Water pollution sources, impacts, and mitigation strategies

Nitrate, Aluminum, And Lead in Drinking Water

Three mayor harmful chemicals that affect water's natural condition are nitrate, aluminum, and lead. In recent years, public fears over the contamination of drinking water by these and other contaminants have grown. Certainly, the public is right to be concerned about the possible health effects of aluminum, nitrate, and lead. Aluminum has long been linked with an increased risk of Alzheimer's disease, bone diseases and anemia. Nitrates are known to have gastric effects, neurological implications, as well as other effects on human health. Lead is well documented to play a role in intellectual retardation, and also impacts abdominal pain, and has other health effects. Aluminum, nitrate, and lead in the human water supply pose significant threats to public health.

Today, domestic water supplies across the world vary enormously in quality. In Great Britain, tap water (which comes from groundwater, reservoirs, and rivers) is treated, and must meet water quality standards for the removal of harmful chemicals like aluminum, lead, and nitrates, as well as reduce the levels of disease-causing microorganisms (Walker). Similarly, tap water in the United States is treated for public safety. However, a number of individuals in the United States drink water from wells, potentially exposing them to harmful chemicals and microorganisms (Schubert, Knobeloch, Kanarek and Anderson). Individuals in less developed regions face an even larger problem with water contamination. Given the prevalence of unsafe drinking water worldwide, it remains crucial to understanding the potential health effects of harmful chemicals in water. Three of the most harmful chemicals found in human drinking water are aluminum, lead, and nitrate. The effects that these three chemicals (nitrate, lead and aluminum) in drinking water have on human health and well-being will be examined in this paper.

Aluminum

The majority of scientific evidence about the health effects of aluminum arisentered on aluminum's neurotoxic effects. The risk of Alzheimer's disease has been shown to be 1.5 times higher in areas where aluminum concentrations in drinking water were greater than 0.11 mg/l than in areas where the concentration was below 0.01 mg/l. Further, patients on renal dialysis that were exposed to water with high aluminum concentrations have shown evidence of a so-called "dialysis dementia" that is presumably linked with high levels of aluminum in drinking water (Walker).

However, studies have not been completely conclusive about the degree to which aluminum can cause neurotoxicity (Walker). Further, the toxicity that is often attributed to aluminum may be influenced by other constituents in water such as calcium, pH, and fluoride. As such, the link between aluminum and brain disorders remains to be conclusively established (Rifat).

In addition to its' neurotoxic effects, aluminum in drinking water may have numerous significant other health effects. These effects include links between aluminum and bone disease and anemia.

Interestingly, aluminum in drinking water may be introduced into the water supply by water treatment processes themselves. Aluminum sulphate is added as a coagulant that removes suspended matter during the water treatment process in many facilities. The aluminum nitrate is then removed through filtration and clarification, but trace amounts may remain. In the European community, the maximum acceptable concentration of aluminum in drinking water in the UK is 0.2 mg/l, based on the incidence of problems with dirty water, rather than health implications (Walker).

Nitrate

Nitrate is known to have a number of gastric, neurological and other effects on human health. The World Health Organizations' permissible limit for nitrate in drinking water is 50 mg/l. In many areas of the world this limit is exceeded, and in India concentrations that exceed 500 mg/l in drinking water are common (Gupta et al.).

Links between nitrate and gastric effects are well documented. In one study by Gupta et al., children with high nitrate levels in drinking water in India were demonstrated to have recurrent diarrhea.

Nitrate within the water supply has also been linked to gastric cancer and nitrate in the diet. High rates of nitrate exposure are linked to a higher risk of gastric cancer in areas like Denmark, Italy and Hungary. However, these findings are not universally consistent, and British studies have failed to maintain this link between high levels of nitrate exposure and gastric cancer (Walker).

In water, nitrate is converted into nitrate, which in turn can combine with fetal hemoglobin and then be converted into methaemoglobin. In high enough concentrations, methaemoglobin had been reported to cause cyanosis and therefore result in children's deaths (Walker).

Nitrate has also been linked to a number of other heath concerns. These include gastric lymphoma, thyroid disorder, birth defects, and spontaneous abortion (Schubert, Knobeloch, Kanarek and Anderson).

In adults, nitrate may have an effect on the brain. Neurological effects of nitrate exposure in drinking water have been suggested as a possible health effect of nitrate exposure in adults.

Lead

The effect of lead on human health is well-known. Lead often enters the water supply through plumbing in homes that were built prior to 1964. As such, people in older homes with acidic water are at the greatest risk for lead poisoning (Walker). In the United States, lead poisoning is a major environmental health problem that affects children (Government Printing Press).