From the physical and social well-being of an individual to the functioning of an ecosystem, health has many different meanings and applications. More than just the absence of disease, health implies a state of well-being. Ever since the origin of life, physical, chemical and biological factors have impacted the health or biological status of living things. And in response life has evolved immune systems, detoxification systems and redundancies to stave off infection, disease, and toxicity. As the world becomes more interconnected, and industrialized, diseases never seen in one part of the globe now threaten to devastate human, wildlife and plant populations, while industrial chemicals now contaminate life in the most remote regions. Maintaining health, whether ecosystem, human or microbial arguably presents one of the greatest challenges of the day.
Chemicals that mimic or antagonize the actions of naturally occurring estrogens are defined as having estrogenic activity (EA), which is the most common form of endocrine...
Gut reaction: environmental effects on the human microbiotaLast Updated on 2014-10-13 22:34:38This article, written by Melissa Lee Phillips, appeared first in Environmental Health Perspectives—the peer-reviewed, open access journal of the National Institute of Environmental Health Sciences.
The article is a verbatim version of the original and is not available for edits or additions by Encyclopedia of Earth editors or authors. Companion articles on the same topic that are editable may exist within the Encyclopedia of Earth.
Living with each of us—on our skin, in our mucosa, and in our gastrointestinal (GI) tract—are microorganisms whose numbers dwarf the number of our own cells and genes. Although some of these microbes are pathogens, most are harmless or even beneficial. The body’s assortment of microorganisms, collectively called the microbiota, is similar to an organ in that it performs functions essential for our survival. Some microbes produce... More »
BacteriaLast Updated on 2014-10-12 18:54:28
Bacteria are any of a very large group of single-celled microorganisms that display a wide range of metabolic types, geometric shapes and environmental habitats—and niches—of occurrence. Normally only several micrometers in length, bacteria assume the form of spheres, rods, spirals and other shapes. Bacteria are found in a very broad gamut of habitats; for example, bacterial extremophiles that thrive in such places as hot springs, arctic environments, radioactive waste, deep sea oil seeps, deep Earth crustal environments, hypersaline ponds and within other living organisms. There are approximately 50 million bacterial organisms in a single gram of typical surface soil. The worldwide bacterial biomass exceeds that of all plants and animals on Earth. However, the majority of bacteria have not yet been characterised,
Bacteria are members of the prokaryote... More »
Air quality in megacitiesLast Updated on 2014-09-18 16:40:27
Ambient air pollution in an increasingly urbanized world directly threatens the health of a large fraction of the world’s population. There is growing recognition that air-borne emissions from major urban and industrial areas influence both air quality and climate change on scales ranging from regional up to continental and global. Deteriorating urban air quality affects the viability of important natural and agricultural ecosystems in regions surrounding highly urbanized areas, and significantly influences regional atmospheric chemistry and global climate change. This challenge is particularly acute in the developing world where the rapid growth of megacities (cities having population equal to or more than 10 million) is producing atmospheric pollution of unprecedented severity and extent. For example, the deterioration of air quality is a problem that is directly experienced... More »
FluorineLast Updated on 2014-09-13 19:14:38Fluorine is a highly reactive chemical element with atomic symbol F. Having the atomic number nine, fluorine is the lightest halogen. Fluorine is a yellow-green gas which does not occur as a free, unreacted element in the natural environment. Under conditions of standard temperature and pressure, elemental fluorine forms a diatomic molecule with chemical formula F2. Chemically, fluorine is one of the strongest known oxidizing agents, and even more reactive and hazardous than chlorine. Its very high electron affinity causes fluorine to react directly with almost all other elements except for several of the Noble gases.
Previous Element: Oxygen
Next Element: Neon
Phase at Room Temp.
Density... More »
Fenugreek Last Updated on 2014-08-22 15:04:52
(Source: Saikat Basu, own work)
Species: Trigonella foenum-graecum
Binomial name: Trigonella foenum-graecum L.
Fenugreek (Trigonella) is the oldest medicinal plant in the world. Most popular species of this genus is Trigonella foenum-graecum, where the term “foenum-graecum” means ‘Greek hay’ pointing to its use as a forage crop in the past, fenugreek is grown mainly as a spice crop in the recent times. The plant is believed to be native to the Mediterranean region1-6. There are several controversies regarding the origin of the fenugreek plant for which no proper theory as to the... More »
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