There are four potential ways that lead can enter the human body. It can be ingested by eating or drinking. It can be inhaled as a powder or vapour. It could be injected. Finally, it can be absorbed directly through the skin. Not all lead compounds pass through the skin equally well. For example, tetraethyl lead is absorbed readily and is extremely dangerous. Lead carbonate, however, is not supposed to pass easily through the skin.
One of the main questions we are trying to answer at Toxic Allure is ‘Can lead from 18th century make-up be absorbed through the skin?’ The white lead in 18th century make-up is lead carbonate. Current science says this should not be readily absorbed. However, if a recipe transforms some of this lead to a different compund where it can readily be absorbed through skin, then the make-up is likely to be more deadly.
We are testing this using Franz cells. This is a system of two glass chambers, one on top of the other, separated by a membrane. In our experiments we use pigskin as the membrane. We put water with salts (saline) in the bottom chamber, touching the skin. We then place makeup on top of the skin in the upper chamber. We keep everything at body temperature, 37 degrees Celsius . After a few hours, we sample the liquid in the bottom chamber and see how much lead has passed through the pigskin.
This sounds easy. It is not! We are using a fine white powder that is dangerous if eaten or inhaled. The work all has to be done in a fume hood. We wear lab coats, arm protectors, two pairs of gloves, masks and eye protectors. The set-up is fiddly. The Franz cell upper chambers are only a few millimetres in diameter. The work is made more challenging because you are working while looking through a pane of glass. Finally, we have found that some make-up is hard to get into the upper chamber. We have had more than one frustrating failed experiment because we couldn’t get the make-up to sit evenly on the pigskin!
This week we have run lots of quality assurance Franz cell experiments. We ran experiments where distilled water replaced the makeup. We ran experiments with compounds that should pass readily through the skin. We have sent different batches of the saline we use to be analyzed for lead. We need to check for lead contamination in materials we use. We need to verify our cells are working properly.
Testing make-up recipes is going to be a long a slow process. We want to know how factors such as lead concentration, make-up composition and age of the make-up affect the amount of lead that passes through skin. We also want to know how time on the skin changes the amount of lead that gets into the body. It is going to be a long, slow, careful process to work out how toxic different make-up recipes might be. It will take months or years.
However, along the way we see results which keep us motivated and excited! We already have glimpses of what we might find. From the data we have, my prediction is that not all white lead make-ups are going to be equally dangerous. Some recipes may be quite benign. Some may be terrifyingly toxic. The answer to the question 'Could a young woman die from her white lead makeup?' may depend on another question: 'What makeup did she wear?'