There are a lot of people on many different sites and forums that yell, kick and scream that sodium borate (or tetraborate) is horrible and toxic.
Then there are people on the other side of the coin that use it cleaning and in skincare products.
If you are doing your research on sodium borate and your research uses sodium borate and boric acid interchangeable, find a new article. They are NOT the same thing.
Personally,I fall somewhere in between. I think it's a great green cleaner for anything that does not go directly on your skin.
Currently, the only MamaSuds product that I use it in is Laundry Soap. It's the last ingredient on the ingredient list, which means there is not much in your gallon of Laundry Soap.
I respect my customer's choice/opinion on what they use in their homes so I offer borate-free laundry soap. I make it this way about once a month so it's no trouble at all to omit it.
Does it clean well without? Really, it depends on your water. The people who ask for borate-free (and can vouch for it's effectiveness) all have city water.
In order for the soap to penetrate fibers the water has to be an ideal pH and water that is hard (full of minerals) makes it difficult for the soap to penetrate the fibers to clean them. Borate increases the effectiveness of the soap by making the water stable for the soap to work at it's best.
Also- this is a little nerdy but borate also does a really cool thing when it's mixed with water- it releases hydrogen peroxide which acts as a bleach and also makes the water more alkaline which kills bacteria and fungus (something cloth diaper-ers know a lot about). Because my soap is all natural and made of olive oil soap, it rinses free (no residue) so even though you washed with it, it's completely rinsed out and therefore isn't being absorbed by your skin.
So- do I think it's safe? Yes, as a cleaner. Not as an ingredient in body wash, shampoo or skincare.