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Maximum Contaminant Level
Maximum contaminant levels (MCLs) are standards that are set by the United States Environmental Protection Agency (EPA) for drinking water quality.Joseph Cotruvo, Victor Kimm, Arden Calvert“Drinking Water: A Half Century of Progress.”EPA Alumni Association. March 1, 2016. An MCL is the legal threshold limit on the amount of a substance that is allowed in public water systems under the Safe Drinking Water Act (SDWA). The limit is usually expressed as a concentration In chemistry, concentration is the abundance of a constituent divided by the total volume of a mixture. Several types of mathematical description can be distinguished: '' mass concentration'', '' molar concentration'', '' number concentration'', ... in milligrams or micrograms per liter of water. Federal MCL development To set a maximum contaminant level for a contaminant, EPA first determines how much of the contaminant may be present with no adverse health effects. This level is called the ''maximum conta ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Standardization
Standardization (American English) or standardisation (British English) is the process of implementing and developing technical standards based on the consensus of different parties that include firms, users, interest groups, standards organizations and governments. Standardization can help maximize compatibility, interoperability, safety, repeatability, efficiency, and quality. It can also facilitate a normalization of formerly custom processes. In social sciences, including economics, the idea of ''standardization'' is close to the solution for a coordination problem, a situation in which all parties can realize mutual gains, but only by making mutually consistent decisions. Divergent national standards impose costs on consumers and can be a form of non-tariff trade barrier. History Early examples Standard weights and measures were developed by the Indus Valley civilization.Iwata, Shigeo (2008), "Weights and Measures in the Indus Valley", ''Encyclopaedia of the History ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tooth Discoloration
Tooth discoloration is abnormal tooth color, hue or translucency. External discoloration is accumulation of stains on the tooth surface. Internal discoloration is due to absorption of pigment particles into tooth structure. Sometimes there are several different co-existent factors responsible for discoloration. Normal tooth shade The appearance and perception of a tooth is the result of a complex interaction of factors such as lighting conditions, translucency, opacity, light scattering, gloss and the human eye and brain. Of these, the intrinsic pigmentation of a tooth is the most influential, which in turn is determined by genetic and natural factors. Light hitting a tooth undergoes reflection, absorption and transmission by varying degrees in each tissue layer of the tooth substance. Reflected light detected by the human eye determines the perceived appearance of a tooth. Teeth have a thin enamel layer on the outer surface. The enamel layer is whiter and semitransparen ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Environmental Law In The United States
Environment most often refers to: __NOTOC__ * Natural environment, referring respectively to all living and non-living things occurring naturally and the physical and biological factors along with their chemical interactions that affect an organism or a group of organisms Other physical and cultural environments *Ecology, the branch of ethology that deals with the relations of organisms to one another and to their physical surroundings *Environment (systems), the surroundings of a physical system that may interact with the system by exchanging mass, energy, or other properties. *Built environment, constructed surroundings that provide the settings for human activity, ranging from the large-scale civic surroundings to the personal places *Social environment, the culture that an individual lives in, and the people and institutions with whom they interact *Market environment, business term Arts, entertainment and publishing * Environment (magazine), ''Environment'' (magazine), a p ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Maximum Concentration
is the maximum (or peak) serum concentration that a drug achieves in a specified compartment or test area of the body after the drug has been administered and before the administration of a second dose. It is a standard measurement in pharmacokinetics. Description is the opposite of , which is the minimum (or trough) concentration that a drug achieves after dosing. The related pharmacokinetic parameter is the time at which the is observed. After an intravenous administration, and are closely dependent on the experimental protocol, since the concentrations are always decreasing after the dose. But after oral administration, and are dependent on the extent, and the rate of drug absorption and the disposition profile of the drug. They could be used to characterize the properties of different formulations in the same subject. Short term drug side effects are most likely to occur at or near the , whereas the therapeutic effect of drug with sustained duration of action u ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Maximum Residue Limit
The maximum residue limit (also maximum residue level, MRL) is the maximum amount of pesticide residue that is expected to remain on food products when a pesticide is used according to label directions, that will not be a concern to human health. Determination The MRL is usually determined by repeated (on the order of 10) field trials, where the crop has been treated according to good agricultural practice (GAP) and an appropriate pre harvest interval or withholding period has elapsed. For many pesticides this is set at the limit of determination (LOD) – since only major pesticides have been evaluated and understanding of acceptable daily intake (ADI) is incomplete (i.e. producers or public bodies have not submitted MRL data – often because these were not required in the past). LOD can be considered a measure of presence/absence, but certain residues may not be quantifiable at very low levels. For this reason the limit of quantification (LOQ) is often used instead of the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Drinking Water Quality In The United States
Drinking water quality in the United States is generally safe. In 2016, over 90 percent of the nation's community water systems were in compliance with all published United States Environmental Protection Agency, U.S. Environmental Protection Agency (US EPA) standards. Over 286 million Americans get their tap water from a community water system. Eight percent of the community water systems—large municipal water systems—provide water to 82 percent of the US population. The Safe Drinking Water Act requires the US EPA to set standards for drinking water quality in Public water system, public water systems (entities that provide water for human consumption to at least 25 people for at least 60 days a year). Enforcement of the standards is mostly carried out by state health agencies. States may set standards that are more stringent than the federal standards. Despite improvements in water quality regulations, disparities in access to clean drinking water persist in marginalized commu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Perfluorononanoic Acid
Perfluorononanoic acid, or PFNA, is a synthetic perfluorinated carboxylic acid and fluorosurfactant that is also a persistent organic pollutant. Chemistry and properties In acidic form it is a highly reactive strong acid. In its conjugate base form as a salt it is stable and commonly ion paired with ammonium. In the commercial product Surflon S-111 (CAS 72968-3-88) it is the primary compound present by weight. PFNA is used as surfactant for the production of the fluoropolymer polyvinylidene fluoride.Supporting Information (PDF) It is produced mainly in Japan by the of a linear |
National Secondary Drinking Water Regulations
In the United States, public drinking water is governed by the laws and regulations enacted by the federal and state governments. Certain ordinances may also be created at a more local level. The Safe Drinking Water Act (SDWA) is the principal federal law. The SDWA authorizes the United States Environmental Protection Agency (EPA) to create and enforce regulations to achieve the SDWA goals. Federal requirements The Safe Drinking Water Act is the principal federal law governing public water systems. These systems provide drinking water through pipes or other constructed conveyances to at least 15 service connections, or serve an average of at least 25 people for at least 60 days a year. As of 2017 there are over 151,000 public water systems. * Approximately 52,000 Community Water Systems serve the majority of the U.S. population * Approximately 85,000 systems are non-transient, non-community water systems (such as schools, factories, office buildings, and hospitals that operate th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
United States Environmental Protection Agency
The Environmental Protection Agency (EPA) is an independent agency of the United States government tasked with environmental protection matters. President Richard Nixon proposed the establishment of EPA on July 9, 1970; it began operation on December 2, 1970, after Nixon signed an executive order. The order establishing the EPA was ratified by committee hearings in the House and Senate. The agency is led by its administrator, who is appointed by the president and approved by the Senate. The current administrator is Lee Zeldin. The EPA is not a Cabinet department, but the administrator is normally given cabinet rank. The EPA has its headquarters in Washington, D.C. There are regional offices for each of the agency's ten regions, as well as 27 laboratories around the country. The agency conducts environmental assessment, research, and education. It has the responsibility of maintaining and enforcing national standards under a variety of environmental laws, in consultat ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Water Purification
Water purification is the process of removing undesirable chemicals, biological contaminants, suspended solids, and gases from water. The goal is to produce water that is fit for specific purposes. Most water is purified and disinfected for human consumption (drinking water), but water purification may also be carried out for a variety of other purposes, including medical, pharmacological, chemical, and industrial applications. The history of water purification includes a wide variety of methods. The methods used include physical processes such as filtration, sedimentation, and distillation; biological processes such as slow sand filters or biologically active carbon; chemical processes such as flocculation and chlorination; and the use of electromagnetic radiation such as ultraviolet light. Water purification can reduce the concentration of particulate matter including suspended particles, parasites, bacteria, algae, viruses, and fungi as well as reduce the concentration ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Health Effect
Health effects (or health impacts) are changes in health resulting from exposure to a source. Health effects are an important consideration in many areas, such as hygiene, pollution studies, occupational safety and health, ( utrition and health sciences in general. Some of the major environmental sources of health effects are air pollution, water pollution, soil contamination, noise pollution and over-illumination. A non-stochastic or deterministic health effect has a severity that is dependent on dose and is believed to have a threshold level for which no effect is seen. Stochastic health effects occur by chance, generally occurring without a threshold level of dose, whose probability is proportional to the dose and whose severity is independent of the dose, such as cancer and genetic effects. Occasionally, lack of exposure to certain effectors has detrimental consequences on an individual's health. Examples of such effectors include sunlight and exercise. See also * Environ ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
