Water pollution and water borne diseases

Overview

Water is an essential and general need of life with an undeniable effect directly or indirectly. All industrial, environmental, and metabolic processes are water dependent. In living organisms, water plays a number of roles such as solvent, temperature buffer, metabolite, living environment, and lubricants. Water, however, is said to be polluted when some of the water quality parameters have been hampered by unguided and irregularities from several anthropogenic activities, thus rendering water unfit for intended use. Water pollution may pose serious threat to the environment as well as lives. Pollutant effects may vary depending on their types and source. For instance, while heavy metals, dyes, and some other organic pollutants have been identified as carcinogens, hormones, pharmaceuticals, and cosmetics and personal care product wastes are known as endocrine disruptive chemicals. These pollutants, which enter into the water body through various channel but predominantly anthropogenic, have become a great concern to environmentalists due to various hazard they pose on the environment (1).

Safe and readily available water is important for public health, whether it is used for drinking, domestic use, food production or recreational purposes. Improved water supply and sanitation, and better management of water resources, can boost countries’ economic growth and can contribute greatly to poverty reduction. In 2010, the UN General Assembly explicitly recognized the human right to water and sanitation. Everyone has the right to sufficient, continuous, safe, acceptable, physically accessible and affordable water for personal and domestic use (2).

Key facts

Over 2 billion people live in water-stressed countries, which is expected to be exacerbated in some regions as result of climate change and population growth.
Globally, at least 2 billion people use a drinking water source contaminated with faeces. Microbial contamination of drinking-water as a result of contamination with faeces poses the greatest risk to drinking-water safety.
While the most important chemical risks in drinking water arise from arsenic, fluoride or nitrate, emerging contaminants such as pharmaceuticals, pesticides, per- and polyfluoroalkyl substances (PFASs) and microplastics generate public concern.
Safe and sufficient water facilitates the practice of hygiene, which is a key measure to prevent not only diarrhoeal diseases, but acute respiratory infections and numerous neglected tropical diseases.
Microbiologically contaminated drinking water can transmit diseases such as diarrhoea, cholera, dysentery, typhoid and polio and is estimated to cause 485 000 diarrhoeal deaths each year (2).

The most common ways of polluting the water include:

Waste disposal:

directly into water streams
onto the soil from which contaminants may leak into the groundwater below

Urban and agricultural runoff;
Animal waste could also add dangerous pathogens (usually microbial groups, viruses and intestinal parasites) into the water;
From air via acid rain - water can get polluted with air contaminants (that have sometimes traveled long distances – such as the case of Hg) that reach the land and water via acid rain. During precipitation, air pollutants may get dissolved in the water drops and, as a result, they may acidify the water - which is why polluted rainwater is referred to as “acid rain” (3).

Water pollution can affect us:

Directly – through consumption or bathing in a polluted stream (such as consumption of municipal water, as well as bathing in polluted lakes or beach water).
Indirectly – through the consumption of vegetables irrigated with contaminated water, as well as of fish or other animals that live in the polluted water or consume animals grown in the polluted water. This is many times more dangerous than being directly affected through consumption of water, because some pollutants bioaccumulate in fish and living organisms (their concentration in fish could be several orders of magnitude higher than their water concentration). Additionally, the toxins from the brown tide are strong and can travel via air, affecting homeowners close to the beach (3).

How water gets contaminated

Germs and chemicals can get in drinking water at the water’s source or in the distribution system after the water has already been treated (4). Harmful germs and chemicals can get in the water from many sources, including:

Fertilizers, pesticides, or other chemicals that have been applied to land near the water
Concentrated feeding operations (large industrial animal farms)
Manufacturing operations
Sewer overflows
Storm water
Wildlife
Rocks and soil that naturally have chemicals and minerals such as arsenic, radon, and uranium
Cracks in water pipes or other problems in the distribution system (4)

Main categories of water pollutants

Water may commonly be polluted by two main categories of pollutants (dissolved or suspended in water):

Chemicals – including natural or man-made (xenobiotic) chemicals that gets into a water body (by being dissolved or dispersed in the water) and reaching concentrations that raise serious health concerns; note that, similar to the case of air pollutants, the presence of such pollutants in water is not always obvious and may not be detected by our senses. Common problematic chemicals getting into water are pesticides, chlorinated solvents, petroleum chemicals, mercury, PCBs, dioxins and other persisting organic pollutants; as well as any of the other tens of thousands of chemicals used in industrial processes.

2. Living organisms

Pathogens – including a variety of living organisms (usually from animal waste) such as various species of viruses, bacteria, fungi and intestinal worms. Their presence in water, many times, remains unnoticed.
Algae – some types of algae are toxic and may overgrow due to the presence of nitrates and phosphates in runoff water (especially agricultural runoff); such overgrowth is usually referred to as “red tides” or “brown tides”. Their toxins may affect the food chain, including fish and birds, and ultimately humans. Oxygen depletion in polluted water is another serious problem responsible for killing fish all over the world (3).

Most common water pollution diseases

While the most common water pollution diseases involve poisoning episodes affecting the digestive system and/or causing human infectious diseases, water pollution may cause a large variety of health diseases including (3):

Infectious diseases caused by pathogens (usually microorganisms) from animal fecal origins, of which the most common occur in developing countries, including (3):

Typhoid
Giardiasis
Amoebiasis
Ascariasis
Hookworm

Diseases caused by polluted beach water, including (3):

Gastroenteritis
Diarrhea
Encephalitis
Stomach cramps and aches
Vomiting
Hepatitis
Respiratory infections

A series of less serious health effects could be associated to bathing in contaminated water (i.e. polluted beach water) including (3):

Rashes
Earaches
Pink eyes

Some people are more likely to get sick from germs and chemicals in water:

Infants
Young children
People who are pregnant
Older adults
People who have weakened immune systems, such as people living with HIV, getting chemotherapy treatment, or taking transplant medications (4)

Water and Climate Change

Climate change is primarily a water crisis. We feel its impacts through worsening floods, rising sea levels, shrinking ice fields, wildfires and droughts. However, water can fight climate change. Sustainable water management is central to building the resilience of societies and ecosystems and to reducing carbon emissions. Everyone has a role to play – actions at the individual and household levels are vital (5).

Water and climate change are inextricably linked. Extreme weather events are making water scarcer, more unpredictable, more polluted or all three. These impacts throughout the water cycle threaten sustainable development, biodiversity, and people’s access to water and sanitation.
Flooding and rising sea levels can contaminate land and water resources with saltwater or faecal matter, and cause damage to water and sanitation infrastructure, such as waterpoints, wells, toilets and wastewater treatment facilities.
Growing demand for water increases the need for energy-intensive water pumping, transportation, and treatment, and has contributed to the degradation of critical water-dependent carbon sinks such as peatlands. Water-intensive agriculture for food production, particularly meat, and for growing crops used as biofuels, can further exacerbate water scarcity.
Glaciers, ice caps and snow fields are rapidly disappearing. Meltwater feeds many of the great river systems. Volatility in the cryosphere can affect the regulation of freshwater resources for vast numbers of people in lowland areas.
Droughts and wildfires are destabilizing communities and triggering civil unrest and migration in many areas. Destruction of vegetation and tree cover exacerbates soil erosion and reduces groundwater recharge, increasing water scarcity and food insecurity (5).

Sustainable, affordable and scalable water solutions include:

Protecting natural buffers. Coastal mangroves and wetlands are effective and inexpensive natural barriers to flooding, extreme weather events and erosion, as the vegetation helps regulate water flow and binds the soil in flood plains, river banks and coastlines.
Harvesting rainwater. Rainwater capture is particularly useful in regions with uneven rainfall distribution to build resilience to shocks and ensure supplies for dry periods. Techniques include rooftop capture for small-scale use and surface dams to slow run-off to reduce soil erosion and increase aquifer recharge.
Adopting climate-smart agriculture. Using conservation techniques to improve organic matter to increase soil moisture retention; drip irrigation; reducing post-harvest losses and food waste; and, transforming waste into a source of nutrients or biofuels/biogas.
Reusing wastewater. Unconventional water resources, such as regulated treated wastewater, can be used for irrigation and industrial and municipal purposes. Safely managed wastewater is an affordable and sustainable source of water, energy, nutrients and other recoverable materials.
Harnessing groundwater. In many places, groundwater is over-used and polluted; in other places, it is an unknown quantity. Exploring, protecting and sustainably using groundwater is central to adapting to climate change and meeting the needs of a growing population.
Improving carbon storage. Peatlands store at least twice as much carbon as all of Earth’s forests. Mangrove soils can sequester up to three or four times more carbon than terrestrial soils. Protecting and expanding these types of environments can have a major impact on climate change (5).

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