Materials, products and services - the Green Guide Online provides details of the life cycle environmental impacts of construction materials and components, and the Green Book is a free online database of products and services.
Spermicides are used globally for birth control, with or without condoms. As the only means of birth control, spermicides are rarely effective. However, in conjunction with condoms, spermicides are somewhat effective in birth control.
The birth control pill works by stopping sperm from meeting an egg (which is called fertilization). The hormones in the pill stop ovulation. No ovulation means there's no egg hanging around for sperm to fertilize, so pregnancy can't happen. The pill's hormones also thicken the mucus on the cervix.