Not long ago, two state-level laboratories of East China Institute of Technology and Shanghai Xinhua Hospital jointly conducted lead-containing tests on the most commonly used faucets of 13 Shanghai households in Shanghai. The results showed that the lead content of nine leading soaking waters exceeded the national level. The standard is 5 micrograms per liter, of which the number of over-standards is 2-6 times, and the number of over-standards of Jiumu faucet has reached 18 times. The most serious lead precipitation of Lejia faucet reaches 173 micrograms per liter, exceeding the national standard 34. Times.
Many people do not know that the original tap water is polluted by lead and other harmful substances due to the problems of pipes and faucet materials. The Shanghai Consumer Protection Committee once found in the comparative test of faucet products that 22% of the sampled samples had lead exceeding the standard, and some products exceeded the standard by 20 times. The Beijing Consumers Association also tested some of the faucets sold in the market. In the major building materials market and supermarkets in Beijing, 50 kinds of faucet products were randomly purchased and commissioned by relevant departments. The results showed that in the 10-hour and 24-hour lead precipitation concentration tests, only two stainless steel samples were completely lead-free. Why is lead in tap water? How to prevent secondary pollution of tap water by tap water?
Where does lead lead to the analysis of the causes of lead in brass faucets?
Lead has a reason in brass faucets
At present, the main material for domestic production of faucets is brass HPb59, which requires less than 1.9% lead. Due to the lack of standards, some manufacturers use brass lead content of 3% to 6% in order to reduce costs and improve the cutting performance of brass. . The temperature of the faucet casting is generally 1053 ° C, and the melting point of lead is 327.5 ° C, so that lead is segregated on the inner and outer surfaces during molding, and the lead content on the surface is 3 to 5 times higher than the internal. The lead removal process can be used to remove lead from the surface. However, the water flowing in the faucet will destroy the surface of the lead-washing, forming "corrosion", and the internal lead ions are exposed again, so that the lead content precipitated increases. To this end, the United States has introduced low-lead copper to solve the problem of lead precipitation from materials.
Domestic and international lead limit standards and testing
The lead content of the faucet is expressed in two ways, one is the mass percentage of lead in the raw material, and the other is the number of micrograms of copper per liter of water after the dip test or expressed by the Q value. Need to remind consumers that this is two different concepts, the lead value of raw materials meets the requirements does not necessarily mean that the lead value of the leaching meets the requirements.
The NSF61 is the most representative in the United States, and the technical requirements and test methods of the domestic faucet JC/T1043-2007 "water nozzle lead precipitation limit" standard are the same as those of NSF61. JC/T1043 specifies at least 3 sets of samples of the same specification during the test period. From Monday to the same day, change the water every 2 hours, take the 2nd, 3rd, 4th, 9th, 10th, 11th, 16th, 17th, 18th and 9th days of immersion for 16 hours of water for testing. The JC/T1043 standard requires lead statistics. The value is less than 11ug (the mandatory new version of GB18145 issuance in 2014, the Q value is 5ug), which means that the Q value of lead leaching is related to the volume of the product and the stability of the product. The value of the device test. At present, the most authoritative testing institutions in China include the National Plumbing Hardware Testing Center and the China Quality Certification Center Guangzhou CQC Laboratory.
According to Professor Fu Songtao, deputy director of the Expert Committee on Lead Prevention and Control of the China Policy Science Research Institute, at present, China's water pipelines are gradually being replaced by galvanized iron pipes into plastic (such as PVC, Pe, UPVC, etc.) pipes, and most of the households still use taps. It is cast iron or copper alloy. The main components of copper alloy faucet are copper and zinc. In addition, there are various elements such as lead, aluminum, tin, iron and manganese. The lead element will precipitate after long-term contact with water, and the more lead content in the faucet material, the more precipitation.
In addition to faucets, cast iron pipes, copper pipes and plastic pipes also contain lead more or less. If these materials are used in water pipelines, it will also cause lead pollution.
Lead pollution pregnant women suffer the most
The child is anorexia and picky, not long, has been plagued by many parents. Experts reminded that the above situation should be taken to the hospital to test blood lead levels. According to statistics, the blood lead level will increase by 100 micrograms per liter, the height of the child will be 1-3 cm less, and the IQ will be reduced by 6-8 points. The blood lead level in infants and young children will be greater than 200 micrograms per liter. It is 7.4 times larger, and the possibility of dyslexia is 5.8 times larger.
Lead can cause multiple organ and multiple system damage to children, and damage to the brain is even irreversible throughout life. Lead accumulates in children, easily damages the nervous and endocrine systems, leading to mental retardation and growth retardation in children; affecting mineral absorption, causing deficiency of nutrients such as zinc, iron, calcium, etc., causing diseases such as picky eaters, anorexia, anemia and rickets; Gastrointestinal neurovascular system, leading to digestive system dysfunction, causing constipation, diarrhea and unexplained abdominal pain, etc.; with the severity of lead damage, prolonged, these conditions will be further aggravated. It is worth noting that very low levels of lead exposure can cause many children to have abnormal behaviors such as distraction, hyperactivity, decreased learning ability, irritability, and aggressiveness.
Lead pollution also causes great harm to pregnant women. Excessive blood lead will increase the possibility of miscarriage, premature delivery, premature rupture of membranes and stillbirth.
Drinking water overnight
According to the Beijing Consumers Association's test data on the concentration of lead in the faucet, the concentration of lead in most samples was 0.002 mg/L - 0.223 mg/L in 10 hours immersion, and the concentration of lead in the 24-hour immersion ranged from 0.001 mg/L. -0.208 mg/l. It is not difficult to see that the "overnight water" that the faucet is stranded has a higher lead metal content. Professor Fu Songtao suggested that residents can take some measures to reduce the risk of lead pollution in drinking water. First, when the tap water is deactivated for more than 6 hours, be sure to turn on the tap for 1-3 minutes before use. Second, many households now have hot water supplies, but it is best not to use it as drinking water or cooking because the amount of lead in hot water is many times higher than that of cold water. Third, when purchasing a faucet, be sure to choose a quality standard product, preferably a stainless steel faucet. The stainless steel material is lead-free and does not cause secondary pollution of lead to tap water.
It is understood that because the current national standards for faucets do not specifically impose mandatory regulations on lead content and precipitation, the lead inspection of domestic market sales has not used lead as a quality criterion. However, in recent years, the problem of lead contamination caused by cast iron and copper faucets has caused widespread concern in many countries. It is reported that the United States has enacted a lead-free bill, stipulating that the lead content of the faucet should not exceed 0.25%, and European and American countries are also actively formulating relevant bills. China is also about to launch a new national standard for faucets, and the limitation of lead precipitation will become the focus of the new standard. (Welcome to our WeChat public number: Jiuzheng ceramic sanitary ware network or jiuzhengtaoci, the latest and most professional industry information, investment agency joining information for you to continue to send, to help your career development!)
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