The discipline of chemistry has made agricultural chemicals, such as fertilizer and pesticides, available to society.

Which is a negative effect of these chemicals on society?

Well, you can't use this word for word, but a good answer would be something like:

Pesticides release harmful chemicals into the air, not only making it toxic and unsafe for us, but it also has the potential to kill off insects. This affects the ecosystem as well, as it reduces the available food source for larger animals such as birds, which in turn, affect another species.