Quoting:
Environmental Hazards of Batteries
People are using more and more household batteries. The average person owns about two button batteries, ten normal (A, AA, AAA, C, D, 9V, etc.) batteries, and throws out about eight household batteries per year. About three billion batteries are sold annually in the U.S. averaging about 32 per family or ten per person.
A battery is an electrochemical device with the ability to convert chemical energy to electrical energy to provide power to electronic devices. Batteries may contain cadmium, mercury, copper, zinc, lead, manganese, nickel, and lithium which may create a hazard when disposed incorrectly.
http://ehso.com/ehshome/batteries.php
I started using rechargeable household batteries several years ago, and I bought 2 chargers for AA's which is the size I use the most. One charger is solar and the other plugs into an electrical receptacle. I need to get another charger that will charge other sizes. I paid less than $20 for each charger but it's been so long that I don't remember exactly what I paid.
One thing I found out is that the Radio Shack brands have a lower milliamperage than others and do not hold a charge as long. So, I also need some new batteries.