Where do the heavy metals in textiles and clothing come from? What harm does it have to human health?
Heavy metals in textiles mainly come from the use of heavy metal complex dyes and chemical auxiliaries in the dyeing and finishing process, the absorption and enrichment of bears in nature during the growth of natural fibers, and cross-contamination in the textile production process. Moderate amounts of certain heavy metals are beneficial to human health. However, after being absorbed by the human body, excessive heavy metals can easily accumulate in the liver, bones, kidneys, heart and brain, causing harm to the digestive system, urinary system, organs, skin, bones and nervous system.
What regulations do domestic and foreign standards and laws have on the content of heavy metals in textiles?
The domestic standard GB/T 18885-2009 “Technical Requirements for Ecological Textiles” regulates antimony (Sb), arsenic (As), lead (Pb), cadmium (Cd), mercury (Hg), copper (Cu), and chromium (Cr). The content of heavy metals such as cobalt (Co) and nickel (Ni) has been limited.
There is the international ecological textile standard OEKO-TEX Standard 100-2010 abroad. There are many types of heavy metals. According to different types of heavy metals and the classification of textile products, limit values are given in the standard.
For extractable heavy metals, the two sets of standards set the same limit. Among them, OEKO-TEX Standard 100-2010 sets a limit on the total amount of heavy metals lead and cadmium. For extractable lead, the limit for Class I products is 0.2mg/kg, and for Class II- Class IV products are all 1.0 mg/kg, and all types of extractable cadmium products are 0.1 mg/kg. As for the heavy metal content in the digested samples, lead is 90.0 mg/kg and cadmium is 40.0 mg/kg. Lead is 90.0 mg/kg and cadmium is 40.0 mg/kg. GB/T 18885-2009 notes on the heavy metal lead that “lead and lead alloys are prohibited from being used in metal accessories.”
What issues should be paid attention to when detecting heavy metal content in textiles
At present, the measurement methods include plasma atomic emission spectrometry (ICP-AES), atomic absorption spectrometry (AAS), atomic fluorescence spectrometry (PFS), colorimetric methods, etc.
The current difficulty in detection is that the amount of free substances we can detect is also related to factors such as the color fastness of the textile, the degree of washing, and the extraction conditions. There is a lack of standard testing methods for the total amount of heavy metals in China. As a testing procedure, the OEKO-TEX standard only provides rough provisions on extraction conditions and testing instruments, and lacks a description of specific analysis steps.
When testing, attention should be paid to the sensitivity that can be achieved by different testing methods, and at the same time, attention should be paid to whether the element to be measured is volatile, which may lead to inaccurate test results. For example, lead and cadmium are two elements that are easy to volatilize when samples are pretreated by dry ashing method, and the results obtained by pretreating samples by microwave digestion are quite different. In this case, additives can be added during the sample pretreatment process by dry ashing method to reduce the volatilization of the elements to be measured and improve the accuracy of the inspection results.
For manufacturing companies, how to avoid quality problems with excessive heavy metal content?
As a producer of textile fiber raw materials, when planting plant fibers, try to select pollution-free or low-pollution land; when producing chemical fibers, avoid using initiators and catalysts containing heavy metals in slicing production, and during the spinning process Avoid using antibacterial agents containing heavy metals and actively use heavy metal-free alternatives. As a textile fiber and clothing processing enterprise, it should communicate with manufacturers of dyeing chemicals and clothing accessories, and conduct more systematic research on the screening of dyeing chemicals and accessories based on the product information of each manufacturer, in order to improve the quality of textile fibers and clothing. During processing, avoid related dyeing agents and clothing accessories containing heavy metals.
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