Whitening soaps in the Philippines

I'm pretty okay with my skin. I have some scars on my legs which I'm not insecure about, I have hyperpigmentation on my face from my acne days, webs of stretch marks and (dark) yellow skin - and as I know there is no such thing as perfection, I never bothered doing anything special with my routine. Just normal skin care.

But recently, probably because I'm getting married in this year,  I've become wary of my very very dark elbows which really stand out from the rest of my arms. As a result, I've been trying to find easy to purchase (and safe) whitening products for my elbows. Just last Friday, I went to a local supermarket and found a whole aisle of whitening soaps of various local brands and ingredients. Yep, most of the Pinays are not very fond of their more skin-cancer resistant skin color for whatever crazy reason, contributing to the huge market for whitening products. I could go on ranting with that obsession, but that is fitting for a different post.

Some notable whitening ingredients are the following: glutathione, kojic acid, papaya extract, calamansi extract, and tretinoin (from a popular but badly used chemical peel). Some had baking soda in it, which I hope is there to balance out the chemicals in the soap, and also sodium laureth sulfate (which according to a quick Google-ing is safe but may be irritating to sensitive skin types). But there is an ingredient which I felt was the odd man out:

Titanium dioxide. (from Wikipedia)

If I found it in a sunscreen, I would not be surprised, as it is a common physical filter. What's weird here is I find it in a product which uses it not as a filter (because if that were, then the marketing people would've placed an SPF rating on it). I'm speculating that the manufacturers added this compound on their product because titanium dioxide is a known ingredient in white pigments (in paints, food, toothpaste, etc). In fact, this is why I do not like titanium dioxide in sunscreens - it whitens my skin the moment I apply it.

So the question is, do soaps containing this compound whiten the user's skin because of the known whitening agents' effectiveness or is it because of the compound itself? You decide.