Health effects related to contaminants in drinking water can be divided into two categories: those that cause acute effects and those that cause chronic effects.
Acute effects are usually seen within a short time after exposure to a substance. Acute effects may result from water containing pathogens such as bacteria and viruses, or they may result from a single large exposure to a chemical contaminant. Acute health effects are generally reversible as long as the contaminant of concern is removed and appropriate medical treatment is given.
An acute effect may occur, for example, when a person consumes water containing pathogenic bacteria or viruses. That individual will usually develop symptoms within a relatively short period of time (generally days or weeks) after ingesting the water. Copper is another example of a chemical contaminant that can cause acute health effects. While some copper is necessary, drinking water containing large amounts of copper can cause cramps or abdominal pains especially in young children or those not used to drinking water with elevated copper levels.
Chronic effects result from repeated exposure to a substance over a long period of time (generally months or years), and the effects may not be immediately apparent. The longer a person is exposed to a particular substance in drinking water, the more likely that health effects will develop. Chronic health effects may result if you are using contaminated water as your principal water supply for a long or extended period of time (generally years or decades).
Even very small amounts of contaminants, such as pesticides, arsenic, and lead, may increase the likelihood of developing certain types of long-term health effects. When dealing with substances that cause chronic health effects, it can be difficult to determine how much of a substance is too much; it is assumed that at any dose some adverse health effects may be possible. Drinking-water standards are developed to provide a reasonably low risk of developing any adverse health effects; risk levels usually range from one in 10,000 people to one in a million.
As with other health-related issues, certain individuals or groups of individuals may be more at risk than others. While drinking-water standards have been established for some of the more common chemicals found in groundwater, there are many others for which standards have not yet been developed. To complicate matters further, little is known regarding multiple contaminants in water and the combined effect that they may have on people’s health.
If you suspect drinking-water quality may be impacting your health, consult your local health department or primary physician for more information.