fact that any substance under certain conditions, can become toxic.Any of these may to some extent adversely affect human health, there is only a question of dose or concentration, intensity and duration of exposure.For example, ordinary water from deep wells contaminated with hazardous chemicals, usually collected in a shallow layer of soil.There it is absorbed by plants and then together with them can get into our body.So the water (or rather, toxins in it) in a short time can have a significant adverse impact on human health.In addition, the life-giving oxygen is, in certain situations and circumstances, really dangerous toxin.The air, especially in big cities, polluted many hazardous substances that threaten the health and even often - life.
toxicity may be widely available and used salt (sodium chloride), and even glucose, of course, if they are consumed in large enough quantities.Rich salt sea water completely undrinkable because of the high concentration of these salts are highly toxic.
very dangerous to your health as distilled water.The paradox is that it is absolutely pure water, but it is precisely this harmful.It does not have any additional ingredients required for life.This water is totally absorbed by the body, and if used consistently, she poisons you.
Ideally inert noble gases are not toxic to humans.Thus theoretically it is not toxic nitrogen (the main component of air), hydrogen or a gas containing simple aliphatic hydrocarbons, such as methane, ethane and propane.But when a person living in poorly ventilated areas, breathes constantly reactive gas - due to the increase of its concentration in the atmosphere of the room - he poisons himself.Thus, from the air displaces oxygen - comes the typical symptoms of acute ischemia of the body.So - in theory, it is not a toxic substance becomes in this particular situation adversely affecting human health.
concept toxicity of various substances in accordance with modern knowledge is understood much broader than before.List of hazardous substances is not limited to the well-known "historical" poisons, such as arsenic, cyanide, strychnine, curare alkaloids of hemlock (hemlock), snake venom, toxins present in some mushrooms.It is complemented by numerous substances which, in certain situations and conditions of the safest become toxic.While others may be dangerous to the health and even the lives of people.
best example of just such a substance widely consumed in various forms, is ethanol.This is something to be poisoned in one day.Using very specific doses of ethanol in the composition of drugs is safe for most people.Exceeding the dose or combination with other medication and other chemicals can be very dangerous.As a result of adverse drug interactions ethanol can cause very serious symptoms as a result of damage to organs and systems, and the violation of their functions.
worth noting that there are people with a certain genetic susceptibility to pathological effects of substances recognized as toxic.Simply put, they can not be poisoned by poison than any other person.It is difficult to say whether there is such a "immunity" as a result of constant exposure to a toxin or to have another reason.Of course, under certain conditions, may appear adaptive defense mechanisms, but there is no scientific basis for this.Simply, there are people insensitive, such as snake venom.Or those who easily tolerate large doses of ethanol (of its kind, is also a powerful toxin).
Truth and myths about the toxic substances
public knowledge that is dangerous to human health and that there is a serious threat, obviously deepens and expands.Yet this is not enough, especially in certain circumstances, when, unfortunately, people often misleading.
example, there is a widespread perception (even among some doctors) that metallic mercury - a very dangerous poison.Often parents who have a house has a mercury thermometer, worried it will break and all the poison in one day.And yet such is not metallic mercury thermometers!There are the usual liquid mercury vapors which can also be dangerous, but only if they inhale large amounts and for a long time.Metallic mercury, in contrast, even dangerous in microdoses, like many inorganic compounds molten metal.
toxicity of certain products is determined by many people and is estimated to be completely incompetent.For example, based on their taste, flavor and appearance.Many people believe that they got a poisonous mushroom because it is bitter to the taste, or because they are bottom of the cap does not darken a result of oppression or under the influence of light.In fact, if the fungus bitter or not, it darkens on exposure to light.From a toxicological point of view, all this absolutely does not matter!Toxicity of mushrooms depends on the availability of toxic substances in them, that the human nose or other simple methods can not detect.
Many times it happened that some people mistakenly drank a variety of toxic compounds containing ethylene glycol.For example, the brake fluid, which is a very dangerous poison.In almost every case, a man was convinced of the non-toxic liquid, in particular, precisely because it was pleasant to the taste.
meth almost symbolically considered to be one of the worst and most dangerous poisons for humans.In fact they are in the same degree of toxicity as other forms of ethyl alcohol.
Natural gas, which is widely used today, it is considered very toxic, while as soon as the release of incomplete combustion of carbon monoxide makes it very dangerous to health and life.Natural gas is actually another reason for initially dangerous to humans - it accumulates in closed rooms.In addition, an attempt to take oxygen from him, he may suddenly explode with great force.Bad breath often causes fear and leads to false judgments about the alleged toxicity.But not all unpleasant smelling gases are toxic!Few people know that emitted during incomplete combustion of natural gas, carbon monoxide is completely odorless, but several times more dangerous.This is something to be poisoned - one day here is opposed only a couple of hours.That's enough to get a lethal dose.
Despite many shortcomings and gaps in knowledge that are available to the modern society, the risks of toxicity of various substances people know quite a lot.But sometimes erroneous myths in this field is enough.In any case, the recognition of the threat better than its negation.