Sulfite is composed of sulfite ion (SOthree2-）Compounds with other metal ions (or ammonium ions).
On October 27, 2017, the list of carcinogens published by the International Agency for Research on Cancer of the World Health Organization (WHO) was preliminarily sorted out for reference, and sulfite was included in the list of category 3 carcinogens.[2]
Sulfite is an oxy acid salt whose acid radical is sulfite SOthree2-。Its acid anhydride is sulfur dioxide SOtwo, sulfite is generally not present in surface water.If the sulfite discharged into the outlet water comes from municipal sewage, it will be easily oxidized to sulfate.
chemical property
In sulfite and sulfite, the oxidation number of sulfur is+4, so sulfite and sulfite have both oxidizability and reducibility, but their reducibility is main.Sulfite bisulfuric acid has stronger reducibility.
Alkali metal sulfites are easily soluble in water. Due to hydrolysis, the solution is alkaline. The positive salts of other metals are slightly soluble in water, while all acid sulfites are easily soluble in water.Sulfite decomposes easily when heated.E.g. 4NatwoSOthree=3NatwoSOfour+NatwoS sulfite or acid sulfite will decompose when encountering strong acid and release SOtwo, which is also a small amount of SO produced in the laboratorytwoA method of.
Sulfite has many practical uses. For example, calcium bisulfite is widely used in the paper industry, that is, it is used to dissolve wood to make pulp, sodium sulfite and sodium bisulfite are widely used in the dye industry, and also used as a dechlorination agent when bleaching fabrics.In addition, sodium bisulfite is used as an inhibitor in agriculture to promote the increase of rice, wheat, rape, cotton and other crops, which is due to NaHSOthreeIt can inhibit the photorespiration of plants, thus improving net photosynthesis.
Use hazard
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use
Sulfite is a kind of sulfate that has been widely used in the world for a long timefood additives, can be used asFood bleach, preservative;It can inhibit non enzymatic browning and enzymatic browning, prevent food browning, prevent fruit from blackening, and prevent fresh shrimp from generating black spots;In acid medium, it is also a very effective antibacterial agent.
For human body, sulfite ion is originally the product of the metabolic process of sulfur-containing amino acids. Therefore, there is sulfite oxidase that can oxidize sulfite in the body. The sulfite oxidase is most abundant in the liver. Other organs, such as the heart and lung, also exist in the cell mitochondria. It is an essential enzyme for human body.Sulfite oxidase is not induced by the intake of sulfite in the body in vitro. This enzyme must contain active molybdenum. The sulfite entering the body is catalyzed by sulfite oxidase and combined with oxygen to generate harmless SOfour2-。
Sulfite including NatwoSO3，KtwoSO3，NaHSO3，CaSO3，KHSO3，NatwoStwoO3，NatwoStwoO5，KHStwoOfive, ADI value of each sulfite (based on SOtwo() are 0 ～ 0.7 mg/kg · bw.In addition, sulfur can also be used as bleaching agent, but only for fumigation.In fact, the secondary sulfur fumigation of syrup is a traditional process in the sugar industry and a necessary control process for quality control.According to the national standard, the residual amount of sulfite (sulfur) in white sugar (based on SOtwo) shall not exceed 0.05g/kg.
harm
The experiment shows that using NaHSOthreeThe development of rats was inhibited after feeding 0.1% diet for 2 years;With NatwoSOthreeRats fed with 0.1% feed for 2 years suffered from neuritis, bone marrow atrophy and other diseases.
When people take 1g of sulfite a day, it will not cause obvious harm. Taking 4-6 g of sulfite can cause gastrointestinal disorders and severe diarrhea.Chronic poisoning can cause headaches, kidney disorders, red blood cells and hemoglobin reduction and other symptoms.In addition, because sulfur contains lead, arsenic, thallium, etc., these toxic substances can enter food during fumigation.The following table shows the median lethal dose (LD) of several sulfitesfifty）Or lethal dose (LD).
After sulfite enters the body, it is very easy to pass an electronoxidationformationSulfur trioxideAnionic radical (SOthree-），SOthree-Can be used with OtwoRapid reaction to generate superoxide anion radical Otwo-。
Recent studies have shown that sulfites can damage chromosomes and DNA.Sodium bisulfite and sodium sulfite (1:3) biological test solution can significantly increase the frequency of chromosome aberration (CA) in Chinese hamster lung fibroblasts (CHL), and there is a clear dose effect relationship.At low concentration, it mainly induces chromatid distortion, while at high concentration, it can cause both chromatid distortion and chromatid distortion.The study also found that the longer the cells were treated, the lower the minimum concentration required to cause genetic damage.When CHL cells were treated with it for 24 hours, CA increased significantly at the concentration of 5 mmol/L;If treated for 48h, the concentration of 1mmol/L can induce significant increase of CA.
At the same time, after intraperitoneal injection of sodium bisulfite and sodium sulfite (1:3) biological test solution into mice, it was found that the DNA of hippocampal neurons was damaged.When its concentration was 1.000g/kg · bw, the damaged cells of male mice reached 99.33%, and the length of DNA migration of cells reached 29.13 μ m, while the damaged degree of DNA of hippocampal neurons of female mice reached 95.33%, and the length of DNA migration of cells reached 20.94 μ m.Even at a lower concentration (0.125g/kg · bw), the length of DNA migration increased significantly.
In addition, the study points out that sodium bisulfite can increase the rate of sister chromatid exchange (SCE) and micronucleus (MN) in human blood lymphocytes, delay the mitotic cycle of lymphocytes and decrease the mitotic index of lymphocytes, and these effects have a significant dose effect relationship.
The mechanism of these genetic effects is still unclear and needs further research, but people have a new understanding of the harm of sulfite.[1]
