Abstract
Water quality criteria pollutants can come from both man-made and natural resources. Pollutants are numerical variables and serve as a basis for regulatory laws governing water treatment and distribution. Maximum Contaminant Levels are also defined by quantitative figures and serve as a warning against prolonged exposure to contaminants above accepted levels in water. This document reveals the key player in setting the standards for water management and a few examples of harmful contaminants. The purpose here is to distinguish between criteria pollutants and MCL’s. In completing the research for this topic, it was determined that some contaminants come from factories and runoff from herbicides. On the other hand, others are deliberately added to the water supply. For instance, Benzene is discharged from factories, whereas Acrylamide is added (within acceptable levels) during sewage water treatment. Of the three references cited, the two most helpful in completing this document were the Environmental Protection Agency Website and a 600 page document from the World Health Organization about water quality assessments.
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"Water Quality Criteria Pollutants and Maximum Contaminant Levels".
The quality of water is something that some people may take for granted. They may not realize that many monitoring, assessment and management protocols are at play even before getting water from the kitchen sink. Consequently, the quality standards, identified pollutants and monitoring (to enforce regulations) must constantly evolve to meet the anthropogenic demands imposed on water, one of Earth’s precious natural resources. The purpose of this document is to discuss how water quality standards are determined. In addition, the difference between water quality criteria pollutants and maximum contaminant levels will be explained.
Water quality can be thought of as how suitable the water is for use based on characteristics that can be classified in three ways: biological, physical and chemical. The federal government has set standards against which water quality can be measured so that overall safety can be assessed prior to distribution among populations. The Environmental Protection Agency implements the Safe Drinking Water Act. The agency also reports quality criteria that include scientific information about chemical concentrations in water. This is known as the National Recommended Water Quality Criteria (U.S. EPA). Aquatic Life and Human Health are the two main concerns for which water quality standards are set. Criteria include the amounts of various pollutants. Examples of pollutants are chlorobenzene, toluene and vinyl chloride among many others. The standards for water quality are determined based on these pollutants and their quantitative figures. The Maximum Contaminant Levels can be defined as the greatest amount of contaminants that can be allowed in the water supply without causing harm to living things. There are close to 100 M.C.L’s that must be updated regularly as they are subject to the strict rules of the Safe Drinking Water Act. Also, these represent chemicals that are thought to pose the most serious risk (http://extoxnet.orst.edu/faqs/safedrink/mcl.htm).
Secondly, they are determined by the adverse health effects that are caused by the chemicals included in this list as well as the amount of exposure needed to cause the damage. Finally, the organic and inorganic chemicals that make up the M.C.L’s are grouped according to those that cause cancer, those that do not cause cancer and those that might possibly be carcinogenic. The difference between water quality criteria pollutants and M.C.L.’s is quite simple to grasp. The criteria pollutant is the element causing contamination due to its adverse effects which can be measured. Pollutants have various potencies and behavioral chemical properties both in living things and in water. This explains why two different contaminants such as Benzene and Arsenic for instance, would have two different MCL’s. This is also what determines the maximum level of contamination that is allowable in water. The maximum amounts for these examples are: .005 for Benzene and .010 for Arsenic. Long term exposure to any amount of these contaminants above the MCL will have hazardous effects on humans such as increased risk of cancer, anemia, skin damage and decreased blood platelets. While many contaminants come from metal refineries and factories, some are added to water (according to regulated standards) in the process of wastewater treatment or for controlling microbes (U.S. EPA).
In conclusion, the criteria pollutants serve as recommendations for what is acceptable in water. They are used by agencies which assume the responsibility of adhering to laws pertaining to water pollution. Because of the potential health risks both mild and sever, MCL’s are set and regularly updated as quantitative figures that can be viewed as warnings. With this in place, laws governing water treatment and circulation can be effectively created and enforced.
- Chapman, D. (1996) Water Quality Assessments – A Guide to Use of Biota, Sediments and Water in Environmental Monitoring – Second Edition. World Health Organization. United Nations Educational, Scientific and Cultural Organization. University Press, Cambridge: Retrieved from
- MCLs and MCLGs: Establishing Maximum Contaminant Levels (2013)
In Etoxnet FAQs from http://extoxnet.orst.edu/faqs/safedrink/mcl.htm- United States Environment Protection Agency (May, 2009). National Primary Drinking Water Regulations from http://www.epa.gov
- MCLs and MCLGs: Establishing Maximum Contaminant Levels (2013)
