Following up from my previous post, here’s an open question to Friends of the Earth:
What is your worst case estimate of the human health risk from titanium dioxide and/or zinc oxide nanoparticles in sunscreens?
What I am interested in is a number – a probability of a specific human health impact being caused by using a given amount of nano-sunscreen over a certain amount of time. Something like:
“In the worst case, it is estimated that using [number] grams per day of sunscreen comprising [percent] TiO2/ZnO nanoparticles over [number] days could lead to an [percent] risk of the user developing [disease].”
This can be based on an extrapolation of the current state of the science to a worst case scenario. But it must be plausible. And the calculations/sources to get to the end number must be transparent.
I’m asking because I am interested to see whether it is possible to place an upper bound on the safety of nanoparticle-based sunscreens, and whether this will be useful in moving the dialogue over nano-enabled sunscreens away from ungrounded speculation, towards evidence-based discussion.
So that’s the challenge. I’m hoping my good friends at Friends of the Earth will rise to it.