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Heptachlor
Heptachlor is an organochlorine compound that was used as an insecticide. Usually sold as a white or tan powder, heptachlor is one of the cyclodiene insecticides. In 1962, Rachel Carson's ''Silent Spring'' questioned the safety of heptachlor and other chlorinated insecticides. Due to its highly stable structure, heptachlor can persist in the environment for decades. In the United States, the Environmental Protection Agency has limited the sale of heptachlor products to the specific application of fire ant control in underground transformers. The amount that can be present in different foods is regulated.Robert L. Metcalf "Insect Control" in ''Ullmann’s Encyclopedia of Industrial Chemistry'', Wiley-VCH, Weinheim, 2002. Synthesis Analogous to the synthesis of other cyclodienes, heptachlor is produced via the Diels-Alder reaction of hexachlorocyclopentadiene and cyclopentadiene. The resulting adduct is chlorinated followed by treatment with hydrogen chloride in nitromethane in t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Persistent Organic Pollutant
Persistent organic pollutants (POPs) are organic compounds that are resistant to degradation through chemical, biological, and photolytic processes. They are toxic and adversely affect human health and the environment around the world. Because they can be transported by wind and water, most POPs generated in one country can and do affect people and wildlife far from where they are used and released. The effect of POPs on human and environmental health was discussed, with intention to eliminate or severely restrict their production, by the international community at the Stockholm Convention on Persistent Organic Pollutants in 2001. Most POPs are pesticides or insecticides, and some are also solvents, pharmaceuticals, and industrial chemicals. Although some POPs arise naturally (e.g. from volcanoes), most are man-made. The "dirty dozen" POPs identified by the Stockholm Convention include aldrin, chlordane, dieldrin, endrin, heptachlor, HCB, mirex, toxaphene, PCBs, DDT ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chlordane
Chlordane, or chlordan, is an organochlorine compound that was used as a pesticide. It is a white solid. In the United States, chlordane was used for termite-treatment of approximately 30 million homes until it was banned in 1988. Chlordane was banned 10 years earlier for food crops like corn and citrus, and on lawns and domestic gardens.Robert L. Metcalf "Insect Control" in ''Ullmann’s Encyclopedia of Industrial Chemistry'', Wiley-VCH, Weinheim, 2002. Like other chlorinated cyclodiene insecticides, chlordane is classified as an organic pollutant hazardous for human health. It is resistant to degradation in the environment and in humans/animals and readily accumulates in lipids (fats) of humans and animals.Agency for Toxic Substances & Disease Registry (ATSDR). Toxic Substances Portal: Chlordane. Last updated September, 2010 nline Available at URL: https://wwwn.cdc.gov/TSP/index.aspx?toxid=62 Exposure to the compound has been linked to cancers, diabetes, and neurological ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Organochlorine Compound
Organochlorine chemistry is concerned with the properties of organochlorine compounds, or organochlorides, organic compounds that contain one or more carbon–chlorine bonds. The chloroalkane class (alkanes with one or more hydrogens substituted by chlorine) includes common examples. The wide structural variety and divergent chemical properties of organochlorides lead to a broad range of names, applications, and properties. Organochlorine compounds have wide use in many applications, though some are of profound environmental concern, with TCDD being one of the most notorious. Organochlorides such as trichloroethylene, tetrachloroethylene, dichloromethane and chloroform are commonly used as solvents and are referred to as "chlorinated solvents". Physical and chemical properties Chlorination modifies the physical properties of hydrocarbons in several ways. These compounds are typically denser than water due to the higher atomic weight of chlorine versus hydrogen. They have highe ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Epoxidation
In organic chemistry, an epoxide is a cyclic ether, where the ether forms a three-atom ring: two atoms of carbon and one atom of oxygen. This triangular structure has substantial ring strain, making epoxides highly reactive, more so than other ethers. They are produced on a large scale for many applications. In general, low molecular weight epoxides are colourless and nonpolar, and often volatile. Nomenclature A compound containing the epoxide functional group can be called an epoxy, epoxide, oxirane, and ethoxyline. Simple epoxides are often referred to as oxides. Thus, the epoxide of ethylene (C2H4) is ethylene oxide (C2H4O). Many compounds have trivial names; for instance, ethylene oxide is called "oxirane". Some names emphasize the presence of the epoxide functional group, as in the compound ''1,2-epoxyheptane'', which can also be called ''1,2-heptene oxide''. A polymer formed from epoxide precursors is called an ''epoxy''. However, few if any of the epoxy groups in ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nervous System
In biology, the nervous system is the complex system, highly complex part of an animal that coordinates its behavior, actions and sense, sensory information by transmitting action potential, signals to and from different parts of its body. The nervous system detects environmental changes that impact the body, then works in tandem with the endocrine system to respond to such events. Nervous tissue first arose in Ediacara biota, wormlike organisms about 550 to 600 million years ago. In Vertebrate, vertebrates, it consists of two main parts, the central nervous system (CNS) and the peripheral nervous system (PNS). The CNS consists of the brain and spinal cord. The PNS consists mainly of nerves, which are enclosed bundles of the long fibers, or axons, that connect the CNS to every other part of the body. Nerves that transmit signals from the brain are called motor nerves (efferent), while those nerves that transmit information from the body to the CNS are called sensory nerves (aff ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gestation
Gestation is the period of development during the carrying of an embryo, and later fetus, inside viviparous animals (the embryo develops within the parent). It is typical for mammals, but also occurs for some non-mammals. Mammals during pregnancy can have one or more gestations at the same time, for example in a multiple birth. The time interval of a gestation is called the '' gestation period''. In obstetrics, '' gestational age'' refers to the time since the onset of the last menses, which on average is fertilization age plus two weeks. Mammals In mammals, pregnancy begins when a zygote (fertilized ovum) implants in the female's uterus and ends once the fetus leaves the uterus during labor or an abortion (whether induced or spontaneous). Humans In humans, pregnancy can be defined clinically, biochemically or biologically. Clinically, pregnancy starts from first day of the mother's last period. Biochemically, pregnancy starts when a woman's human chorionic gonado ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Possible Human Carcinogen
A carcinogen () is any agent that promotes the development of cancer. Carcinogens can include synthetic chemicals, naturally occurring substances, physical agents such as ionizing and non-ionizing radiation, and biologic agents such as viruses and bacteria. Most carcinogens act by creating mutations in DNA that disrupt a cell's normal processes for regulating growth, leading to uncontrolled cellular proliferation. This occurs when the cell's DNA repair processes fail to identify DNA damage allowing the defect to be passed down to daughter cells. The damage accumulates over time. This is typically a multi-step process during which the regulatory mechanisms within the cell are gradually dismantled allowing for unchecked cellular division. The specific mechanisms for carcinogenic activity is unique to each agent and cell type. Carcinogens can be broadly categorized, however, as activation-dependent and activation-independent which relate to the agent's ability to engage direc ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
International Agency For Research On Cancer
The International Agency for Research on Cancer (IARC; ) is an intergovernmental agency forming part of the World Health Organization of the United Nations. Its role is to conduct and coordinate research into the causes of cancer. It also cancer registry, collects and publishes disease surveillance, surveillance data regarding the occurrence of cancer worldwide. Its IARC monographs programme identifies carcinogenic hazards and evaluates environmental carcinogen, causes of cancer in humans. IARC has its own governing council, and in 1965 the first members were West Germany, France, Italy, the United Kingdom, and the United States of America. Today, IARC's membership has grown to 29 countries. History In late February 1963, after he experienced his spouse suffering and dying of cancer, journalist and Mouvement de la Paix, peace activist Yves Poggioli sent a letter to Emmanuel d'Astier de La Vigerie, Emmanuel d'Astier de la Vignerie relating his story, and urging support for ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Breast Milk
Breast milk (sometimes spelled as breastmilk) or mother's milk is milk produced by the mammary glands in the breasts of women. Breast milk is the primary source of nutrition for newborn infants, comprising fats, proteins, carbohydrates, and a varying composition of minerals and vitamins. Breast milk also contains substances that help protect an infant against infection and inflammation, such as Human milk microbiome, symbiotic bacteria and other microorganisms and immunoglobulin A, whilst also contributing to the healthy development of the infant's immune system and gut microbiome. Use and methods of consumption The World Health Organization (WHO) and UNICEF recommend Breastfeeding#Duration and exclusivity, exclusive breastfeeding with breast milk for the first six months of an infant’s life. This period is followed by the incorporation of nutritionally adequate and safe complementary solid foods at six months, a stage when an infant’s nutrient and energy requirements start ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hydrogenation
Hydrogenation is a chemical reaction between molecular hydrogen (H2) and another compound or element, usually in the presence of a catalyst such as nickel, palladium or platinum. The process is commonly employed to redox, reduce or Saturated and unsaturated compounds, saturate organic compounds. Hydrogenation typically constitutes the addition of pairs of hydrogen atoms to a molecule, often an alkene. Catalysts are required for the reaction to be usable; non-catalytic hydrogenation takes place only at very high temperatures. Hydrogenation reduces Double bond, double and Triple bond, triple bonds in hydrocarbons. Process Hydrogenation has three components, the Saturated and unsaturated compounds, unsaturated substrate, the hydrogen (or hydrogen source) and, invariably, a catalyst. The redox, reduction reaction is carried out at different temperatures and pressures depending upon the substrate and the activity of the catalyst. Related or competing reactions The same cataly ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Solubility
In chemistry, solubility is the ability of a chemical substance, substance, the solute, to form a solution (chemistry), solution with another substance, the solvent. Insolubility is the opposite property, the inability of the solute to form such a solution. The extent of the solubility of a substance in a specific solvent is generally measured as the concentration of the solute in a wikt:saturated#Chemistry, saturated solution, one in which no more solute can be dissolved. At this point, the two substances are said to be at the solubility equilibrium. For some solutes and solvents, there may be no such limit, in which case the two substances are said to be "miscibility, miscible in all proportions" (or just "miscible"). The solute can be a solid, a liquid, or a gas, while the solvent is usually solid or liquid. Both may be pure substances, or may themselves be solutions. Gases are always miscible in all proportions, except in very extreme situations,J. de Swaan Arons and G. A. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lipophilic
Lipophilicity (from Greek language, Greek λίπος "fat" and :wikt:φίλος, φίλος "friendly") is the ability of a chemical compound to dissolve in fats, oils, lipids, and non-polar solvents such as hexane or toluene. Such compounds are called lipophilic (translated as "fat-loving" or "fat-liking"). Such non-polar solvents are themselves lipophilic, and the adage "like dissolves like" generally holds true. Thus lipophilic substances tend to dissolve in other lipophilic substances, whereas hydrophilic ("water-loving") substances tend to dissolve in water and other hydrophilic substances. Lipophilicity, hydrophobicity, and non-polarity may describe the same tendency towards participation in the London dispersion force, as the terms are often used interchangeably. However, the terms "lipophilic" and "hydrophobicity, hydrophobic" are not synonymous, as can be seen with silicones and fluorocarbons, which are hydrophobic but not lipophilic. __TOC__ Surfactants Hydrocarbon-based ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
