European Chemicals Agency
The European Chemicals Agency is an agency of the European Union which manages the technical and administrative aspects of the implementation of the European Union regulation called Registration, Evaluation and Restriction of Chemicals. ECHA is the driving force among regulatory authorities in implementing the EU's chemicals legislation. ECHA helps companies to comply with the legislation, advances the safe use of chemicals, provides information on chemicals and addresses chemicals of concern, it is located in Finland. The agency headed by Executive Director Bjorn Hansen, started working on 1 June 2007; the REACH Regulation requires companies to provide information on the hazards and safe use of chemical substances that they manufacture or import. Companies register this information with ECHA and it is freely available on their website. So far, thousands of the most hazardous and the most used substances have been registered; the information is technical but gives detail on the impact of each chemical on people and the environment.
This gives European consumers the right to ask retailers whether the goods they buy contain dangerous substances. The Classification and Packaging Regulation introduces a globally harmonised system for classifying and labelling chemicals into the EU; this worldwide system makes it easier for workers and consumers to know the effects of chemicals and how to use products safely because the labels on products are now the same throughout the world. Companies need to notify ECHA of the labelling of their chemicals. So far, ECHA has received over 5 million notifications for more than 100 000 substances; the information is available on their website. Consumers can check chemicals in the products. Biocidal products include, for example, insect disinfectants used in hospitals; the Biocidal Products Regulation ensures that there is enough information about these products so that consumers can use them safely. ECHA is responsible for implementing the regulation; the law on Prior Informed Consent sets guidelines for the import of hazardous chemicals.
Through this mechanism, countries due to receive hazardous chemicals are informed in advance and have the possibility of rejecting their import. Substances that may have serious effects on human health and the environment are identified as Substances of Very High Concern 1; these are substances which cause cancer, mutation or are toxic to reproduction as well as substances which persist in the body or the environment and do not break down. Other substances considered. Companies manufacturing or importing articles containing these substances in a concentration above 0,1% weight of the article, have legal obligations, they are required to inform users about the presence of the substance and therefore how to use it safely. Consumers have the right to ask the retailer whether these substances are present in the products they buy. Once a substance has been identified in the EU as being of high concern, it will be added to a list; this list is available on ECHA's website and shows consumers and industry which chemicals are identified as SVHCs.
Substances placed on the Candidate List can move to another list. This means that, after a given date, companies will not be allowed to place the substance on the market or to use it, unless they have been given prior authorisation to do so by ECHA. One of the main aims of this listing process is to phase out SVHCs where possible. In its 2018 substance evaluation progress report, ECHA said chemical companies failed to provide “important safety information” in nearly three quarters of cases checked that year. "The numbers show a similar picture to previous years" the report said. The agency noted that member states need to develop risk management measures to control unsafe commercial use of chemicals in 71% of the substances checked. Executive Director Bjorn Hansen called non-compliance with REACH a "worry". Industry group CEFIC acknowledged the problem; the European Environmental Bureau called for faster enforcement to minimise chemical exposure. European Chemicals Bureau Official website
Recreational drug use
Recreational drug use is the use of a psychoactive drug to induce an altered state of consciousness for pleasure, by modifying the perceptions and emotions of the user. When a psychoactive drug enters the user's body, it induces an intoxicating effect. Recreational drugs are in three categories: depressants. Many people use prescribed and illegal opioids along with opiates and benzodiazepines. In popular practice, recreational drug use is a tolerated social behaviour, rather than perceived as the serious medical condition of self-medication. However, heavy use of some drugs is stigmatized. Recreational drugs include alcohol. What controlled substances are considered illegal drugs varies by country, but includes methamphetamines, cocaine, LSD, psilocybin mushrooms, MDMA and club drugs. In 2015, it was estimated that about 5% of people aged 15 to 65 had used illegal drugs at least once. Many researchers have explored the etiology of recreational drug use; some of the most common theories are: genetics, personality type, psychological problems, self-medication, age, instant gratification, basic human need, rebelliousness, a sense of belonging to a group and attachment issues, history of trauma, failure at school or work, socioeconomic stressors, peer pressure, juvenile delinquency, historical factors, or sociocultural influences.
There has not been agreement around any one single cause. Instead, experts tend to apply the biopsychosocial model. Any number of these factors are to influence an individual's drug use as they are not mutually exclusive. Regardless of genetics, mental health or traumatic experiences, social factors play a large role in exposure to and availability of certain types of drugs and patterns of drug use. According to addiction researcher Martin A. Plant, many people go through a period of self-redefinition before initiating recreational drug use, they tend to view using drugs as part of a general lifestyle that involves belonging to a subculture that they associate with heightened status and the challenging of social norms. Plant says, “From the user's point of view there are many positive reasons to become part of the milieu of drug taking; the reasons for drug use appear to have as much to do with needs for friendship and status as they do with unhappiness or poverty. Becoming a drug taker, to many people, is a positive affirmation rather than a negative experience.”
Anthropological research has suggested that humans "may have evolved to counter-exploit plant neurotoxins". The ability to use botanical chemicals to serve the function of endogenous neurotransmitters may have improved survival rates, conferring an evolutionary advantage. A restrictive prehistoric diet may have emphasised the apparent benefit of consuming psychoactive drugs, which had themselves evolved to imitate neurotransmitters. Chemical–ecological adaptations, the genetics of hepatic enzymes cytochrome P450, have led researchers to propose that "humans have shared a co-evolutionary relationship with psychotropic plant substances, millions of years old." Severity and type of risks that come with recreational drug use vary with the drug in question and the amount being used. There are many factors in the environment and within the user that interact with each drug differently. Overall, some studies suggest. However, studies which focus on a moderate level of alcohol consumption have concluded that there can be substantial health benefits from its use, such as decreased risk of cardiac disease and cognitive decline.
This claim has been disputed. Researcher David Nutt stated that these studies showing benefits for "moderate" alcohol consumption lacked control for the variable of what the subjects were drinking, beforehand. Experts in the UK have suggested that some drugs that may be causing less harm, to fewer users, include cannabis, psilocybin mushrooms, LSD, ecstasy; these drugs are not without their own particular risks. The concept of "responsible drug use" is that a person can use drugs recreationally or otherwise with reduced or eliminated risk of negatively affecting other aspects of one's life or other people's lives. Advocates of this philosophy point to the many well-known artists and intellectuals who have used drugs, experimentally or otherwise, with few detrimental effects on their lives. Responsible drug use becomes problematic only when the use of the substance interferes with the user's daily life. Responsible drug use advocates that users should not take drugs at the same time as activities such as driving, operating machinery, or other activities that are unsafe without a sober state.
Responsible drug use is emphasized as a primary prevention technique in harm-reduction drug policies. Harm-reduction policies were popularized in the late 1980s, although they began in the 1970s counter-culture, when cartoons explaining responsible drug use and the co
The density, or more the volumetric mass density, of a substance is its mass per unit volume. The symbol most used for density is ρ, although the Latin letter D can be used. Mathematically, density is defined as mass divided by volume: ρ = m V where ρ is the density, m is the mass, V is the volume. In some cases, density is loosely defined as its weight per unit volume, although this is scientifically inaccurate – this quantity is more called specific weight. For a pure substance the density has the same numerical value as its mass concentration. Different materials have different densities, density may be relevant to buoyancy and packaging. Osmium and iridium are the densest known elements at standard conditions for temperature and pressure but certain chemical compounds may be denser. To simplify comparisons of density across different systems of units, it is sometimes replaced by the dimensionless quantity "relative density" or "specific gravity", i.e. the ratio of the density of the material to that of a standard material water.
Thus a relative density less than one means. The density of a material varies with pressure; this variation is small for solids and liquids but much greater for gases. Increasing the pressure on an object decreases the volume of the object and thus increases its density. Increasing the temperature of a substance decreases its density by increasing its volume. In most materials, heating the bottom of a fluid results in convection of the heat from the bottom to the top, due to the decrease in the density of the heated fluid; this causes it to rise relative to more dense unheated material. The reciprocal of the density of a substance is called its specific volume, a term sometimes used in thermodynamics. Density is an intensive property in that increasing the amount of a substance does not increase its density. In a well-known but apocryphal tale, Archimedes was given the task of determining whether King Hiero's goldsmith was embezzling gold during the manufacture of a golden wreath dedicated to the gods and replacing it with another, cheaper alloy.
Archimedes knew that the irregularly shaped wreath could be crushed into a cube whose volume could be calculated and compared with the mass. Baffled, Archimedes is said to have taken an immersion bath and observed from the rise of the water upon entering that he could calculate the volume of the gold wreath through the displacement of the water. Upon this discovery, he leapt from his bath and ran naked through the streets shouting, "Eureka! Eureka!". As a result, the term "eureka" entered common parlance and is used today to indicate a moment of enlightenment; the story first appeared in written form in Vitruvius' books of architecture, two centuries after it took place. Some scholars have doubted the accuracy of this tale, saying among other things that the method would have required precise measurements that would have been difficult to make at the time. From the equation for density, mass density has units of mass divided by volume; as there are many units of mass and volume covering many different magnitudes there are a large number of units for mass density in use.
The SI unit of kilogram per cubic metre and the cgs unit of gram per cubic centimetre are the most used units for density. One g/cm3 is equal to one thousand kg/m3. One cubic centimetre is equal to one millilitre. In industry, other larger or smaller units of mass and or volume are more practical and US customary units may be used. See below for a list of some of the most common units of density. A number of techniques as well as standards exist for the measurement of density of materials; such techniques include the use of a hydrometer, Hydrostatic balance, immersed body method, air comparison pycnometer, oscillating densitometer, as well as pour and tap. However, each individual method or technique measures different types of density, therefore it is necessary to have an understanding of the type of density being measured as well as the type of material in question; the density at all points of a homogeneous object equals its total mass divided by its total volume. The mass is measured with a scale or balance.
To determine the density of a liquid or a gas, a hydrometer, a dasymeter or a Coriolis flow meter may be used, respectively. Hydrostatic weighing uses the displacement of water due to a submerged object to determine the density of the object. If the body is not homogeneous its density varies between different regions of the object. In that case the density around any given location is determined by calculating the density of a small volume around that location. In the limit of an infinitesimal volume the density of an inhomogeneous object at a point becomes: ρ = d m / d V, where d V is an elementary volume at position r; the mass of the body t
An odor, or odour, is caused by one or more volatilized chemical compounds that are found in low concentrations that humans and animals can perceive by their sense of smell. An odor is called a "smell" or a "scent", which can refer to either a pleasant or an unpleasant odor. While "scent" can refer to pleasant and unpleasant odors, the terms "scent", "aroma", "fragrance" are reserved for pleasant-smelling odors and are used in the food and cosmetic industry to describe floral scents or to refer to perfumes. In the United Kingdom, "odour" refers to scents in general. An unpleasant odor can be described as "reeking" or called a "malodor", "stench", "pong", or "stink"; the perception of odors, or sense of smell, is mediated by the olfactory nerve. The olfactory receptor cells are neurons present in the olfactory epithelium, a small patch of tissue at the back of the nasal cavity. There are millions of olfactory receptor neurons; each neuron has cilia in direct contact with the air. Odorous molecules bind to receptor proteins extending from cilia and act as a chemical stimulus, initiating electric signals that travel along the olfactory nerve's axons to the brain.
When an electrical signal reaches a threshold, the neuron fires, which sends a signal traveling along the axon to the olfactory bulb, a part of the limbic system of the brain. Interpretation of the smell begins there, relating the smell to past experiences and in relation to the substance inhaled; the olfactory bulb acts as a relay station connecting the nose to the olfactory cortex in the brain. Olfactory information is further processed and forwarded to the central nervous system, which controls emotions and behavior as well as basic thought processes. Odor sensation depends on the concentration available to the olfactory receptors. A single odorant is recognized by many receptors. Different odorants are recognized by combinations of receptors; the patterns of neuron signals help to identify the smell. The olfactory system does not interpret a single compound, but instead the whole odorous mix; this does not correspond to the intensity of any single constituent. Most odors consists of organic compounds, although some simple compounds not containing carbon, such as hydrogen sulfide and ammonia, are odorants.
The perception of an odor effect is a two-step process. First, there is the physiological part; this is the detection of stimuli by receptors in the nose. The stimuli are recognized by the region of the human brain; because of this, an objective and analytical measure of odor is impossible. While odor feelings are personal perceptions, individual reactions are related, they relate to things such as gender, state of health, personal history. The ability to identify odor varies among decreases with age. Studies show there are sex differences in odor discrimination, women outperform men. Pregnant women have increased smell sensitivity, sometimes resulting in abnormal taste and smell perceptions, leading to food cravings or aversions; the ability to taste decreases with age as the sense of smell tends to dominate the sense of taste. Chronic smell problems are reported in small numbers for those in their mid-twenties, with numbers increasing with overall sensitivity beginning to decline in the second decade of life, deteriorating appreciably as age increases once over 70 years of age.
For most untrained people, the process of smelling gives little information concerning the specific ingredients of an odor. Their smell perception offers information related to the emotional impact. Experienced people, such as flavorists and perfumers, can pick out individual chemicals in complex mixtures through smell alone. Odor perception is a primal sense; the sense of smell enables pleasure, can subconsciously warn of danger, help locate mates, find food, or detect predators. Humans have a good sense of smell, correlated to an evolutionary decline in sense of smell. A human's sense of smell is just as good as many animals and can distinguish a diversity of odors—approximately 10,000 scents. Studies reported. Odors that a person is used to, such as their own body odor, are less noticeable than uncommon odors; this is due to habituation. After continuous odor exposure, the sense of smell is fatigued, but recovers if the stimulus is removed for a time. Odors can change due to environmental conditions: for example, odors tend to be more distinguishable in cool dry air.
Habituation affects the ability to distinguish odors after continuous exposure. The sensitivity and ability to discriminate odors diminishes with exposure, the brain tends to ignore continuous stimulus and focus on differences and changes in a particular sensation; when odorants are mixed, a habitual odorant is blocked. This depends on the strength of the odorants in the mixture, which can change the perception and processing of an odor; this process helps classify similar odors as well as adjust sensitivity to differences in complex stimuli. The primary gene sequences for thousands of olfactory receptors are known for the genomes of more than a dozen organisms, they are seven-helix-turn transmembrane proteins. But there are no known structures for any olfactory receptor. There is a conserved sequence in three quarters of all ORs; this is a tripodal metal-ion binding site, and
Euphoria is the experience of pleasure or excitement and intense feelings of well-being and happiness. Certain natural rewards and social activities, such as aerobic exercise, listening to or making music, dancing, can induce a state of euphoria. Euphoria is a symptom of certain neurological or neuropsychiatric disorders, such as mania. Romantic love and components of the human sexual response cycle are associated with the induction of euphoria. Certain drugs, many of which are addictive, can cause euphoria, which at least motivates their recreational use. Hedonic hotspots – i.e. the pleasure centers of the brain – are functionally linked. Activation of one hotspot results in the recruitment of the others. Inhibition of one hotspot results in the blunting of the effects of activating another hotspot. Therefore, the simultaneous activation of every hedonic hotspot within the reward system is believed to be necessary for generating the sensation of an intense euphoria; the word "euphoria" is derived from the Ancient Greek terms εὐφορία: εὖ eu meaning "well" and φέρω pherō meaning "to bear".
It is semantically opposite to dysphoria. A 1706 English dictionary defines euphoria as "the well bearing of the Operation of a Medicine, i.e. when the patient finds himself eas'd or reliev'd by it". In the 1860s, the English physician Thomas Laycock described euphoria as the feeling of bodily well-being and hopefulness. Sigmund Freud's 1884 monograph Über Coca described consumption of cocaine producing "the normal euphoria of a healthy person", while about 1890 the German neuropsychiatrist Carl Wernicke lectured about the "abnormal euphoria" in patients with mania. A 1903 article in The Boston Daily Globe refers to euphoria as "pleasant excitement" and "the sense of ease and well-being". In 1920 Popular Science magazine described euphoria as "a high sounding name" meaning "feeling fit": making life worth living, motivating drug use, ill formed in certain mental illnesses. Robert S. Woodworth's 1921 textbook Psychology: A study of mental life, describes euphoria as an organic state, the opposite of fatigue, "means about the same as feeling good."In 1940 The Journal of Psychology defined euphoria as a "state of general well being... and pleasantly toned feeling."
A decade finding ordinary feelings of well being difficult to evaluate, American addiction researcher Harris Isbell redefined euphoria as behavioral changes and objective signs typical of morphine. However, in 1957 British pharmacologist D. A. Cahal did not regard opioid euphoria as medically undesirable but an effect which "enhance the value of a major analgesic." The 1977 edition of A Concise Encyclopaedia of Psychiatry called euphoria "a mood of contentment and well-being," with pathologic associations when used in a psychiatric context. As a sign of cerebral disease, it was described as bland and out of context, representing an inability to experience negative emotion. In the 21st century, euphoria is defined as a state of great happiness, well-being and excitement, which may be normal, or abnormal and inappropriate when associated with psychoactive drugs, manic states, or brain disease or injury. Hedonic hotspots – i.e. the pleasure centers of the brain – are functionally linked. Activation of one hotspot results in the recruitment of the others.
Inhibition of one hotspot results in the blunting of the effects of activating another hotspot. Therefore, the simultaneous activation of every hedonic hotspot within the reward system is believed to be necessary for generating the sensation of euphoria. Many different types of stimuli can induce euphoria, including psychoactive drugs, natural rewards, social activities. Affective disorders such as unipolar mania or bipolar disorder can involve euphoria as a symptom. Continuous physical exercise aerobic exercise, can induce a state of euphoria. Exercise is known to affect dopamine signaling in the nucleus accumbens, producing euphoria as a result, through increased biosynthesis of three particular neurochemicals: anandamide, β-endorphin, phenethylamine. Euphoria can occur as a result of dancing to music, music-making, listening to arousing music. Neuroimaging studies have demonstrated that the reward system plays a central role in mediating music-induced pleasure. Pleasurable arousing music increases dopamine neurotransmission in the dopaminergic pathways that project to the striatum.
5% of the population experiences a phenomenon termed "musical anhedonia", in which individuals do not experience pleasure from listening to arousing music despite having the ability to perceive the intended emotion, conveyed in passages of music. The various stages of copulation may be described as inducing euphoria in some people. Various analysts have described either the entire act of copulation, the moments leading to orgasm, or the orgasm itself as the pinnacle of human pleasure or euphoria. A euphoriant is a type of psychoactive drug. Most euphoriants are addictive drugs due to their reinforcing properties and ability to activate the brain's reward system. Dopaminergic stimulants like amphetamine, cocaine, MDMA, methylphenidate are euphoriants. Nicotine is a parasympathetic stimulant. Chewing areca nut (se
The boiling point of a substance is the temperature at which the vapor pressure of a liquid equals the pressure surrounding the liquid and the liquid changes into a vapor. The boiling point of a liquid varies depending upon the surrounding environmental pressure. A liquid in a partial vacuum has a lower boiling point than when that liquid is at atmospheric pressure. A liquid at high pressure has a higher boiling point than when that liquid is at atmospheric pressure. For example, water at 93.4 °C at 1,905 metres altitude. For a given pressure, different liquids will boil at different temperatures; the normal boiling point of a liquid is the special case in which the vapor pressure of the liquid equals the defined atmospheric pressure at sea level, 1 atmosphere. At that temperature, the vapor pressure of the liquid becomes sufficient to overcome atmospheric pressure and allow bubbles of vapor to form inside the bulk of the liquid; the standard boiling point has been defined by IUPAC since 1982 as the temperature at which boiling occurs under a pressure of 1 bar.
The heat of vaporization is the energy required to transform a given quantity of a substance from a liquid into a gas at a given pressure. Liquids may change to a vapor at temperatures below their boiling points through the process of evaporation. Evaporation is a surface phenomenon in which molecules located near the liquid's edge, not contained by enough liquid pressure on that side, escape into the surroundings as vapor. On the other hand, boiling is a process in which molecules anywhere in the liquid escape, resulting in the formation of vapor bubbles within the liquid. A saturated liquid contains as much thermal energy. Saturation temperature means boiling point; the saturation temperature is the temperature for a corresponding saturation pressure at which a liquid boils into its vapor phase. The liquid can be said to be saturated with thermal energy. Any addition of thermal energy results in a phase transition. If the pressure in a system remains constant, a vapor at saturation temperature will begin to condense into its liquid phase as thermal energy is removed.
A liquid at saturation temperature and pressure will boil into its vapor phase as additional thermal energy is applied. The boiling point corresponds to the temperature at which the vapor pressure of the liquid equals the surrounding environmental pressure. Thus, the boiling point is dependent on the pressure. Boiling points may be published with respect to the NIST, USA standard pressure of 101.325 kPa, or the IUPAC standard pressure of 100.000 kPa. At higher elevations, where the atmospheric pressure is much lower, the boiling point is lower; the boiling point increases with increased pressure up to the critical point, where the gas and liquid properties become identical. The boiling point cannot be increased beyond the critical point; the boiling point decreases with decreasing pressure until the triple point is reached. The boiling point cannot be reduced below the triple point. If the heat of vaporization and the vapor pressure of a liquid at a certain temperature are known, the boiling point can be calculated by using the Clausius–Clapeyron equation, thus: T B = − 1, where: T B is the boiling point at the pressure of interest, R is the ideal gas constant, P is the vapour pressure of the liquid at the pressure of interest, P 0 is some pressure where the corresponding T 0 is known, Δ H vap is the heat of vaporization of the liquid, T 0 is the boiling temperature, ln is the natural logarithm.
Saturation pressure is the pressure for a corresponding saturation temperature at which a liquid boils into its vapor phase. Saturation pressure and saturation temperature have a direct relationship: as saturation pressure is increased, so is saturation temperature. If the temperature in a system remains constant, vapor at saturation pressure and temperature will begin to condense into its liquid phase as the system pressure is increased. A liquid at saturation pressure and temperature will tend to flash into its vapor phase as system pressure is decreased. There are two conventions regarding the standard boiling point of water: The normal boiling point is 99.97 °C at a pressure of 1 atm. The IUPAC recommended standard boiling point of water at a standard pressure of 100 kPa is 99.61 °C. For comparison, on top of Mount Everest, at 8,848 m elevation, the pressure is about 34 kPa and the boiling point of water is 71 °C; the Celsius temperature scale was defined until 1954 by two points: 0 °C being defined by the wate
Alkyl nitrites are a group of chemical compounds based upon the molecular structure R-ONO. Formally they are alkyl esters of nitrous acid, they are distinct from nitro compounds. The first few members of the series are volatile liquids; the compounds have a distinctive fruity odor. Another encountered nitrite is amyl nitrite. Alkyl nitrites were and still are used as medications and chemical reagents, a practice which began in the late 19th century. In their use as medicine, are inhaled for relief of angina and other heart-related symptoms of disease. However, when referred to as "poppers", alkyl nitrites represent recreational drugs. Organic nitrites are prepared from alcohols and sodium nitrite in sulfuric acid solution, they decompose on standing, the decomposition products being oxides of nitrogen, the alcohol, polymerization products of the aldehyde. They are prone to undergo homolytic cleavage to form alkyl radicals, the nitrite C-O bond being weak. Tert-Butyl nitrite has been shown to be an effective reagent for the selective nitration of phenols and aryl sulfonamides n-Butyl nitrite and ammonia convert phenylhydroxylamine to its nitrosamine derivative cupferron.
Pyrrolidine is a substrate for ethyl nitrite. Alkyl nitrites are used in the formation of oximes with the stronger carbon acids and acid or base catalysis for example in the reaction of 2-butanone, ethyl nitrite and hydrochloric acid forming the oxime, the similar reaction with phenacyl chloride, or the reaction of phenylacetonitrile with methyl nitrite and sodium hydroxide. An isolated but classic example of the use of alkyl nitrites can be found in Woodward and Doering's quinine total synthesis: for which they proposed this reaction mechanism: Amyl nitrite is used medically as an antidote to cyanide poisoning, The light alkyl nitrites cause the formation of methemoglobin wherein, as an effective antidote to cyanide poisoning, the methemoglobin combines with the cyanide to form nontoxic cyanmethemoglobin. First responders carry a cyanide poison kit containing amyl nitrite