All my washing of glassware in the lab last week has paid off. We got great experimental data. There was no contamination in our lower Franz cell chamber. We saw lead where we were supposed to see lead, we and saw no lead where we shouldn’t!
Previously published experimental data had shown that lead acetate passes through the skin of mice. We therefore applied lead acetate to our pigskin samples. After 24 hours, we found lead in the saline of our Franz cells. This was our positive control experiment. We expected to see something and we did.
We also applied distilled water with no lead (less than 0.1 part per billion) to pigskin samples. After 24 hours, we found no lead in the saline of our Franz cells. This was our negative control experiment. We expected to see nothing, and we did.
The combination of these two pieces of data told us that our experimental system is working as designed. This is great because we also tested a simple makeup. It was an oil and lead carbonate mixture. We saw that lead passed through pigskin from this makeup!
We saw a tiny, tiny amount of lead from the makeup. It could only be seen because of the multiple washes of the Franz cells. However, this result says that very small amounts of lead from a white lead makeup could pass through the skin.
How small? Well, one hundred times less lead passed through the skin from the makeup than from the lead acetate. Only 0.04% of the lead from the applied lead acetate passed through the skin after 24 hours.Only 0.0004% of the lead from the white lead makeup passed through the skin after 24 hours.
This is a tiny proportion. However, balanced against this is the fact that these makeup recipes contain a lot of lead. Recipes often say to add an ounce (28 g) or two of lead carbonate. In addition, women covered a large skin area with makeup: they painted both their face and their decolletage.
There is much we do not know about what would happen to this lead from makeup when it enters the body. We only measured total lead in the saline, not what form of lead. However, a worst case (and probably unfairly high) estimate would be that all of the lead stayed in the body. In this scenario, we assume that it was carried in the blood.
Assuming this, my calculations say that one application of this makeup to a woman’s face and decolletage would not make her ill. In fact, she would not notice any difference in her health at all! We would be able to see and measure the projected increase in blood lead level in a modern urban Canadian woman. However, the increase would not put that woman outside of today’s ‘normal’ and low blood lead range.
This is a calculation of the potential health effects from one application of makeup. What would happen with repeated applications is a question I cannot yet fully answer.
We now need to run this experiment again (and again!). We need to replicate the data to be confident that this result is real. However, today I am really happy. We have our first glimpse of just how dangerous a particular lead makeup might be!