The main raw material of glass is natural minerals, which are melted in a kiln at high temperature (the temperature of molten glass is as high as 1300℃), shaped and annealed to make glass products. Glass products have been used as food containers and tableware for thousands of years. Because of their reliable chemical stability and reusability, they are recognized as safe and excellent packaging materials and tableware in the world. According to Secretary-General Liu Jianping, "Because glassware itself has good chemical stability, it will not affect the color and taste of things inside. We must realize that even lead crystal glassware may lead to chronic lead poisoning unless we often eat acidic food preserved with lead crystal glassware for a long time.
But as a long-term storage of food (mainly wine, jam, spices, etc.) packaging containers. ), almost all the glass used in the market contains no lead at all, and there is no lead precipitation, not to mention the problem of lead poisoning. As for the use of lead crystal glass and tableware, it will not cause harm to human health because of its short use time. "
In view of the statement that some institutions believe that lead crystal glass wine utensils, water utensils and acidic drinks will lead to lead precipitation, the person in charge of Beijing Glass-Ceramics Quality Supervision and Inspection Center also said that from the current test results of related products, there is no such phenomenon. ?
Has the national standard been implemented? Although fining agents and colorants used in glass manufacturing contain some harmful components, the amount of these harmful components has been controlled as little as possible, and they have volatilized or formed other compounds during the high-temperature melting of glass. ? Secretary-General Liu Jianping told the reporter: "In fact, as early as June 5438+February 2005 1, the national standard GB 19778-2005" Allowable Leaching Limits of Lead, Cadmium, Arsenic and Antimony in Packaging Glass Containers "was implemented, and the standard was revised by ISO7086-2, and lead, cadmium and antimony were all included.
Judging from the current domestic glass production enterprises in China, most of them have the production conditions and production control means to ensure that their products meet the hygienic requirements of food, and trace harmful substances or components in glass will not migrate into food and will not cause harm to human health. The test results of the inspection organization also confirm that the content of harmful components in glass products is within the safe control range. "?
Judging from the export situation of daily-use glass industry in China in 2005, the export volume of lead crystal glass was 965,438+07,265,438+03 kg respectively, which were exported to UAE, Egypt, Australia, Russia, France, South Korea, Canada, Japan and other countries. ?
Facing the high quality requirements of lead crystal glassware in the international market, "the export situation of lead crystal glassware fully shows the safety of lead crystal glassware." Secretary-General Liu Jianping believes that domestic lead crystal glass meets the quality requirements and should be safe for human health. There are still three misunderstandings about lead crystal glassware in public opinion.
1. All glassware is contaminated by lead?
"At present, the glassware circulating in the market can be divided into ordinary glassware and crystal glassware. There are two kinds of crystal glassware, namely lead-containing crystal glassware and lead-free crystal glassware. Lead crystal glassware is also called crystal glassware. " Secretary-General Liu Jianping introduced that the vast majority of daily consumer goods in the domestic and international markets are ordinary glassware, which does not contain lead, and there is no problem of lead precipitation at all. Lead crystal glassware, due to the addition of lead oxide in the production process, has much higher refractive index, hardness, brightness and transparency than ordinary glassware, which belongs to middle and high-grade products in the consumer market and is mostly used as handicrafts. "?
It is understood that in 2005, China's daily-use glass industry imported 297,492 kilograms of lead crystal glass, while other glass imports reached13,237,775 kilograms, and lead crystal glass imports only accounted for 2.2% of ordinary glass imports. ?
Second, the use of lead crystal glassware is harmful to the human body? ? The most convincing argument against lead-containing crystal glassware is that "foreign experiments have proved that after adding 1 liter into crystal glassware, the lead content of brandy can be as high as 20000 μ g/liter in five years, far exceeding the lead content of beverages stipulated by environmental protection departments should be lower than 50 μ g/liter". In Japan, compared with lead precipitation from lead crystal glassware, 0.05- 1.2 ppm of lead was detected from whiskey bottles preserved in lead crystal glassware for nearly five years, although it was different from the lead content in natural foods (rice 1.5ppm, dried vegetables 1.8ppm, mushrooms1. This argument obviously contradicts the theory of "resistance".
Secretary-General Liu Jianping introduced that according to the requirements of allowable leaching limit of lead, cadmium, arsenic and antimony in packaging glass containers, the allowable leaching limit of lead in packaging glass flat containers is 0.8mg/dm, 1.5mg/L for small containers, 0.75mg/L for large containers and 0.5mg/L for storage tanks. Therefore, the use of lead crystal glassware that meets the quality standards will not cause harm to the human body, and it is a safe tableware.
Third, acidic substances can easily lead to lead precipitation from lead crystal glassware? ?
"It is undeniable that acidic substances do lead to lead precipitation, but the premise is that acidic substances should be stored for a long time, and the second is to reach a certain acidity." Secretary-General Liu Jianping analyzed this.
"The root cause of lead precipitation from lead crystal glassware mainly lies in the length of heat preservation time. In other words, only long-term consumption of acidic foods stored in lead crystal glassware will lead to chronic lead poisoning. " Secretary-General Liu Jianping believes that as a container for long-term storage of food, almost all common glass products are used in the market, which does not contain lead at all, and there is no problem of lead precipitation, let alone lead poisoning. ?
It is understood that 4% acetic acid is usually used as eluent when testing the lead dissolution of glass products in the laboratory. However, it is difficult for food, drink and wine in daily life to reach this acidity that allows lead precipitation.