Drain openers usually contain many toxic products, so much so that they may be fatal if ingested. They are dangerous not only for your health but also for the environment and your plumbing systems. Even the less-toxic alternatives contain products that may be harmful to you, to fauna and flora. Therefore, it is recommended to avoid them and to use more natural solutions, listed below.
DIY
The best way to avoid clogged drains is to keep them clean. You can do so by placing a filter in your sink that will capture all food items, thus preventing them from going down the drain. Empty the filter often to prevent blockage, and always keep it clean to avoid accumulation of bacteria.
Also, as prevention, once a week, you can use boiled water and 2 ingredients to keep the drains open:
1/2 cup of baking soda
1/2 cup of white vinegar
Pour baking soda down the drain. Add white vinegar and cover the drain if possible. Let it sit for 5 minutes, then pour a kettle of boiling water down the drain.
This recipe can also be used to open clogged drains. You may have to repeat the procedure a few times thought according to the severity of the problem.
Just in case the clog is caused by grease, you can try another natural alternative, which requires only dish soap and hot water: boil some water and mix in a few tablespoons of dish soap. Then slowly pour the mixture down the drain (the hot water will help to liquefy the clog, and the soap will help it slide down the drain).
You can also use a plunger or a fish to pull out the garbage that is blocking the drain.
If none of these alternatives work, call your plumber!
Avoid the following chemicals in regular products
Ammonia: irritant and corrosive to the skin, eyes and respiratory and digestive tract
Dicholorodifluromethane: neurotoxic, irritant to eyes
Dimehtylbenzyl ammonium chloride: severe eye and skin irritant
Petroleum distillates: possible carcinogens depending on the degree of purification (possible contamination by butadiene), allergens
Potassium hydroxide (caustic potash or lye): irritant and corrosive to the skin, eyes and respiratory and digestive tract
Sodium hydroxide (caustic soda or lye): irritant and corrosive to the skin, eyes and respiratory and digestive tract
Sodium hypochlorite: irritant and corrosive to skin, eyes, and respiratory and digestive tract