in protection of the environment.

4.    Skills – to acquire the skills for identifying and solving environmental problems.

5.    Participation – to develop a sense of responsibility and motivation to be actively involved at all levels in creating a sustainable environment.

Guiding principles of environmental education

(UNESCO-UNEP-IEEP-the Belgrade Charter, 1975)

·       Environmental education should be a continuous life-long process both in-school and out-of-school, both formal and non-formal.

·       Environmental education should be interdisciplinary in its approach.

·       Environmental education should emphasize active participation in preventing and solving pollution and environmental problems.

·       Environmental education should examine major environmental issues from a holistic point of view.

Global initiates on Environmental education

The UNESCO and UNEP created 3 major declarations that have guided the course of environmental education (EE).
Stockholm Declaration (Sweden, June 5-16, 1972)
It declared that EE must be used as a tool to address global environmental problems. The document published has 7 proclamations and 26 guiding principles regarding the preservation and enhancement of human environment.
The Belgrade Charter (Belgrade, October 13-22, 1975)
The charter added goals, objectives and guiding principles for new environmental programmes. It also added the general public in the programmes.
The Tbilisi declaration (Georgia/USSR, October 14-26 1977)
This declaration updated the goals, objectives, characteristics and guiding principles of environmental education.

Environmental teaching

Awareness and education are important inputs for a correct appraisal of environmental problems. Environmental education can be taught at various levels: formal and non-formal systems including adult education. In the formal level, there are 4 distinctive but chronological steps, which are mutually supportive.

Primary level-àlower secondary level--à higher secondary level--à tertiary level

At the primary level emphasis has to be on environmental awareness. At the lower secondary level, learners have to be taught to appreciate the real-life environmental situations at the local level. At the higher secondary level, Environmental conservation has to be emphasized. At tertiary level, learners have to be taught on sustainable development i.e., sustainable agriculture and forestry, integrated land use management, eco-farming and waste management etc.

Approaches of EE in formal education

1.    Infusion approach – the concepts and values of EE are infused with other subjects that are already included in the curriculum such as physics, chemistry, geography and languages. This approach is adopted at the school level in India.

2.    EE as separate subjects – Indian universities have introduced separate subject at undergraduate and post graduate levels.

3.    Occasional programmes for EE- Under this approach, occasional camps or eco-excursions are organized solely for the purpose of environmental education.

Conclusion

Education has always played a crucial role in the society because it inculcated necessary skills and attitudes in the learner’s life. So education has been identified as a critical driving force in environmental education. The content and approaches of environmental education need sufficient review and change at the various levels of formal, non-formal and informal education at all levels of society.

Environmental diseases

The environment is intimately associated with human health, illness and mortality. Environmental exposures to potentially hazardous agents such as microbes, toxic chemicals and metals, pesticides and ionizing radiations account for many of the diseases of humans, animals and plants. The concept of ‘environmental disease’ is usually applied to illnesses from chemical exposure due to environmental pollution. In other words illnesses and conditions caused by factors in the environment are collectively called environmental diseases. Pesticides, chemicals, radiation, air pollution and water pollution are some of the man-made hazards that are believed to contribute to human illnesses. Human beings made the global commons air, water and land into the global dustbins of human wastes.

Exposures to environmental pollution remain a major source of health risk throughout the world. Globally an estimated 24 percent of the disease burden (loss of healthy life years) and an estimated 23 percent of all deaths (premature mortality) was attributed to environmental factors. Among the children 0-14 years of age, the proportion of deaths attributed to the environment was as high as 36%. Of the 102 major diseases covered by the World Heath Report in 2004, environmental risk factors contributed to disease burden in 85 categories. Poor air quality contributes to cancers, cardiovascular diseases, asthma and other illnesses. Poor water quality can lead to gastrointestinal illness, neurological problems and cancer. Pollution is one of the biggest global killers, affecting over 100 million people.

Globally the two groups of people that are most affected by environmental diseases are the rural poor and the urban poor who live in slums.  About 25-50% of the world’s urban population live in extreme poverty. They lack basic necessesities for a decent life such as adequate housing, drinking water, sanitation or garbage collection. About 75% of the rural households in India burning wood, dung cakes and crop residues for cooking. Epidemiological studies in developing countries have linked exposure to indoor air pollution from biofuels with four major categories of illnesses: acute respiratory infections (ARI) in children; chronic obstructive lung diseases such as asthma and chronic bronchitis; lung cancer and still-births and other problems at birth. Rural coal smoke exposures seem to increase lung cancer risks by a factor of nine or more. Lung cancer in China is attributed to high levels of coal smoke. 

One recent study in Colombia found women exposed to smoke during cooking were more than three times more likely suffer from chronic lung disease. In developed countries, energy efficiency improvements make houses relatively airtight, reducing ventilation and raising indoor pollution levels. Increasing numbers of urban homes and buildings are now ‘air tight’ which can lock in bio-allergens (dust mites, moulds, cockroaches, insect droppings or animal dander) and also irritants (dust, odours from oil paints, room fresheners) and other pollutants. These urban environmental conditions may lead to ‘sick – building syndrome’ (SBS). A number lifestyle changes in living conditions in the indoor environment such as carpeting, upholstered furniture, mattresses, humidifiers and air conditioning make it easier for dust mites and moulds to thrive.

An estimated 500,000 women and children die in India each year due to indoor air pollution (IAP) – related causes, which is 25% of the estimated IAP-related deaths worldwide (World Bank Report). A report of WHO in 2002 showed that 36% of lower respiratory infections were attributable to solid fuel use alone and 1% of all respiratory infections to outdoor pollution.

Causes of environmental diseases

Industrial growth, urbanization and the increasing use of synthetic organic substances have serious and adverse impact on the environment. Population growth indirectly driving climate changes by contributing to deforestation, overgrazing, soil erosion and desertification. Overuse of land may lead to a drop in food production, depletion of natural resources and a rise in pollution.  Chemical fertilization, chemical control of insect pests and weeds, mechanization and irrigation all have an impact on the land environment. The land vegetation and organic matter had been reduced about one-third. ‘Formerly man had been part of nature’ said Lynn White Jr. and ‘now he was the exploiter of nature’. Man dominates all other living creatures and exploits all available natural resources. He has been working as an agent of all environmental degradation and now he becomes its prime victim.

Types of environmental diseases

1.    Vector – borne diseases – transmitted through insects e.g., malaria, dengue fever, encephalitis, schistosomiasis.

2.    Vessel – borne diseases – transmitted through some kind of vessel e.g., a cup, water, food, milk, blood etc. e.g., diarrhoea, dysentery, cholera.

3.    Air – borne diseases – transmitted through air medium e.g., flu, tuberculosis, measles, heart and lung diseases and cancer.

Malaria is strongly connected to environmental factors such as climate, rainfall, irrigation and sanitation. Malaria is caused by the blood parasite plasmodium. This parasite is transmitted by the bite of an infected female anopheles mosquito. An estimated 42% of the global malaria burden could be prevented by environmental management.

World Health organization (2002) estimated that 88% of all causes of diarrhoea globally were attributed to water pollution, sanitation and hygiene. About 18% of the world’s population still lacks access to safe drinking water and nearly 40% have no access to proper sanitation.

Examples of environmental diseases

Air pollutants have both acute and chronic effects on human health. Urban air pollutants can cause or exacerbate cardiovascular disease, cancer, allergies, asthma and lung disease. Benzene, nitrogen dioxide and small particulate matter can cause damage to the bone marrow and the immune system.  Air pollution is shown to be the cause for 1 in 10 deaths due to lung cancer. Air borne particulates increase the severity of asthma attacks, lung disease and chronic obstructive pulmonary disease (COPD). Exposure of humans to air pollutants may be a cause for acute respiratory distress syndrome (ARDS), sick building syndrome (SBS), multiple chemical sensitivities (MCS), and chronic fatigue syndrome (CFS).

Water – and food – borne diseases that result in diarrhoea or dysentery are the leading cause of environment – related health problems in the world. The primary diarrheal diseases include amoebiasis, cholera, giardiasis, and other protozoal diseases; samonellosis, shigellosis, typhoid and paratyphoid fevers and viral diseases. These diseases collectively cause more than 16% of the global environmental disease burden (58 million DALYs per year) and 13% of deaths (1.7 million per year).

Human health effects of heavy metals in soil include brain and nervous system damage, kidney damage, liver toxicity and birth defects.

Ultraviolet and other ionizing radiations are very damaging to cell components and DNA and they trigger development of cancerous tumours.

Quotes for reflection

“Pollution of the environment  is the root cause of all human health problems”.

"Environmental pollution is an incurable disease. It can only be prevented."
                                                                                 -Barry Commoner.

Environmental Carcinogenesis

Environmental carcinogens include outdoor and indoor air pollutants as well as soil and drinking water contaminants. Epidemiological studies have shown that 70-90% of all cancers are environmental.  Environmental factors such as lifestyle, personal habits, diet, chemicals and radiation and infectious diseases account for about three quarters of all cancers. The China admits that there has been an 80% rise in the mortality rate from cancers over the past 30 years. The United States has one of the world’s highest incidences of cancer associated with environmental pollution. The most recent data suggests there were 223,000 deaths from lung cancer caused by air pollution around the world (International Agency for Research on Cancer, IARC).The IARC classified ambient air pollution as cancer causing agent (carcinogen). Studies also show that nearly 30% of the total mortality in several industrialized countries is due to cancer.

Cancer

A tumour or cancer is an abnormal mass of tissue whose cells undergo rapid and uncontrolled growth at the cost of remaining cells. The tumours are classified as benign or malignant. Benign tumours remain localized in a specific area at the site of origin, forming a single mass enclosed in a capsule. They slow growing and can be removed effectively with surgery. Malignant tumours are cancerous with rapidly growing and actively moving cells.  The cancer cells migrate through the blood and lodge at distant sites which are called metastasis. Cancers or malignant tumours are uncapsulated and invasive.

Carcinogens

Carcinogens are agents that induce cancer. Primary or direct – acting carcinogens are those that do not require metabolic activation e.g., mustard gas. Some carcinogenic chemicals are inactive and require metabolic activation. They are secondary carcinogens e.g., carbon tetrachloride. The parent compound is called a procarcinogen  and is converted to a reactive metabolite called proximate carcinogen and then to a highly reactive species termed as ultimate carcinogen, which are covalently bind to macromolecules like DNA. Co-carcinogens (promoters) are substances that potentiate or promote the effects of carcinogens e.g., cyclopropenoid fatty acids. Carcinogenic agents can further classified as genotoxic or non-genotoxic, based on the ability to alter the genetic systems in cells. Asbestos increase the incidence of cancer, but do not possess genotoxic effects.

 3- stage model of chemical carcinogenesis

 The chemical carcinogenesis comprises 3- sequential and successive steps: initiation, promotion and progression. Tumour initiators can be defined as carcinogens capable to induce a first driver mutation in a dividing cell so that an initial clone of mutated cells emerge. Tumour promoters can be defined as non-genotoxic carcinogens capable of causing clonal expansion of initiated cells i.e., able to induce proliferation of mutated cells. Tumour progressors are carcinogens that advance mutated cells from promotion to progression  and transform a mass of fully malignant cells. So carcinogenesis is a multiple step process.

 Cancer develops over a peroid of several years (latent period) and has many causes. There are more than 100 types of cancers. Scientists have identified more than 300 altered genes called oncogenes that can signal the cell to divide out of control. One of the characteristics of chemical or physical carcinogenesis is the usually long latent periods (years to several decades) between the contact with the carcinogen and appearance of a tumour. The degree of cancer risk from pollutants depends on the concentration, intensity and duration of exposure. E.g., saccharin is carcinogenic only at higher doses.

Environmental carcinogens

Arsenic, asbestos and radon are three prominent human carcinogens strongly associated with lung cancer.  Benzene is known to cause leukemia (blood cancer) in human beings. Benzene has widespread use as solvent in the chemical and drug industries and a gasoline component. Drinking water that is contaminated with a high level of arsenic over a long period of time is known to increase the risk of lung, bladder and certain types of skin cancers. Exposure to arsenic caused 3,700 lung, bladder and skin cancer deaths in Bangladesh alone. An increased risk of stomach cancer has been reported in areas with high nitrate levels in drinking water. There are more than 75,000 chemical compounds in contaminated waters come from industry, agriculture and consumers/homes. Bisphenol A (BPA), a building block of polycarbonate plastic is an endocrine disruptor linked to breast and prostate cancer. Exposure to vinyl chloride (PVC) is linked to the development of liver and brain cancer. Polycyclic aromatic hydrocarbons (PAHs), a product of incomplete combustion of organic compounds is possibly carcinogenic. The chemical compounds with carcinogenic potential include benzopyrene, benzene, organic solvents, pesticides, dioxins, several heavy metals (arsenic, cadmium, lead, mercury) and others.

Cancer is a preventable disease

According to the National Cancer Institute, 80% of the cancers are due to factors that have been identified and can potentially be prevented. About 20 years ago, 1 out of 10 people were diagnosed with cancers and other debilitating diseases.  Now we are faced with 1 out of 2 people being diagnosed with cancer. The environment, which sustains the life of all living organisms, can also be a significant contributor of ill health. The natural environment is crucially a ‘commons’ a public good. Respect the ecosystems and keep them healthy.

Environmental hormones

Daily use of chemicals is an essential habit of modern society. Large scale production and repeated use of synthetic chemicals introduce many toxic and persistent chemical residues into the environment. As a result, humans and wildlife are constantly exposed to the chemical residues through air, food and water. Some of these chemicals in the environment interfere with, block or mimic the effects of natural hormones. Such environmental contaminants which modulate the activities of natural hormones are called environmental hormones, endocrine disrupting chemicals (EDCs), or environmental estrogens (EE) or xenoestrogens. It has been scientifically shown that environmental hormones may elicit a variety of adverse health effects in both humans and wildlife including promotion of hormone- dependent cancers, reproductive organ disorders and reduction in reproductive fitness.

Kinds of hormone mimicking chemicals

The term ‘environmental estrogen’ is currently used to denote both plant – derived estrogens (phytoestrogens) and the anthropogenic (synthetic) estrogens (xenoestrogens). The naturally occurring estrogens in either humans or animals are called endogenous estrogens and all compounds with estrogenic properties entering the body from an outside source as exogenous estrogens.

Phyto-xenoestrogens

Phytoestrogens (phyto meaning plant) are naturally occurring estrogenic compounds that are found in a variety of plant foods such as beans, seeds and grains. These compounds are generally weak estrogens when compared to xenoestrogens. Many phytoestrogens belong to the large group of plant phenolics. Caffeic acid is one of the most common plant phenolics found in chicory coffee, artichoke, olive oil and red wine. The other major phytoestrogens consumed in excess quantities by humans are  isoflavonoids and lignans. Strong phytoestrogens are present in soy, red clover, caffeine and Chester berry.

Synthetic xenoestrogens

The word xenoestrogens is derived from the Greek words xeno, meaning foreign, estrus, meaning sexual desire and gene, meaning to generate and literally means ‘foreign estrogen’. The synthetic xenoestrogens include both chlorinated and non-chlorinated compounds. The synthetic xenoestrogens are found in plastics (BPA), pasticizers (phthalates), industrial chemicals (polychlorinated biphenyls,PCBs; dioxins), pesticides(DDT, methoxychlor),fungicides(vinclozolin), pharmaceuticals(diethylstilbestrol) and heavy metals(arsenic, lead, chromium, cadmium).

Mode of action

Environmental estrogens have been shown to directly bind to the estrogen receptor(ER) and function as either agonists or antagonists. The estrogen agonists are compounds that mimic the effects of natural estrogen. But estrogen antagonists block the action of estrogens by interfering with the normal functions of the estrogen receptor. In general environmental estrogens have the ability to mimic/ antagonize the effects of natural hormones. They also modify hormone receptor levels and the pattern of synthesis and metabolism of natural hormones.

Sources of synthetic xenoestrogens

Plastic additives- phthalates and bisphenol A(BPA) are plastic additives. Phthalates are used extensively in industry, plastic packaging, inks, paints, and vinyl products. Bisphenol A is used in the production of epoxy resins and polycarbonate plastics. They are lipophilic and accumulate in the fat. They cause human breast cancers.

Brominated flame retardants(BFRs) – are a group of industrial chemicals mainly used in electric devices, textiles and cars. They are highly lipophilic and bioaccumulate in adipose tissues. They have been reported to disrupt thyroid, androgen and estrogen signalling.

Perfluorinated chemicals(PFCs) – are used to make non-stick cookware. They are completely resistant to biodegradation. PFOA decreases sperm quality and causes kidney disease or thyroid disease.

Organotins,TBT (tributlytin) is an active ingredient in antifouling paints. Exposure to TBT causes obesity and metabolic disorders.

Dioxins – are the most deadly organochlorine chemicals found in pesticides, plastics, solvents, detergents, and cosmetics.  More than 90% of human exposure is through food, mainly meat and dairy products, fish and shellfish. They are highly toxic and bio- accumulate through food chain.

Human health effects

Synthetic xenoestrogens may act as false messengers and disrupt the process of reproduction.  Xenoestrogens induce precocious puberty in girls with premature secondary sexual characters.

They may be associated with the development of learning disorders, severe attention deficit disorders and developmental defects.

TBT may act as androgens and fungicide vinclozolin act as anti-androgens.

In males, exposure to xenoestrogens decreases sperm quality and counts, incidence of testicular cancers and crytorchidism (undescended testis). In females exposure causes endometriosis and endometrial cancer.

Exposure to dioxins can cause reproductive and developmental problems, damage the immune system, interfere with hormones and also cause cancers.

Environmental xenobiotics

A xenobiotic is a compound which is foreign to a particular organism. The term ‘xenobiotic’ is a combination of the Greek words ‘xenos’ meaning strange or foreign and ‘bios’ meaning life. They are mostly synthetic substances used as agrochemicals, pharmaceuticals, petrochemicals, colorants, adhesives, preservatives and certain chemicals in plastics.

 Kinds

The xenobiotics may be naturally occurring as well as man-made (anthropogenic). The man-made chemicals are synthetic substances like pesticides, organic solvents, medicaments, ethanol etc. The naturally occurring chemicals are produced by plants , microorganisms or animals as ‘chemical warfare agents’. E.g. pyrethrins, nicotine, mycotoxins, tetrodotoxin (newt) and antibiotics.

    Xenobiotics can be exogenous to living organisms, which include drugs, food additives, pollutants, insecticides, chemical carcinogens etc. They are not normally ingested or utilized by the organisms.

Endogenous xenobiotics are not foreign substances but are synthesized in the body or produced as metabolites of various processes in the body e.g. bilirubin, bile acids, steroids, eicosanoids and certain fatty acids.

Sources

 The major sources of xenobiotic compounds are from the chemical and pharmaceutical industries, mining operations, fossil fuels and intensive agriculture.  Food additives are xenobiotics which have no nutritional value, are of no use in the body and can be harmful, if consumed in excessive amounts. Human beings are increasingly exposed to the kinds and amounts of xenobiotic agents from industrial, agricultural, pharmacological and lifestyle applications.

Sites of action

 The xenobiotic agents target the active sites of enzymes, DNA (genetic material) and lipid membranes.

Mechanism of toxicity

The exposure to xenobiotic agents disrupts normal cell functions. They easily bind and damage structural and dynamic proteins e.g. enzymes. They also bind and damage DNA and induce mutations (nucleophilic).  They bind and damage lipid membranes (lipophilic).

They react in the cell with oxygen to form ‘free radicals ‘which damage lipid, protein and DNA.

Effects of xenobiotics

The metabolism of xenobiotics can result in cell injury/cell death by cytotoxicity, immunologic damage (altering its antigenicity) or cancer (disorder in cell growth).

The xenobiotics may directly bind to a cellular component and inhibit its normal function. For example carbon monoxide binds to haemoglobin in the red blood cells and prevents the haemoglobin from binding with oxygen.

Cadmium binds with a transporting blood protein metallothionein which accumulates in the kidney and damage the filtering function (tubular cells).

Metabolism of xenobiotics

The main organ involved in xenobiotic metabolism is liver. The xenobiotic transforming enzymes are present in the cytosol and endoplasmic reticulum of hepatocytes.

The biotransformation involves phase I and phase II reactions.

The main purpose of the reactions is converting the xenobiotic lipophilic (lipid-soluble) agents into hydrophilic compounds and facilitates excretion. First phase of reactions are performed by liver or gut enzymes before the compounds reaches the systemic circulation and limits its bioavailability. Several enzyme systems participate in phase one metabolism of xenobiotics. The cytochrome P450s (CYPs:450s) detoxify and / or bioactivate a vast number of xenobiotic chemicals. Phase I involves the addition of reactive functional groups by oxidation, reduction or hydrolysis.  Phase I reactions convert xenobiotics into more reactive metabolites (metabolic activation). Phase II biotransformation is catalysed often by the ‘transferase’ enzymes that perform conjugating reactions. Phase II reactions include glucuronidation, sulfation, methylation, acetylation, glutathione conjugation and amino acid conjugation.  Phase II reactions cause the xenobiotic metabolites into more hydrophilic and readily excretable compounds.

‘Poisons are xenobiotics, but not all xenobiotics are poisonous’

Pollution of global marine environment

The oceans are enormous in their size, volume and depth. All oceans and seas are continuous. They are complex, extensive and stable ecosystems, controlled by a variety of physical, chemical and biological processes. They form a largest ecological system. The life on earth first originated in the seas and oceans. The marine environment dominates that of land (70% of the earth’s surface.) The ocean is the giant reservoir of water – water wealth 97.3 % in oceans and 2.7 % on the land. They are complex chemical system – 96.6% of seawater is pure water and only 3.4% contain dissolved solids. Ocean currents distribute heat energy around the globe and moderate earth’s surface temperature. They are the rich reservoir of carbon dioxide (130 trillion tons: 50 times more than air) and mineral wealth (50 million billion tons). The oceans are the richest source of the atmospheric oxygen and large reservoir of momentum and energy. Off-shore waters of marine environment have nearly 20% of world’s oil resources. They are the huge reservoir of biological wealth – 180 thousand species from small bacteria to huge mammals – 25000 varieties of fish. At present 75-80 % of the total global transports by world oceans and seas.

Role  of  Life supporting functions

The ocean absorbs a great amount of carbon dioxide and pollutants. The ocean absorbs 80 percent of the heat added to the Earth’s system by climate change. The oceans provide humans with foods, recreational opportunities, and transportation corridors. The oceans are comprised of diverse habitats that support a wealth of marine wildlife. Humans have been disposing a lot of 'waste into the ocean - trash, sewage, oil, chemicals, heat.

Role as Global carbon sink

The ocean is a natural sink of co2. The net annual uptake of co2 by oceans is estimated to be approx. 2 thousand million tones. The CO2 dissolves in sea water and forms carbonic acid. It hydrolyses into carbonates and bicarbonates. About 90 % of CO2 exists as carbonates and bicarbonates. CO2 is taken up by phytoplankton in photosynthesis and converted into plant material.

Global marine environmental changes

About 390 million tonnes of run-off water enters our marine environment each year. Approx. 7 billion tons of litter enters the world's oceans each year. Approx. 35% of mangrove area has been lost or converted. Approx. 20% of coral reefs have been destroyed globally in the last few decades. Coastal wetland loss in some places has reached 20% annually. Indiscriminate fishing practices kill and waste between 18 - 40 million metric tons of "unwanted" fish, seabirds, sea turtles, marine mammals, and other ocean life annually (FAO - U.N). Oil spills may occur when an ocean oil rig springs a leak or when an oil tanker wrecks. E.g., The Santa Barbara spill in 1969, and the Exxon Valdez spill in Alaska in 1989. In 1991, millions of gallons of oil were released into the Persian Gulf during the Gulf War.

Global and Indian coastal lines

Two-thirds of the world population lives in coastal lines. Over 90% of the world’s living biomass is contained in oceans. Coastal areas produce 80% of the marine resources.Indian coastal line measures about 7500 km and 2000 km wide Exclusive Economic Zone. The Indian coastline supports almost 30% of its human population. India is the 7th largest marine fishing nation in the world. The Bay of Bengal and the Arabian Sea are rich fishing grounds.

Marine biodiversity

Animal life in the sea is very varied and more diversified in terms shape, size, form and weight-right from microscopic plankton to the giant whale. The total number of marine species is ranging from 178,000 species to more than 10 million species.
Total number of marine species described: approx. 3 million, which represent about 15% of all described species. Coral reefs (the high number of species per unit area) have 1 - 9 million species. Deep sea (its enormous area) contains 5 million species.
Ecosystem services of Continental shelf
Continental shelves account for at least 25% of global primary productivity. It provides 90–95% of the world’s marine fish catch. It produces 80% of global carbonate and 50% of global de-nitrification. It carries out 90% of global sedimentary mineralization (UNEP 1992).Composition of Marine Biodiversity

— 
321 species of marine fungi
40000 species of foraminiferans
Of the 28000 fish species , ¾ colonizes marine habitats
More than 2500 macro fauna species
More than 600 species of Benthic algae

Marine physical diversity gradients

—  Depth gradient -dissolved gases decreases with depth. 

—   Salinity gradient-species diversity declines as the concentration of dissolved solutes deviates from normal sea water.

—  Nutrient gradient- species diversity decrease as a function of nutrients from the shore to the open sea.

—  Latitudinal gradient - species  diversity increase  from the poles to the tropics

Diversity of coastal habitats—

• Mangrove swamp ecosystem – water logged saline soil
• —Sea grass ecosystem – highly productive macro algae
• —Coastal lagoon ecosystem – most fertile littoral ecosystems
• —Coral ecosystem – richest in species
• —Estuarine ecosystem - meeting place of river and sea
• —Delta ecosystem –
• —Sandy beach ecosystem – intertidal zone
• —Rocky shore ecosystem – intertidal zone
• —Coastal upwelling ecosystem

Marine life

Marine organisms can be categorized into plankton, nekton and bentos.
Plankton is mostly microscopic size.They have no means of locomotion or self-propulsion. The surface of each plankter is large in relation to bulk and often with elongate body parts. Phytoplankton includes microscopic diatoms, dino flagellates, green algae, blue green algae whereas Zooplankton consist of many protozoans, crustaceans, small mollusks, few worms, a host of larvae copepods and macro-crustaceans.
Nekton – They are actively swimming organisms which include all evolved species of fish.
Small and big organisms including dolphins, porpoises and whales
Benthos- are bottom dwelling organisms. They are categorized into epifauna and infauna.
Those benthic organisms living on the sea floor are called epifauna and those living in the sea floor are called infauna. Sessile benthos includes sea weeds, sponges, anemones, corals, barnacles and oysters. Creeping benthos consists of crabs, lobsters, snails and echinoderms. Burrowing benthos has clams and worms.

Human impacts on marine environment

Direct effects include dredging and dumping (reclamation), removal of biota (through fishing) and construction of marinas, port facilities or breakwaters.
Indirect effects include introduction of foreign diseases or species and discharge of nutrients and toxic pollutants.
Direct human impacts:
Dredging refers to excavation of sediments from the sea bed to make the water deeper. Loss of habitat alters species composition. Dumping (or reclamation) refers to the deposition of sediments in the seas to create new land. Reclamation results in complete physical loss of the natural environment e.g.port expansions, shipping activities, or construction canals. Introducing soil and mud into the water column increases turbidity and sedimentation which alters benthic flora and fauna.
Over-fishing - Over-fishing of a target species removes predator or prey animals. Over-fishing affects the species composition and ecological food chain
Trawling - Trawling results in by-catch of non-target species, such as seals, dolphins, sharks, sea snakes, fish, turtles and invertebrates. Trawling has the potential to devastate benthic habits.
Coastal aquaculture can contribute to degradation of coastal habitat.
Land based discharge (sewage, industrial effluent and urban/river run off etc.) and atmospheric inputs from industry sources account for some 77% of marine pollution.
Maritime transport is responsible for some 12% of the total.Marine environmental problems

Coastal erosion – sand erosion by strong winds, high waves, heavy rains, flooding, and storm waves.
Pollution with toxic substances.
 Eutrophication – over-enrichment with nutrients.
Sedimentation- Land based discharge and deposition of sediments.
Over exploitation of living and non-living resources for  selective commercial exploitation.

          

Environmental pollution of particulate matter

Particulate matter (PM)

-PM is a complex mixture of air borne particles that differ in size, origin and chemical composition, all of which are <10 µm in size. e.g. dust, smoke, soot. PM is composed of liquid aerosol particles and solid aerosol particles –suspended in and move with the air. Aerosols are droplets of liquids and are  generally below 5 µm size. PM is one of the six EPA ‘criteria pollutants’. PM has no fixed composition. The particles may consist either of only one chemical (e.g. sulphate, sulphuric acid, or lead oxide ) or a number of pollutants ( organic chemicals, metals, dust ). US EPA described PM pollution as ‘mixture of mixtures’. PM is among the most harmful of all air pollutants.

Sources of particulate matter

Natural particulates originate from volcanoes, dust storms, forest and grassland fires, living vegetation and sea spray. Anthropogenic particulates originate from burning fossil fuels, incinerating wastes and smelting metals.

        Types of PM particles

Primary particles are directly emitted from sources. Secondary particles form as a result of the interaction of chemicals such as SO₂, NO_x and VOCs with other compounds in the air.

Sources of PM and PM precursors

Mobile sources – Vehicles – VOCs , NO₂, PM

Stationary sources – power plants, factories – NO₂, SO₂, PM

Area sources – dry cleaners, gas stations – VOCs.

Natural sources – forest fires, volcanoes, PM

     Characteristics of particles

PM₁₀ –They are inhalable coarse particles with a diameter range 2.5 - 10 microns.They undergo rapid sedimentation. They occur near roadways and dusty industries. They bypass the body’s natural defenses in the nose and throat and enter lungs.

PM _2.5 – are fine particles with a particle diameter 2.5 microns. They remain suspended in the air and can travel extremely long distances. They are emitted from power plants, industries, and automobiles. They penetrate deeper into the lungs and damage lung tissues.

PM  _0.1 – They are ultra-fine particles or nano-particulates, smaller than 0.1 micron in diameter. They consist primarily of inorganic ions, hydrocarbons and metals. They pass from lung tissue into blood stream and circulate like oxygen molecules.

   Suspended particulate matter (SPM)

Dust is about 100 microns in diameter and they are removed in the nasal passages e.g. coal dust, cement dust. Fumes are suspended solids of less than I micron in diameter. E.g.zinc or lead oxides

Mist consist of liquid droplets with a diameter of  less than 2.0 microns.e.g. sulfuric acid mist

Smoke consists of solid particles with a diameter range of 0.05 – 1.0 microns.  They form as a result of incomplete combustion of fossil fuels. Aerosol Liquid or solid aerosols are less than 1.0 micron in diameter.

    Deposition of particulates in human body

     Coarse particles deposit in the upper respiratory tract and large airways (nose and throat) and are cleared out.Fine particles penetrate deep into the lungs and reach terminal bronchioles and alveoli. They stay there longer periods of time. Ultra-fine particles enter the blood and circulate throughout the body.

•          PM₁₀ - Inhalable particles, deposit in the extra thoracic /upper tracheo-branchial region.

•          PM _2.5 - Fine particles,deposit in deeper lung.

•          PM  _0.1 - Ultra-fine particles,pass into the circulatory system.

Sources of particulate pollution

•       Motor vehicle emissions

•       Power generation

•       Industrial combustion

•       Metal smelting

•       Wood / biomass burning

•       Construction / demolition

•       Road dust

Determinants of PM concentration – The factors like weather patterns, wind, stability (Air Vertical movement), turbulence, precipitation, topography, height of smoke stack and temperature of gases determine the concentration of particulates in a given locality of the environment..

Particle deposition in the lungs- Particle size is the most important factor for target tissue deposition.

 People at risk (sensitive human population) to particulate pollution

1. Children under 18 age.
2. Adults 65 and older.
3. Anyone with chronic lung diseases such as asthma, chronic bronchitis or emphysema.
4. Anyone with a cardiovascular disease.
5. Anyone with diabetes.

Environmental impact

•       Impairment of visibility- fine particles in the atmosphere  reduce visibility.

•       Damage to environment – particles can be carried over long distances by wind and settle on ground or water. They make lakes and streams acidic, deplete nutrients in soil and damage sensitive forests and farm crops.

•       Aesthetic effects – settling particles on statues and monuments can stain or damage stone and other materials.

Long-term human health effects  

Chronic exposure to  atmospheric particulates in human beings cause asthma, bronchitis, chronic obstructive pulmonary disease (COPD), pneumonia, upper respiratory tract or lower respiratory tract disorders and lung cancer.