In the traditional preserved egg making process, heavy metals such as lead or copper are often added to the dipping solution to solidify protein. According to the regulations of Taiwan Province Provincial Health Department, the lead content of preserved eggs should not exceed 2ppm, and the copper content should not exceed 8ppm. Moreover, agricultural administrative units also help operators to produce high-quality preserved eggs, so that the lead content does not exceed 0.3ppm and the copper content does not exceed 5ppm. Therefore, the dip of qualified manufacturers does not add heavy metals, or the content is very small, but now there are lead-free preserved eggs. In fact, adults also have lead-free preserved eggs, but children should eat less. Safe to eat and nutritious! If you eat preserved eggs often, it will lead to lead poisoning. This will lead to insomnia, inattention, anemia, joint pain, mental retardation, brain function and other symptoms. In addition, lead will replace calcium, affect calcium intake, and may also cause calcium deficiency. Suggestion: Add some old vinegar when eating preserved eggs, which can sterilize, neutralize some alkalinity of preserved eggs and taste more delicious.