Final answer:
The requirements for lead-acid and nickel-cadmium battery safety are specified in regulations, such as Directive 2006/66/EC of the European Union, which aims to improve the environmental performance of batteries.
Step-by-step explanation:
The requirements for lead-acid and nickel-cadmium battery safety are specified in regulations and directives. For example, the European Union has Directive 2006/66/EC that prohibits the placing on the market of portable batteries containing more than 0.002% of cadmium by weight, aiming to improve the environmental performance of batteries.
Additionally, there may be industry standards and guidelines that define safety requirements for these types of batteries.