Water Pollution's Deadly Impact On Human Health

Water pollution is a global issue that poses a serious threat to human health and the environment. It occurs when water becomes contaminated with various substances, such as chemicals, waste, plastic, and other pollutants, making it unsafe for human use and disrupting aquatic ecosystems. This contamination can lead to the spread of waterborne diseases, including cholera, typhoid, and dysentery, which cause the deaths of over 500,000 people worldwide annually. The problem is exacerbated by factors such as industrialization, population growth, and the improper disposal of waste, with over 80% of the world's sewage ending up in seas and rivers untreated. These issues are particularly prevalent in countries experiencing rapid economic expansion, and the effects disproportionately impact low-income communities, who are often located closest to the most polluting industries. As water is an essential resource for all life on Earth, addressing water pollution is crucial for safeguarding human health and ensuring sustainable development.

Water-borne diseases: cholera, dysentery, typhoid, and polio

Water pollution is a major cause of waterborne diseases, which afflict millions of people, particularly those in developing countries who lack access to safe water. Cholera, dysentery, typhoid, and polio are among the most common and dangerous waterborne diseases.

Cholera is a waterborne disease that can cause deadly epidemics, as seen in the 2016 outbreak in Uganda, where hundreds of people were infected by drinking contaminated water from the Cheptui River. Cholera causes watery diarrhoea, and severe dehydration can be life-threatening.

Dysentery is another waterborne disease caused by bacteria, viruses, or parasites in contaminated food and water. It is characterised by severe diarrhoea, with blood or mucus in the stool, and can be life-threatening if fluid loss is not addressed. Poor hygiene, such as not washing hands, is a major contributor to the spread of dysentery.

Typhoid fever is a serious waterborne disease that has claimed lives and affected hundreds of people in outbreaks linked to contaminated drinking water sources. Inadequate sanitation and hygiene, such as the presence of faecal material and garbage in water sources, contribute to the spread of typhoid.

Polio is a disabling and life-threatening disease that can be transmitted through contaminated water. While polio has been eradicated in many parts of the world through vaccination, it still poses a risk in areas with inadequate sanitation and low immunization rates.

To prevent waterborne diseases, it is crucial to ensure access to clean and safe drinking water, improve sanitation and hygiene practices, and promote health education and vaccination. These measures can effectively reduce the impact of water pollution on public health and save lives.

Inadequate water supply, sanitation, and hygiene

Diarrhoeal diseases are a significant cause of death, with an estimated 502,000 deaths attributed to inadequate drinking water, 280,000 to inadequate sanitation, and 297,000 to poor hand hygiene in 2012. This amounts to 842,000 diarrhoeal deaths, or 58% of all diarrhoeal disease deaths, with a further 361,000 preventable deaths in children under five years old. In 2016, an estimated 829,000 WASH-attributable deaths from diarrhoeal diseases occurred, with 297,000 deaths in children under five. Diarrhoea is largely preventable, and the deaths of 395,000 children under five could be avoided each year with improved water safety, sanitation, and hand hygiene.

In addition to diarrhoeal diseases, inadequate WASH is linked to other health issues such as respiratory infections, malnutrition, schistosomiasis, malaria, soil-transmitted helminth infections, and trachoma. These issues contribute to the global burden of disease, with WASH-related deaths and disabilities impacting millions of people annually.

Unsafe drinking water is often contaminated with faeces, posing a significant health risk. In 2022, 1.7 billion people used a drinking water source contaminated with faeces, while 2.2 billion lacked access to safely managed drinking water services. The lack of access to safe drinking water and sanitation facilities, as well as poor hygiene practices, contribute to the high number of deaths and illnesses associated with inadequate WASH.

Chemical and industrial pollutants: lead, arsenic, and fluoride

Lead, arsenic, and fluoride are chemical and industrial pollutants that can have severe health impacts, sometimes leading to fatalities. Here is a detailed overview of the effects of these contaminants:

Lead

Lead is a toxic heavy metal that can be found in various sources, including drinking water. While bathing or showering with lead-containing water is generally considered safe, as human skin does not absorb it, ingestion of lead through contaminated water can pose serious health risks. Lead accumulates in the body over time, storing in the bones along with calcium. During pregnancy, lead can be released from the mother's bones and used in the formation of the fetus's bones, potentially harming the developing child. Infants consuming milk formula made with lead-contaminated water are particularly vulnerable, as they can receive a significant proportion of their lead exposure from this source.

Even low levels of lead in children's blood can result in behavioural problems, learning difficulties, and impaired growth. In rare cases, ingestion of lead can cause seizures, comas, and even death. Lead exposure can be mitigated by using only cold water for drinking, cooking, and making baby formula, as boiling does not remove lead. Regularly flushing pipes and cleaning faucet screens can also help reduce lead exposure.

Arsenic

Arsenic, particularly in its inorganic form, is highly toxic and a confirmed carcinogen. Long-term exposure to inorganic arsenic, primarily through drinking water and food, can lead to chronic arsenic poisoning, causing skin lesions and skin cancer. It has also been associated with cardiovascular disease and diabetes. In utero and early childhood exposure to arsenic has been linked to adverse effects on cognitive development and increased mortality in young adults.

The greatest threat of arsenic exposure comes from contaminated groundwater, which is then used for drinking, food preparation, and irrigation of crops. Fish, shellfish, meat, poultry, dairy products, and cereals can also contain arsenic, although exposure from these dietary sources is generally lower compared to contaminated water. The immediate symptoms of acute arsenic poisoning include vomiting, abdominal pain, and diarrhoea, followed by more severe symptoms such as numbness, muscle cramping, and, in extreme cases, death.

Fluoride

Fluoride is added to public drinking water in some parts of the world, including the United States, to help prevent tooth decay. However, the practice has sparked controversy due to concerns about its potential health effects. While fluoride is naturally present in soil, air, and water, the levels can vary significantly. Excessive exposure to fluoride can lead to a condition called skeletal fluorosis, where fluoride accumulates in the bones, causing joint stiffness, pain, and weakened bones. In children, excessive fluoride intake can cause dental fluorosis, resulting in abnormal tooth enamel formation.

Microbial contamination: faecal matter in drinking water

Microbial contamination of drinking water is a significant issue, with 1.7 billion people using a drinking water source contaminated with faeces in 2022. Faecal contamination of water poses a severe health risk, as it can transmit diseases such as cholera, typhoid, and dysentery.

Fecal indicator bacteria (FIB) have been used for over 150 years to indicate faecal contamination of water and the associated health risks. Escherichia coli (E. coli) and certain Enterococcus species, such as E. faecalis and E. faecium, are the primary representatives of FIB. However, these bacteria cannot identify the origins or sources of contamination, which has prompted the development of microbial source tracking (MST) methods to pinpoint the exact causes of faecal pollution.

The presence of faecal matter in drinking water increases the load of chemical, biological, and organic contaminants. This additional selective pressure on the aquatic microbial community promotes the enrichment of certain microbes while suppressing others. As a result, the overall diversity of the aquatic microbial community is significantly reduced in severely polluted water.

The health risks associated with faecal contamination depend on the specific pathogens present and their concentrations. Enteric viruses, particularly human noroviruses, are a significant driver of gastrointestinal illness from recreational water exposures. Additionally, the recognition that sewage contamination of water sources spreads diseases such as cholera and typhoid has led to the need for effective methods to ascertain the presence of sewage in drinking water.

Access to safe and affordable drinking water is a fundamental human right and a key Sustainable Development Goal. In 2022, 6 billion people used safely managed drinking-water services, while 2.2 billion people lacked access to these services. The inadequate management of wastewater and the natural presence of chemicals in groundwater further exacerbate the issue of drinking water contamination.

Natural contaminants: chemicals in groundwater

While groundwater often appears clear and clean, it can contain natural and human-induced contaminants. Natural contaminants in groundwater can include chemicals such as arsenic, radon, boron, and fluoride, which are present in certain types of soil and rock formations. As groundwater flows through the ground, it can dissolve metals like iron and manganese, which may later be found in high concentrations.

Arsenic, for example, occurs naturally in some soils and can be found in groundwater at low concentrations. In 2021, more than 800 drinking water wells in California exceeded the federal standard for arsenic levels. Arsenic contamination can pose significant health risks, with long-term exposure potentially leading to skin lesions, peripheral neuropathy, cardiovascular disease, and an increased risk of certain cancers.

Radon is another natural contaminant that can be found in groundwater. Radon is a radioactive gas that occurs naturally as a result of the decay of uranium in rocks and soil. It can dissolve in water and be released into the air when water is used, posing health risks such as lung cancer if inhaled over prolonged periods.

Boron is an essential micronutrient, but it can be toxic to plants at slightly higher concentrations. It can occur naturally in groundwater, particularly in areas with certain geological characteristics, such as marine sedimentary rocks.

Fluoride is also a natural chemical that can be found in groundwater. While it is often added to municipal water supplies to promote dental health, excessive amounts can lead to dental fluorosis, a condition that affects the teeth.

In addition to these natural contaminants, human activities can introduce various chemicals and pollutants into groundwater sources. Leaking underground fuel tanks, industrial discharges, agricultural practices, and inadequate wastewater treatment can all contribute to groundwater contamination, further exacerbating the health risks associated with consuming contaminated water.

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