Blue crystal nano-lead barrier is not good for the human body. According to the relevant information query: If the content of lead in the human body exceeds the standard, it will cause many harms to the human body, and can cause developmental delays, mental retardation, etc. in children. The younger the child, the more serious the neurological damage will be and it will also affect the growth and development of the child. There may even be sensory impairments.