acute toxicity concerns the adverse effects, which may result from a single exposure or multiple exposures within 24 hours to a substance in toxicity tests. Exposure relates to the oral, dermal or inhalation routes. Assessment of the acute toxic potential of a chemical is necessary to determine the adverse health effects that might occur following accidental or deliberate short-term exposure: the types of toxic effects, their time of onset, duration and severity, the dose-response relationships, and the sex differences in response. The investigated damages can be clinical signs of toxicity, abnormal body weight changes, and/or pathological changes in organs and tissues, which in some cases may result in death.
a drug that fights viruses. It is used to prevent or treat infections you may get when your immune system is not working well. This can happen when cancer treatment weakens the immune system by causing a low white blood cell count.
It is acycloguanosine (ACV), a guanosine analogue antiviral drug, marketed under trade names such as Cyclovir, Herpex, Acivir, Acivirax, Zovirax, and Xovir. One of the most commonly used antiviral drugs, it is primarily used for the treatment of Herpes simplex virus infections, as well as in the treatment of Varicella zoster (chickenpox) and Herpes zoster.
Acyclovir differs from previous nucleoside analogues in containing only a partial nucleoside structure: the sugar ring is replaced with an open-chain structure. It is selectively converted into acyclo-guanosine monophosphate (acyclo-GMP) by viral thymidine kinase, which is far more effective (3000 times) in phosphorylation than cellular thymidine kinase. Subsequently, the monophosphate form is further phosphorylated into the active triphosphate form, acyclo-guanosine triphosphate (acyclo-GTP), by cellular kinases. Acyclo-GTP has approximately 100 times greater affinity for viral than cellular polymerase. As a substrate, acyclo-GTP is incorporated into viral DNA, resulting in premature chain termination. Although acyclovir resembles a nucleotide, it has no 3' end. Therefore, after its incorporation into a growing DNA strand, no further nucleotides can be added to this strand. It has also been shown that viral enzymes cannot remove acyclo-GTP from the chain, which results in inhibition of further activity of DNA polymerase. Acyclo-GTP is fairly rapidly metabolised within the cell, possibly by cellular phosphatases.
In sum, aciclovir can be considered a prodrug: it is administered in an inactive (or less active) form and is metabolised into a more active species after administration.
adaptation is the evolutionary process whereby a population becomes better suited to its habitat. This process takes place over many generations, and is one of the basic phenomena of biology.
The term adaptation may also refer to a feature which is especially important for an organism's survival. Such adaptations are produced in a variable population by the better suited forms reproducing more successfully, that is, by natural selection.
Microorganism, due to their short generation time may succesfully be adapted to new environmental conditions, such as temperature, salinity, nutrient supply, toxic contaminants, etc.
The genom of the microorganisms is very versatile: their adaptive genes, which can be swithched on, when necessary, the frequent mutations and the horizontal gene-transfer between the members of the population and the whole microbial community makes the soil microbes flexible and possible to adapt to the utilisation of new substrates (also soil contaminants) and to become resistant to toxic chemical substances. In the soil biofilms, where microorganism are living strongly realted to each-other, special forms of horizontal gene transfer may exist, and the genes necessary fir survival can be dispersed in the community with the help of mobile genetical elements, such as plasmids, jumping genes, phages, etc.
The adaptive behaviour of the soil microorganisms makes possible to eliminate soil contaminants and prevent Earth from continuously increasing contaminant-concentrations in soils.
adaptive enzymes are inducible enzymes expressed only under conditions in which it is clear of adaptive value, as opposed to a constitutive enzyme which is produced all the time.
Adaptive enzymes are good examples for the efficient functioning of the microbial, plant and animal cells: they do not work (do not synthetize molecules) if not necessary.
To switch-in the production of an adaptive enzyme there is a special mechanism working in the cell: a regulation system with positive or negative feed-back.
The best known adaptive enzyme is the beta-galactosidase, an ezyme which is part of the complex lactase enzyme responsible for the degradation of lactose, the sugar of the milk. This enzyme is produced only in the presence of lactose. Lactose itself is the inductor molecule for the production of the enzyme beta-galactosidase, necessary to split from each other the two sugar-molecules of the disaccharide lactose. The meachanism of enzyme induction is based on the competitive linkage of lactose and the regulatory gene (operator) to the inhibitor molecule.
within the context of REACH, an additive is a compond that has been intentionally added during the manufacturing process to stabilise the substance. Under other legislation additive can have other functions, e.g. pH-regulator or colouring agent.In REACH the term "additive" can also have other meanings outside the context of substance identification, for instance in relation to food or feed additives See REACH, article 2.
the integrated effect of more toxic substances, mixtures of chemical substances, xenobiotica or drogs, which can be quantified as the sum of the effects of the components, contrary to not additive effects, such as antagonism or sinergism.
an amendment-enhanced bioremediation technology for the treatment of POPs involves the creation of sequential anoxic and oxic conditions. The treatment process involves the following:
1. Addition of solid phase DARAMEND® organic soil amendment of specific particle size distribution and nutrient profile, zero valent iron, and water to produce anoxic conditions.
2. Periodic tilling of the soil to promote oxic conditions.
3. Repetition of the anoxic-oxic cycle until the desired cleanup goals are achieved.
The addition of DARAMEND® organic amendment, zero valent iron, and water stimulates the biological depletion of oxygen, generating strong reducing anoxic conditions within the soil matrix. The diffusion of replacement oxygen into the soil matrix is prevented by near saturation of the soil pores with water. The depletion of oxygen creates a low redox potential, which promotes dechlorination of organochlorine compounds. A cover may be used to control the moisture content, increase the temperature of the soil matrix and eliminate runon/run off.
The soil matrix consisting of contaminated soil and the amendments is left undisturbed for the duration of the anoxic phase of treatment cycle typically 1-2 weeks. In the oxic phase of each cycle, periodic tilling of the soil increases diffusion of oxygen to microsites and distribution of irrigation water in the soil. The dechlorination products formed during the anoxic degradation process are subsequently removed trough aerobic oxic biodegradation processes, initiated by the passive air drying and tilling of the soil to promote aerobic conditions.
Addition of DARAMEND® and the anoxic-oxic cycle continues until the desired cleanup goals are achieved. The frequency of irrigation is determined by weekly monitoring of soil moisture conditions. Soil moisture is maintained within a specific range below its water holding capacity. Maintenance of soil moisture content within a specified range facilitates rapid growth of an active microbial population and prevents the generation of leachate. The amount of DARAMEND® added in the second and subsequent treatment cycles is generally less than the amount added during the first cycle.
The additive enhanced bioremediation was successfully applied for toxaphene and DDT contaminated soil and sediment.
within the context of REACH, an additive is a compound that has been intentionally added during the manufacturing process to stabilise the substance. Under other legislation additive can have other functions, e.g. pH-regulator or colouring agent.
In REACH the term "additive" can also have other meanings outside the context of substance identification, for instance in relation to food or feed additives. (See REACH, article 2)
(Source: REACH Glossary)
adenocarcinoma is a type of cancer that begins in cells that line the inside of organs. These organs make substances like hormones or milk. Most breast cancers are of this type. They begin in cells that make milk or in the cells that drain the breast milk.
See also breast cancer.
adjuvant is substance, which is added to a formulated pesticide product to act as a wetting or spreading agent, sticker, penetrant, or emulsifier in order to enhance the physical characteristics of the product.
European Agreement concerning the International Carriage of Dangerous Goods by Inland Waterways.
The European Agreement concerning the International Carriage of Dangerous Goods by Inland Waterways (ADN) was done at Geneva on 26 May 2000 on the occassion of a Diplomatic Conference held under the joint auspices of the United Nations Economic Commission for Europe (UNECE) and the Central Commission for the Navigation of the Rhine (CCNR). It entered into force on 29 February 2008.
ADN consists of a main legal text (the Agreement itself) and annexed Regulations and aims at:
(i) ensuring a high level of safety of international carriage of dangerous goods by inland waterways;
(ii) contributing effectively to the protection of the environment, by preventing any pollution resulting from accidents or incidents during such carriage; and
(iii) facilitating transport operations and promoting international trade in dangerous goods.
ADN 2009 is a consolidated version which takes account of these updates and is applicable as from 28 February 2009.
adrenaline, also called epinephrine, is a hormone and neurotransmitter. In stress situation it increases heart rate, contracts blood vessels and dilates air passages and participates in the response of the sympathetic nervous system. Chemically it is a phenyl-ethyl-amine, a special monoamine produced only by the adrenal glands from phenylalanine and tyrosine.
a drug that kills cancer cells by stopping their growth. It can also make it hard for cancer cells to fix damage. It is a type of chemotherapy.
Brand name: Adriamycin
Chemical name: Doxorubicin
Class: anthracycline chemotherapy.
Doxil, daunorubicin, Ellence, and mitoxantrone are other anthracyclines.
How it works: Anthracyclines kill cancer cells by damaging their genes and interfering with their reproduction.
Uses: adriamycin usually is given in combination with other chemotherapy medicines. It's typically used: after surgery to reduce the risk of early-stage breast cancer coming back before surgery to shrink large advanced-stage breast cancer tumors to treat advanced-stage breast cancer
How it's given: adriamycin is given intravenously.
Additional information: Adriamycin can have a toxic effect on the heart. You should be tested for heart problems before starting to take Adriamycin and should be continuously monitored for developing problems during treatment.
- low white blood cell count
- increased risk of bleeding from low platelet count
- appetite changes
- nail changes
- hair loss
- mouth sores
- heart problems
- hand-foot syndrome
- irregular periods -- this can include temporary cessation (usually resume after medication is completed) or permanent cessation of menstrual periods depending on your age and other factors
See also: http://www.nlm.nih.gov/medlineplus/druginfo/meds/a682221.html
ADSL= Asymmetric DSL
adsorbent is an adsorptive material, which is able to adsorb other materials on its specific surface.Adsorption is a consequence of surface energy. Atoms on the surface of the adsorbent are not wholly surrounded by other adsorbent atoms and therefore can attract adsorbates. The exact nature of the bonding depends on the details of the species involved, but the adsorption process is generally classified as physical adsorption by weak van der Waals forces, or chemical adsorption by ionic or covalent bonding.
Most weel known adsorbents are activated carbon, activated zeolites, bentonites, aluminium-oxides, magnesium-oxides, silica gels, ceramics, polimers, nanoadsorbers. After use most of the adsorbents can be regenerated and reuse.
adsorber is a device filled with absorbent, which is a solid material, such as activated carbon, that has a high surface area and is used to capture a gas or liquid.
adsorption is the accumulation of atoms or molecules on the surface of a material. This process creates a film of the absorbate the molecules or atoms being accumulated on the adsorbent's surface. It is different from absorption, in which a substance diffuses into a liquid or solid to form a solution. The term sorption encompasses both processes.
Adsorption is often confused with absorption, where the substance being collected or removed actually penetrates into the other substance
Adsorption is a consequence of surface energy: in a bulk material, all the bonding requirements of the constituent atoms of the material are filled by other atoms in the material. However, atoms on the surface of the adsorbent are not wholly surrounded by other adsorbent atoms and therefore can attract adsorbates. The exact nature of the bonding depends on the details of the species involved, but the adsorption process is generally classified as a physical process in which weak secondary boundings with van der Waals forces plays role, or a chemisorption, in which covalent bonding is characteristic.
Adsorption is widely used in environmental technologies and soil remediation for soil air or soil gas treatment, for the treatment of the desorbed contaminants from solid soil by thermal desorption technology, for the recovery of valuable gases or vapours, for ground water, surface water, drainages water and leachate treatment, for the purification of extracts, etc.
to transport or carry. For example particulate matter is transported in air by wind, liquid form matter is flowing and contaminants are transported by this flow, etc.
change in morphology, physiology, growth, development or lifespan of an organism which results in impairment of its functional capacity or impairment of its capacity to compensate for additional stress or increased susceptibility to the harmful effects of other environmental influences. (Source: REACH Glossary)
a change in body function or cell structure that might lead to disease or health problems.
aeration of soil means the amount of air-filled pores in the soil, expressed as the volume difference between total porosity and actual soil moisture. Optimum soil aeration is 30% but strongly depends on the structure and packing state of soil particles; 15–20% is normally satisfactory for the growth of grasses and cereals; below 10% is not good for plant growth.
Aerobic and facultative anaerobic microorganisms in the soil may intesively use oxigene and produce CO2 when biodegradable organic soil-contaminants are present in high concentration. If oxygen have been consumed, the redoxpotential decreases in soil, and slower facultative anaerobs start to dominate: the biodegradation of contaminants slows down.
A biodegradation based soil remediation technology can be intensified by soil aeration, increasing the redoxpotential in the soil and activating aerobic degrading microorganisms. This process is called bioventing.
aerobic conditions or processes are those, which require oxigen. In environmental and biological systems biologically available oxigen can be derived from the atmospher in the form of atmospheric air, from the water in the form of water-dissolved oxigen for aquatic-ecosystem, or in the form of soil-air for the soil living organisms. If the oxigen is not enough or not available, the conditions are anoxic. If no oxigen is present at all, we speak about anaerobic conditions.
The biological activity in the presence of oxigen is called: aerobiosis, under anaerobic conditions: anaerobiosis.
acoustic noise caused by turbulent airflow over the surface of a body.
converting a bare or agricultural space by planting trees and plants; reforestation involves replanting trees on areas that have been cut or destroyed by fire.
an aggregate is a collection of items that are gathered together to form a total quantity.
In environmental sciences we use the term "aggregate" for those crystals, atoms, ions, molecules or living cells, which are not connected to each other with physical, chemical or biological forces or bondage, but are just gathered together.
cancer cells that are fast-growing and have a tendency to spread beyond the area where they started.
the contamination of the atmosphere by any toxic or radioactive gases and particulate matter as a result of human activity.
COUNCIL DIRECTIVE 84/360/EEC of 28 June 1984 on the combating of air pollution from industrial plants definition is: air pollution is the introduction by man, directly or indirectly, of substances or energy into the air resulting in deleterious effects of such a nature as to endanger human health, harm living resources and ecosystems and material property and impair or interfere with amenities and other legitimate uses of the environment.
Source: Council Directive 84/360/EEC of 28 June 1984 on the combating of air pollution from industrial plants, http://eur-lex.europa.eu/LexUriServ/LexUriServ.do?uri=CELEX:31984L0360:EN:HTML
air pressure is the force exerted by the weight of a column of air above a particular region. Air pressure is measured in pounds per square inch, inches of mercury, or millibars.
level of pollution, and lengths of exposure, above which adverse human health and welfare effects may occur. A prescribed level of atmospheric pollution allowed for a certain compound during a specific time in a specific geographical area. Standards are set by regulating bodies, or agencies.
air sparging involves the injection of air or oxygen through a contaminated aquifer. Injected air traverses horizontally and vertically in channels through the soil column, creating an underground stripper that removes volatile and semivolatile organic contaminants by volatilization. The injected air helps to flush the contaminants into the unsaturated zone. SVE usually is implemented in conjunction with air sparging to remove the generated vapor-phase contamination from the vadose zone. Oxygen added to the contaminated groundwater and vadose-zone soils also can enhance biodegradation of contaminants below and above the water table.
Source: EPA, ClU-In − http://www.clu-in.org/techfocus/default.focus/sec/Air_Sparging/cat/Overview/
air toxicology measures indoor and outdoor air quality and compares to quality criteria.
noise caused by the movement of large volumes of air and the use of high-pressure air.