MITRA Forum Question Details

I will solicit some responses for this because it is super important to get this right. I do want to mention that very small differences in molecules can have a massive impact on toxicity as well as other characteristics. Carbon dioxide and carbon monoxide being a very well-known example. Lead nitrite (and lead acetate) are freely soluble in water unlike lead carbonate so this may be an apples to oranges analogy.

This is in no way to state that PW1 is not without handling concerns. Inhalation being the most important. Again, we will get experts to weigh in on whether this or other common pigments can trans-dermally enter the blood stream.

I am going to let the experts comment on whether solvents enhanced trans-dermal effects.

​I am also interested in learning more about this topic. A few years ago, I read that blood tests did not immediately reveal elevated levels when lead was absorbed through skin, and also that the type of soap/detergent used for cleanup could impact rate of uptake. I know there are special soaps for cleanup after handling lead ammunition.

I am not a toxicologist, but have done much research on the toxicology of the lead, mercury and arsenic-based pigments in paint.

Absorption of substances through the skin depends on a number of factors, the most important of which are concentration, duration of contact, solubility, molecular weight of the substance, and physical condition of the skin and part of the body exposed.

Chemicals must pass through the seven cell layers of epidermis before entering the dermis where they can enter the blood stream or lymph and circulate to other areas of the body. The outermost layer of the epidermis is the rate-limiting barrier in absorption. Thus, how quickly something passes through this thicker outer layer determines the overall absorption. If the skin is in healthy condition, substances that are not soluble in lipds and water are less likely to pass through this outer layer due to diffusion.

Basic lead carbonate or lead white is essentially insoluble in water (0.00011 g/100 mL at 20 °C) and lipids, so the risk of asborption through the skin is small. When the pigment is in oil paint, it is less likely to be absorbed through the skin due to the lower concentration and potential contact.

Other pigments mentioned do not pose a significant health risk by skin absorption because these pigments are also insoluble in water and lipids.

Certain solvents like dimethyl sulfoxide (DMSO) can act as carriers and are frequently used to transport medication through the skin. DMSO increases the permeability of the skin. Surfactants like sodium lauryl sulfate found in cleaning and washing products increase the skin penetration of water-soluble substances, possibly by increasing the skin permeability of water.

The presence of acids on the skin may also increase the likelihood of absorption because certain mineral and organic acids can convert lead white to soluble lead substances.

Of course, the best practice is to wear gloves while painting or handling all pigments and paint products to avoid personal exposure altogther.