The safest may be the one that does not contain chemicals. You can try Green Gobbler for this purpose. However, it may also kill plants you applied it on, and not only weeds.
I recommend you keep your gloves on while using any herbicide to avoid skin irritation or burns. If you are worried about small children or have pets in the house, you should keep the herbicide far from them.
Once you finish with the herbicide, you must carefully wash your working clothes and ensure your skin has not been in contact with the herbicide. Don’t stand near the sprayed area for too long, or you will have a headache.