Instruct: Given a question, retrieve passages that can help answer the question.
Query: Where are polycyclic aromatic hydrocarbons found?
Many of the polycyclic aromatic hydrocarbons known to be tumorigenic or mutagenic are found in atmospheric aerosols, which is connected to the thermal rearrangement of polycyclic aromatic hydrocarbons in fast soot formation during combustion.
Organophosphate is the general name for esters of phosphoric acid and is one of the organophosphorus compounds. They can be found as part of insecticides, herbicides, and nerve gases, amongst others. Some less-toxic organophosphates can be used as solvents, plasticizers, and EP additives. The use of organophosphates accounts for approximately 38% of all pesticide use globally.
In October 2014, Houston-based oil field services company Baker Hughes was reported to have produced 1,000 pink drill bits to raise breast cancer awareness. The land drill bits are used to break up geologic formations in oil patches for hydraulic fracturing. These ties have been criticized, because of the more than 700 chemicals used in fracking more than one third are endocrine disruptors and at least one quarter increase the risk of cancer.
Internal combustion engines such as reciprocating internal combustion engines produce air pollution emissions, due to incomplete combustion of carbonaceous fuel. The main derivatives of the process are carbon dioxide , water and some soot—also called particulate matter (PM). The effects of inhaling particulate matter have been studied in humans and animals and include asthma, lung cancer, cardiovascular issues, and premature death. There are, however, some additional products of the combustion process that include nitrogen oxides and sulfur and some uncombusted hydrocarbons, depending on the operating conditions and the fuel-air ratio.
The patch is not easily seen from the sky, because the plastic is dispersed over a large area. Researchers from The Ocean Cleanup project claimed that the patch covers 1.6 million square kilometers. The plastic concentration is estimated to be up to 100 kilograms per square kilometer in the center, going down to 10 kilograms per square kilometer in the outer parts of the patch. An estimated 80,000 metric tons of plastic inhabit the patch, totaling 1.8 trillion pieces. 92% of the mass in the patch comes from objects larger than 0.5 centimeters.
The Toxic 100 Air polluters index from the University of Massachusetts lists Precision Castparts as the number one air polluter in the U.S. in the August 2013 edition, which the company called a flawed study.
Natural biodegradable polymers are formed in nature during growth cycles of all organisms. When searching for natural fibers to replace synthetic materials in athletic shoes, the major natural biodegradable polymer that offers the most potential are polysaccharides. Starch is a polysaccharide that is useful because it readily degrades into harmless products when placed in contact with soil microorganisms.
Organophosphate pesticides are one of the top causes of poisoning worldwide, with an annual incidence of poisonings among agricultural workers varying from 3-10% per country.
Raw natural gas consists primarily of methane (CH), the shortest and lightest hydrocarbon molecule, as well as various amounts of heavier hydrocarbon gases such as ethane (CH), propane (CH), normal butane ("n"-CH), isobutane ("i"-CH), pentanes and even higher-molecular-mass hydrocarbons. The raw gas also contains various amounts of acid gases such as carbon dioxide (CO), hydrogen sulfide (HS) and mercaptans such as methanethiol (CHSH) and ethanethiol (CHSH).
People have been using natural organic polymers for centuries in the form of waxes and shellac, which is classified as a thermoplastic polymer. A plant polymer named cellulose provided the tensile strength for natural fibers and ropes, and by the early 19th century natural rubber was in widespread use. Polymers are the raw materials (the resins) used to make what are commonly called plastics. Plastics are the final product, created after one or more polymers or additives have been added to a resin during processing, which is then shaped into a final form. Polymers that have been around, and that are in current widespread use, include carbon-based polyethylene, polypropylene, polyvinyl chloride, polystyrene, nylons, polyesters, acrylics, polyurethane, and polycarbonates, and silicon-based silicones. Plastics are generally classified as "commodity", "specialty" and "engineering" plastics.
Between April 2000 and April 2001, the APCD, the U.S. Environmental Protection Agency, the Kentucky Division for Air Quality, and the University of Louisville worked with the WJCCTF to conduct an air monitoring study of a large number of toxic air pollutants at twelve sites in western Louisville and Jefferson County. The purpose of the study was to determine if residents of the area were being exposed to airborne concentrations of toxic air pollutants that may pose unacceptable risks to human health. Since the end of that one-year study, the university and WJCCTF have continued to sample volatile organic compounds at some of the sites.
In any part of the world that uses organophosphates, "C. megacephala" could prove to be beneficial. Organophosphate compounds are used in agriculture and are highly toxic. Organophosphate poisoning often causes death, and in many cases, by evaluating the body tissue and fluids, the toxin can be identified as the source of the poisoning. However, it is somewhat difficult to evaluate the body tissue in a body that is exceedingly decomposed. Nevertheless, a medical examiner in Hawaii worked on a case in which poisoning by malathion, an organophosphate insecticide, was thought to be the cause of death. The victim’s stomach contents and body fat were examined and found to have contained malathion. The fly larvae of "Chrysomya megacephala" and "Chrysomya rufifacies" were also present at the scene on the body and were tested for malathion. Both of these species did contain malathion, but there had been no previous record of organophosphates in their larvae. Studying larvae from decomposed remains may provide an effective method of determining the presence of these toxins in a body that is extremely decayed.
Some familiar household synthetic polymers include: Nylons in textiles and fabrics, Teflon in non-stick pans, Bakelite for electrical switches, polyvinyl chloride (PVC) in pipes, etc. The common PET bottles are made of a synthetic polymer, polyethylene terephthalate. The plastic kits and covers are mostly made of synthetic polymers like polythene and tires are manufactured from Buna rubbers. However, due to the environmental issues created by these synthetic polymers which are mostly non-biodegradable and often synthesized from petroleum, alternatives like bioplastics are also being considered. They are however expensive when compared to the synthetic polymers.The eight most common types of synthetic organic polymers, which are commonly found in households are:
In chemistry, particularly in biochemistry, a fatty acid is a carboxylic acid with a long aliphatic chain, which is either saturated or unsaturated. Most naturally occurring fatty acids have an unbranched chain of an even number of carbon atoms, from 4 to 28. Fatty acids are usually not found in organisms, but instead as three main classes of esters: triglycerides, phospholipids, and cholesterol esters. In any of these forms, fatty acids are both important dietary sources of fuel for animals and they are important structural components for cells.
People of lower socioeconomic status are found to be more vulnerable to air pollutant, PM 2.5, due to their location. PM 2.5 is an air pollutant, arising from the blend of power plants, refineries, and diesel engines, among other sources, and this particle penetrates the lungs. Communities of low socioeconomic statuses are frequently concentrated in areas near highways, busy roads, and refineries. Therefore, limiting one's exposure to air pollution in an impoverished environment is nearly impossible. Communities of low socioeconomic status face an unequal access to environmental health services and resources.
Group C
Group D
Pollution in California relates to the degree of pollution in the air, water, and land of the state of California. Pollution is defined as the addition of any substance (solid, liquid, or gas) or any form of energy (such as heat, sound, or radioactivity) to the environment at a faster rate than it can be dispersed, diluted, decomposed, recycled, or stored in some harmless form. The combination of three main factors are the cause of notable unhealthy levels of air pollution in California: the activities of over 39 million people, a mountainous terrain that traps pollution, and a warm climate that helps form ozone and other pollutants. Eight of the ten cities in the US with the highest year-round concentration of particulate matter between 2013 and 2015 were in California, and seven out of the ten cities in the US with the worst ozone pollution were also in California. Studies show that pollutants prevalent in California are linked to several health issues, including asthma, lung cancer, birth complications, and premature death. In 2016, Bakersfield, California recorded the highest level of airborne pollutants of any city in the United States.
Xenoestrogens are a type of xenohormone that imitates estrogen. They can be either synthetic or natural chemical compounds. Synthetic xenoestrogens include some widely used industrial compounds, such as PCBs, BPA, and phthalates, which have estrogenic effects on a living organism even though they differ chemically from the estrogenic substances produced internally by the endocrine system of any organism. Natural xenoestrogens include phytoestrogens which are plant-derived xenoestrogens. Because the primary route of exposure to these compounds is by consumption of phytoestrogenic plants, they are sometimes called "dietary estrogens". Mycoestrogens, estrogenic substances from fungi, are another type of xenoestrogen that are also considered mycotoxins.
Oil shale is an organic-rich fine-grained sedimentary rock containing kerogen (a solid mixture of organic chemical compounds) from which liquid hydrocarbons can be produced, called shale oil (not to be confused with tight oil—crude oil occurring naturally in shales). Shale oil is a substitute for conventional crude oil; however, extracting shale oil from oil shale is more costly than the production of conventional crude oil both financially and in terms of its environmental impact. Deposits of oil shale occur around the world, including major deposits in the United States. A 2016 estimate of global deposits set the total world resources of oil shale equivalent of of oil in place.
The chemist Hermann Staudinger first proposed that polymers consisted of long chains of atoms held together by covalent bonds, which he called macromolecules. His work expanded the chemical understanding of polymers and was followed by an expansion of the field of polymer chemistry during which such polymeric materials as neoprene, nylon and polyester were invented. Before Staudinger, polymers were thought to be clusters of small molecules (colloids), without definite molecular weights, held together by an unknown force. Staudinger received the Nobel Prize in Chemistry in 1953. Wallace Carothers invented the first synthetic rubber called neoprene in 1931, the first polyester, and went on to invent nylon, a true silk replacement, in 1935. Paul Flory was awarded the Nobel Prize in Chemistry in 1974 for his work on polymer random coil configurations in solution in the 1950s. Stephanie Kwolek developed an aramid, or aromatic nylon named Kevlar, patented in 1966. Karl Ziegler and Giulio Natta received a Nobel Prize for their discovery of catalysts for the polymerization of alkenes. Alan J. Heeger, Alan MacDiarmid, and Hideki Shirakawa were awarded the 2000 Nobel Prize in Chemistry for the development of polyacetylene and related conductive polymers. Polyacetylene itself did not find practical applications, but organic light-emitting diodes (OLEDs) emerged as one application of conducting polymers.
Polycyclic aromatic hydrocarbons (PAHs, also polyaromatic hydrocarbons or polynuclear aromatic hydrocarbons) are hydrocarbons—organic compounds containing only carbon and hydrogen—that are composed of multiple aromatic rings (organic rings in which the electrons are delocalized). The simplest such chemicals are naphthalene, having two aromatic rings, and the three-ring compounds anthracene and phenanthrene.
Priority polycyclic aromatic hydrocarbons identified by the US EPA, the US Agency for Toxic Substances and Disease Registry (ATSDR), and the European Food Safety Authority (EFSA) due to their carcinogenicity or genotoxicity and/or ability to be monitored are the following:
Erich Clar (August 23, 1902 – March 27, 1987) was an organic chemist who studied polycyclic aromatic hydrocarbon chemistry. He is considered as the father of that field. He authored the two-volume "Polycyclic Hydrocarbons", which described the syntheses, properties, and UV-visible absorption spectra of hundreds of PAHs. He created the Sextet Theory, now eponymously called "Clar's rule", to describe the behavior of PAH isomers. This was described in his book "The Aromatic Sextet". He was awarded the August Kekulé Medal by the Chemical Society of the GDR in 1965, the highest award given by that society to foreign scientists, and the first Polycyclic Aromatic Hydrocarbon Research Award of the International Symposium on Polynuclear Aromatic Hydrocarbons in 1987.
Spiral galaxy NGC 5529 has been found to have amounts of PAHs.