Go outside with a pair of scissors and snip the slugs in half. Honestly, if you do this persistently you can make a big dent in the local slug population. It's gruesome but effective. The carcasses will dry up and disappear in no time.
There are commercial slug baits which you can use to protect individual plants but broadcasting these slug pellets over a wide area might not be be that effective. It would usually just be sprinkled in a garden bed. Look for slug baits which contain "Iron Phosphate" — it's non-toxic.
Another product is "diatomaceous earth", a fine powder made from pulverized rock. They don't like to crawl through this stuff. It's also non-toxic.