Why is free solder necessary for the lead?

Lead is the material which is harmful to the human body with harmful heavy metals.
Specially, the composition taken in the human inside of the body due to the river and the subterranean water pulse pollution occurs in the lead drain from the reclaimed land of the waste.

It is aiming at the product-making which copes with better control of health than an employee's control and a natural environment in Nakagawa electric industry incorporated company.
It is returned to the product guidance.