Acute toxicity of formaldehyde
Acute formaldehyde poisoning is manifested as irritation to skin and mucosa. Inhalation of high concentration formaldehyde can cause respiratory irritation, sneezing and coughing with burning sensation in nose and throat;
In addition, it can also induce bronchial asthma, pneumonia and pulmonary edema. One-time intake of formaldehyde through digestive tract can cause symptoms of digestive tract and systemic poisoning, corrosion and burn of mouth, throat and digestive tract, abdominal pain, convulsion and death. Skin contact with formaldehyde can cause allergic dermatitis, pigmentation, skin necrosis and other diseases. Oral intake of 10~ 20ml formaldehyde solution can lead to death. ?
In animal experiments, the LD50 of formaldehyde ingested by rats is 800mg/kg, that absorbed by rabbits through skin is 2700mg/kg, and that inhaled by rats through respiratory tract is 590mg/m? . ?
Chronic toxicity of formaldehyde
Long-term exposure to formaldehyde can reduce respiratory function, information integration function of nervous system, affect the immune response of the body, and have toxic effects on cardiovascular system, endocrine system, digestive system, reproductive system and kidney. Systemic symptoms include headache, fatigue, loss of appetite, palpitation, insomnia, weight loss and autonomic nervous disorder. Animal experiments also confirmed the pathological changes of the above related systems. ?
Formaldehyde mutation
Formaldehyde can cause mutations in Salmonella typhimurium and Escherichia coli with or without metabolic activation system. At 0.5 mg/m3? 、 1.0 mg/m？ And 3.0mg/m? After continuous dynamic exposure to formaldehyde for 72 hours, the micronucleus rate of polychromatic erythrocytes in bone marrow increased significantly. ?
Carcinogenicity of formaldehyde
2017101On October 27th, the list of carcinogens published by the International Agency for Research on Cancer of the World Health Organization included formaldehyde in the list of carcinogens. ?
The research animals found that exposure of rats to formaldehyde 15 micrograms per cubic meter 1 1 month can lead to nasal cancer. The latest research results released by the American Cancer Institute on May 12, 2009 show that chemical factory workers who are exposed to formaldehyde frequently are much more likely to die from cancers such as blood tumors and lymphoma than those who are less exposed to formaldehyde. 20 10 found that formaldehyde can cause nuclear gene mutation and chromosome damage in mammals. Formaldehyde has a combined effect with other polycyclic aromatic hydrocarbons such as benzopyrene, which will enhance toxicity.
In addition, formaldehyde also exists widely in nature, including human body and some plants. Scientific research has found that the blood of humans and other primates already contains trace amounts of formaldehyde. As a metabolite of amino acids, trace formaldehyde will not have much influence on human body, so there is no real concept of "zero formaldehyde".
Since formaldehyde can't be completely removed and doesn't need to be removed, how much indoor formaldehyde content will not affect our health?
"Standard for Indoor Environmental Pollution Control of Civil Construction Projects" GB 50325-2020 was jointly issued by the Ministry of Housing and Urban-Rural Development and the State Administration of Market Supervision, which stipulated that:
Standard for Indoor Environmental Pollution Control of Civil Building Engineering (GB/50325-2020 Standard Class I Building Engineering): formaldehyde ≤0.07mg/m? ; Benzene ≤0.06mg/m? ; TVOC≤0.45mg/m？ ; Toluene ≤ 0. 1.5 mg/m? ; Xylene ≤0.20mg/m? ; Ammonia ≤ 0. 1.5 mg/m? ; Radon ≤ 150Bq/m? ; Suitable for: houses, hospitals, old buildings, kindergartens, school classrooms, etc.
Standard for Indoor Environmental Pollution Control of Civil Building Engineering (GB/50325-2020 Standard Class II Building Engineering): formaldehyde ≤0.08mg/m? ; Benzene ≤0.09mg/m? ; TVOC≤0.50mg/m？ ; Toluene ≤0.20mg/m? ; Xylene ≤0.20mg/m? ; Ammonia ≤0.20mg/m? ; Radon ≤ 150Bq/m? ; Suitable for: offices, shops, hotels, entertainment places, libraries, gymnasiums, public places, etc.
What if formaldehyde exceeds the standard?
A, in addition to formaldehyde invalid method.
1, plants, all kinds of plants can absorb formaldehyde to a certain extent, but the effect of plants absorbing formaldehyde is not very good. The experiment of Environmental Technology Research Center of Shanghai Academy of Building Research shows that five pots of plants such as chlorophytum, Eupatorium odoratum, ivy, aloe and radish can absorb formaldehyde to a certain extent, but the actual load should be considered. Suppose there is a pot of plants in a cubic meter, then a house of 20 square meters is 3 meters high and 60 cubic meters in volume. There are three problems in placing 60 pots of plants in 60 cubic meters, even if the error is not considered: first, it cannot be placed. Second, even if it can be put in, the humidity is too high to live in for 24 hours. Third, even if it is put down like this, it will only remove about 7%-8%. Therefore, the effect of removing formaldehyde by plants is particularly limited.
The master's thesis of Kunming University of Science and Technology is based on Kalanchoe blossfeldiana, Pilea peperomioi des, Cafathea makoyana, Four Seasons Begonia, Oncidium, Mosquito (Geranium X Citrenella), Yushu (Crassula perforate), Podophyllum, Camptotheca acuminata, Rohdea japonica, Camptotheca acuminata, Cymbidium hybridum, Pelargonium, Pteris multifida, Dianthus trifoliata, Platycodon grandiflorum and cd-econ.com were used as experimental objects. It can be seen from the experiment that: 1. Each plant has a certain absorption capacity for formaldehyde, but it basically does not absorb it after 24 hours. Second, formaldehyde has certain toxic damage to plants, and the long-term test damage is more and more obvious. Thirdly, the temperature makes the absorption of formaldehyde by plants have obvious deviation.
2. Activated carbon. Bamboo charcoal package with activated carbon has a certain formaldehyde purification effect.
However, there are differences in bamboo charcoal package sold in the market: inferior unknown bamboo charcoal and activated carbon.
2. 1. Inferior and unknown bamboo charcoal does not have any formaldehyde purification effect, and dust leakage may occur in the outer packaging.
2.2. Activated carbon is specially treated carbon. Organic raw materials (husk, coal, wood, etc. ) heating under the condition of air isolation to reduce non-carbon components (this process is called carbonization), and then reacting with gas, the surface is eroded, resulting in a structure with developed micropores (this process is called activation). Because the activation process is a microscopic process, that is, the surface erosion of a large number of molecular carbides is point erosion, there are countless pores on the surface of activated carbon. Most of the micropores on the surface of activated carbon are between 2 and 50 nanometers in diameter. Even a small amount of activated carbon has a huge surface area, and the surface area per gram of activated carbon is 500~ 1500m2. Almost all applications of activated carbon are based on this characteristic of activated carbon. It can be seen from the characteristics of activated carbon that activated carbon does have adsorption and purification effect on formaldehyde.
Matters needing attention in purchasing formaldehyde-removed activated carbon:
(1) It is necessary to purchase activated carbon bags with intact outer packaging.
(2) Activated carbon should be packed in vacuum to avoid failure due to adsorption of other impurities during transportation.
(3) Outside in addition to formaldehyde, activated carbon can also adsorb indoor dust, bacteria, moisture, PM2.5 and other particles, and its adsorption capacity is limited.
(4) Activated carbon can only adsorb free formaldehyde in the air, but can't effectively adsorb formaldehyde that has not been released in particleboard, laminated board and composite board.
(5) Activated carbon has limited adsorption capacity and needs to be replaced regularly, otherwise it will be released again.
3, air purifier, filter with reference to the characteristics of activated carbon, short replacement cycle, expensive, IQ tax products.
4. Vinegar and acetic acid contain carboxyl groups, which are the basic chemical groups in organic chemistry. All organic acids containing carboxyl groups can be called carboxylic acids, which consist of one carbon atom, two oxygen atoms and one hydrogen atom, and the chemical formula is -COOH. Formaldehyde is an organic chemical with the chemical formula HCHO or CH? O, with a molecular weight of 30.03, also known as ant aldehyde, is a colorless irritating gas, which can irritate people's eyes and nose. The relative density of gas is 1.067 (air = 1), and the density of liquid is 0.8 15g/cm3(-20℃). Melting point -92℃, boiling point-65438 09.5℃. Soluble in water and ethanol. Aldehyde groups do not react with carboxyl groups. Therefore, vinegar can't be in addition to formaldehyde, and the volatile smell of vinegar can only cover it up. Actually, formaldehyde still exists.
Second, in addition to formaldehyde's cheap method
Ventilation. Ventilation is an effective and cheap method to reduce indoor formaldehyde, but it takes a long time, and the ventilation time of many decoration projects using inferior materials may be as long as 1-2 years. It should be pointed out that window ventilation is not called ventilation, and there can be ventilation indoors. Only when there is no convection in the window can free formaldehyde in the air be taken away. In addition, if a lot of non-solid wood boards are used in the decoration, ventilation alone is not enough. With the later life, or gradually distributed indoors, the rain that may appear at any time due to daily weather changes is also the trouble of opening and closing windows back and forth.
Three. Practical measures in in addition to formaldehyde
If you are in a hurry to move in or the ventilation is not very good, you can choose some in addition to formaldehyde products on the market or provide on-site service to in addition to formaldehyde. As far as scientific and technological development is concerned, formaldehyde is no longer an uncontrollable substance. The catalysis of photocatalyst and biological enzyme can effectively and quickly reduce the formaldehyde content, and in addition to formaldehyde will not recur for a long time. However, you must be cautious when choosing in addition to formaldehyde products or visiting in addition to formaldehyde service companies. For formaldehyde products or in addition to formaldehyde door-to-door service agencies, we suggest that you compare them from the following aspects:
(1) Don't blindly choose products because of the factors of product spokespersons, such as online celebrities bringing goods or celebrity endorsements;
(2) Don't blindly follow the brand size of in addition to formaldehyde products or the door-to-door aldehyde removal service company;
(3) Whether aldehyde-removing products have all national testing qualifications is the guarantee of family safety;
(4) Whether the service technician has the construction qualification is the guarantee of the governance effect;
(5) Whether aldehyde removal products will react with formaldehyde or other household substances to produce secondary pollution;
(6) Whether there is a true and qualified test report after aldehyde removal is the guarantee of life safety.
Summing up a few conditions, you can screen out more suitable in addition to formaldehyde products or visit in addition to formaldehyde institutions.