Ecotoxicology is the environmental science sub-discipline that melds the fields of ecology and toxicology. The word derives from the Greek words eīkos (meaning household), toxicos (meaning poisonous), and logia (meaning study of). Its focus concerns monitoring, investigation and assessment of adverse effects of chemical (and radiological) substances on ecological systems and their biotic components and processes.
A heavy metal is any one of a number of elements that exhibit metallic properties, which includes transition metals lanthanides actinides as well as the metalloids Arsenic and...
HerbicideLast Updated on 2014-10-26 16:45:24A herbicide is any of a number of chemical substances intended to kill vegetation. Since the vast majority of herbicides are non-selective in their lethal action, there may be widespread adverse ecological consequences from their use. These outcomes include not only organism death, but may involve mutagenic, developmental and carcinogenic effects to animals and plants.
Herbicides are in broad use for agriculture, golf courses, utility corridors, residential and other land uses. The earliest herbicides were inorganic chemical substances, although modern herbicides are dominated by organic compounds. Presently, there is massive application of chemical herbicides; in the USA alone 480 million kilograms are applied annually.
Widespread herbicide use beginning in the 1940s is responsible for numerous species extinctions, including birds, amphibians, fish and arthropods. In many cases,... More »
CellsLast Updated on 2014-06-30 14:15:10
Cells are the smallest component of the body that can perform all of the basic life functions. Each cell performs specialized functions and plays a role in the maintenance of homeostasis. While each cell is an independent entity, it is highly affected by damage to neighboring cells. These various cell types combine to form tissues, which are basically collections of specialized cells that perform a relatively limited number of functions specific to that type of tissue. The human body is made up of several trillion cells; these cells are of various types, which can differ greatly in size, appearance and function.
While there are approximately 200 types of cells, they all have similar features: cell membrane, cytoplasm, organelles, and nucleus. The only exception is that the mature red blood cell does not contain a nucleus. In general, toxins can injure any of the components of... More »
SeleniumLast Updated on 2014-06-29 16:59:07
Selenium is a gray, metallic element. Its atomic number is 34 and its symbol is Se. The Swedish scientist Jons Jacob Berzelius discovered selenium in 1817. In studying the sulfuric acid produced in a particular Swedish factory, he discovered an impurity which he eventually identified as selenium. Selenium occurs in three distinct forms: as a non-crystalline, gray metal; it can form as a deep red to black powder; and it can form as red crystals. It is stable in air and in water. Selenium is actually an important trace element to mammals and some plants. Too much selenium in a mammal’s diet is poisonous and has been shown to cause deformities. When there is not enough selenium, a mammal can also have health problems. For example, sheep that graze in areas with too little selenium in the soil eventually have a problem known as “white muscle disease.” Lack of selenium... More »
PfiesteriaLast Updated on 2014-06-15 18:34:27This article was researched and written by a student at Mount Holyoke College participating in the Encyclopedia of Earth's (EoE) Student Science Communication Project. The project encourages students in undergraduate and graduate programs to write about timely scientific issues under close faculty guidance. All articles have been reviewed by internal EoE editors, and by independent experts on each topic.
Algal blooms were once considered solely a natural phenomenon in coastal ecosystems. But, in recent years, the frequency and severity of algal blooms have increased dramatically, due primarily to anthropogenic activities that create agricultural and sewage runoff resulting in nutrient loading in coastal ecosystems. This runoff and nutrient loading stimulates the growth of many algal species. Algal blooms that have harmful implications to the surrounding environment and to human... More »
Public Health Statement for MercuryLast Updated on 2013-10-01 23:36:56This article is a verbatim version of the original and is not available for edits or additions by EoE editors or authors. Companion articles on the same topic that are editable may exist within the EoE.
This Public Health Statement is the summary chapter from the Toxicological Profile for Mercury. It is one in a series of Public Health Statements about hazardous substances and their health effects. A shorter version, the ToxFAQs™, is also available. This information is important because this substance may harm you. The effects of exposure to any hazardous substance depend on the dose, the duration, how you are exposed, personal traits and habits, and whether other chemicals are present. For more information, call the ATSDR Information Center at 1-888-422-8737.
This public health statement tells you about... More »
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