LINK / CITE ADD TO WORD LIST. adjective. The definition of harmful is something that causes damage or is able to be hurtful. A chemical that causes you to become sick is an example of a chemical that would be described as harmful. causing or able to cause harm; hurtful. adjective.
The most common way to become infected with giardia is after swallowing contaminated water. Giardia parasites are found in lakes, ponds, rivers and streams worldwide, as well as in municipal water supplies, wells, cisterns, swimming pools, water parks and spas. Ground and surface water can become contaminated from agricultural runoff, wastewater discharge or animal feces.
Contaminated water supplies: Giardia lamblia is one of the most common causes of water-borne diarrhea outbreaks. Sources of contaminated water include public facilities that improperly filter and treat water, water in developing countries, or rivers and lakes used by hikers.