Since childhood, many have been told how dangerous it is to break the mercury thermometer, because the poisonous pairs of rapidly evaporating substances can cause serious damage to health. We decided to check how justified such warnings are.
The question “what to do if a thermometer crashed” worries many Internet users, therefore, by their explanations on this topic, official authorities are divided (such materials can be found, for example, on the official website of the mayor and the government of Moscow mos.ru, on sites Ministry of Emergencies of the Russian Federation And Rospotrebnadzor), and various media (RIA "News", RBC, TV channel "Science"). Especially asking excites probability poison spilled from thermometer mercury, as well questionHow long it is forbidden go to room, Where Shattered thermometer.
Mercury is the so-called transition metal, at room temperature it is a heavy silver-white liquid. Mercury and many of its compounds Poisonous, they have a toxic effect on the nervous, respiratory, digestive and immune systems, and are also able to damage the kidneys, skin and eyes. WHO attributes this metal to ten basic chemicals that pose a danger to humans.
Exists Three forms of mercury: elementary (or metallic), inorganic and organic (represented, for example, toxic methylctuta). They differ in the degree of toxicity and effects on a person. The usual mercury thermometers contains elementary mercury, in the domestic measuring device usually located 1 g of mercury.
From the outside world, substances into the body fall into three main ways: they eat, inhale, or they are in contact with the surface of the skin.
Eating mercury from a broken thermometer is absolutely not dangerous, since the body Has sucks less than 0.1% absorbed mercury. Moreover, the medical literature describes an amazing happening: a man intentionally swallowed 220 ml (3 kg) of liquid mercury, when applying for medical help, he complained about tremor, irritability and fatigue, but the doctors did not find any lesions in the gastrointestinal tract or kidneys, while the extently high concentrations of metal were recorded in the blood and urine. Most of the mercury left the body of this person through the intestines over the next ten days, laboratory tests returned to normal after another ten months. For comparison, a fatal outcome causes the use of only 250 g of such a product that is familiar to everyone as salt. But eating the contents of 3,000 thermometers is not able to kill a person. IN reference book The “toxicological profile of mercury”, prepared by the Ministry of Health and Social Services of the United States, in the “Deadly occasions” section, no poisoning is generally described by swallowing pure mercury, only its diverse compounds.
In this case, organic mercury compounds are extremely dangerous with systematic use. The most toxic methylrtic is - it is formed when the elementary mercury is interacted with various microorganisms. Its main source is fish and seafood that accumulate this connection in the process of their life. The larger the fish, the greater the chance that its meat contains high concentrations of methylrthetics. The most resonant case of poisoning methyl. Fixed In Japan, where in 1932-1968 the plant, which produced acetic acid, drained liquid waste, including inorganic mercury, into the Gulf of Minamat. Fish and mollusks, which lived in coastal waters and accumulated methylthut in their organisms, were the basis of the diet of the local population. The victims complained about numbness and weakness in the legs and arms, a constant feeling of fatigue, a ringing in his ears, a deterioration in vision and hearing, inarticulate speech and clumsiness. In the most severe cases, the poisoners went crazy, paralysis and death occurred. Such poisoning of methylthutu was called a Minamat disease. True, there is no risk of its development due to a broken thermometer-in order to form methylentyot from elementary mercury, necessary Special microorganisms and algae that could process it and which do not live in apartments or private houses, but at the bottom of large reservoirs.
The second potential path with which mercury can enter the body is inhalation of its vapors. Mercury Starts evaporate already at a temperature of +16 ° C, so advice Trying to reduce the temperature in the room where the thermometer crashed is justified. Inhaled vapors the body assimilates in much more significant concentrations than the stomach sucks - about 80% of vapor They get In the lungs, and from where the blood is spread throughout the body. However, panic early: by death will lead Only inhalation of 2.5 g of mercury vapor, that is, it is necessary to break at least three thermometers in the impenetrable room and stay there for a while.
Acute, but not deadly poisoning in pairs of mercury Arrives at a concentration of 0.13–0.80 mg/m3. Typically, mercury from a thermometer forms several rather large balls, on the floor taking the shape of the hemispheres, which, firstly, are easy to remove, and secondly, their evaporation area will not be the largest. However, we consider the worst, albeit in many ways a hypothetical scenario: all the mercury leaked and broke into such drops that are not visible to the naked eye. Human capable The naked eye to distinguish objects up to 0.01 cm long, take this value by the diameter of each drop. Let effective evaporation occurs with two-thirds of the surface, since the hemisphere from the mercury lies on the floor with some part. We calculate the surface area of the entire sphere, and then the area of evaporation. The total area will be 3.14 * 10-4 cm2, and the evaporation area is 2.09 * 10-4 cm2.
Knowing the density of mercury and calculating the volume of one ball (0.52 * 10-6 cm3), you can find out its mass (7.07 * 10-6 G). Then you can calculate how many of these drops the same 1 g of mercury from the thermometer will break up. It turns out that in the worst situation on the floor there will be 141,500 the smallest particles of mercury with a total area of 45 cm2, and the area with which the metal evaporates will be 30 cm2. The speed of evaporation of mercury at room temperature is 0.002 mg/cm2 per hour. Thus, in an hour in the room, 0.06 mg of mercury will evaporate.
If you look at the maximum permissible concentration (MPC) of mercury, established legislative, namely 0.0003 mg/m3, then it may seem that mercury in the air a lot and soon poisoning will come. However, an important point is not taken into account here - the value of the MPC does not determine one -time consumption, but describes the impact over the period of time. We will transfer our calculations to specific housing. Since gaseous mercury will spread throughout all rooms, you should take into account the entire area, and not just the injured room. Let the case happen in an apartment with an area of 60 m2 with ceilings height of 2.7 m. The volume of such a room will be 160 m3. Since it is not hermetic, natural air exchange will occur (in the case of open windows are faster, but with closed air circulates both inside the house and gets from the street and penetrates out). Suppose that the volume of circulating air per hour will be 320 m3, that is, half the volume will change. We calculate the concentration taking into account these data and we will get that at the worst case it is 0.00018 mg/m in an hour3, which is even lower than the dose established by law. In other words, for acute poisoning, which occurs at a dose of 0.13-0.80 mg/m3, in the room you will have to break more than 720 thermometers.
Now let's try to calculate a long -term effect, for example weekly. Suppose a person who has broken a thermometer does not leave the apartment all week (according to the same worse scenario, the entire metal scattered into the particles invisible to the eye). It turns out that during this time about 0.03 mg of mercury will fall into the body (in fact, even less, since over time the mercury will evaporate more slowly). This indicator is also lower than the dangerous even in the most unfavorable case, so to be afraid that due to a broken thermometer, the apartment will become dangerous for a long time, unfounded.
The third potential path of poisoning is the penetration of mercury through the skin. However, mercury is too dense metal (13 times denser water) and Can't To absorb through the skin. At the same time, from the surface of the skin, it can still evaporate and poison the body with its pairs. It is not worth collecting spilled mercury with bare hands, because through cuts and other damage to the skin, metal can penetrate the bloodstream and negatively affect health.
Thus, the fear of poisoning with mercury due to the broken thermometer is exaggerated. It is really extremely toxic when inhaled the metal, however, in home thermometers it is contained in a very small amount. In order to get a dose of mercury, capable of leading to acute poisoning, you will have to break far from one thermometer, not to remove large drops and specially remain indoors. Another way is to intentionally inhale the vapors of the contents of three thermometers so that they completely fall into the lungs. A swallowed mercury ball cannot at all harm the body. There is also no great danger if the mercury affects the skin - it can only be absorbed through its damaged areas.
Image on the cover: Mercury Thermometer with Many Medical Capsules and Pills von Marco Verch Via ccnull.de
Read on the topic:
- Hugh Aldersi-Uyillams. Scientific fairy tales of the periodical table. An entertaining history of chemical elements from arsenic to zinc. "Liquid mirror (chapter about mercury)
- Why did cats die in the Minamat?
- Is it true that if there are apples with bones, you can be poisoned?
- Is it true that toothpastes with fluorine are dangerous for health?
- Is it true that to protect against infection immediately after exposure to radiation, you need to take iodine?
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