Skin uptake of polycyclic aromatic compounds at occupational exposure: PAHs and their nitro- and oxy-derivatives, underlying genetic factors and risk assessment of exposure

Exposure to toxic and carcinogenic chemicals in the work environment occurs in many occupations.

Examples of such chemicals are polycyclic aromatic hydrocarbons (PACs) such as polycyclic aromatic hydrocarbons (PAHs) and their derivatives.

Occupational groups that may be highly exposed to PACs are smelters, chimney sweeps, asphalt workers, seafarers, and firefighters.

Traditionally, exposure via inhalation has been studied, but uptake through the skin may be more extensive in some professions.

Knowledge about the extent of skin uptake of PACs is limited and this underlines the importance of clarifying exposure to toxic and, above all, carcinogenic PACs via the skin.The aim of this project is to investigate personal exposure to PACs through skin absorption in a controlled study of firefighters during smoke diving.

The study design enables the isolated investigation of skin exposure, as the inhalation route is excluded by the respiratory protection (breathing apparatus). Nitro- and oxy- derivatives of PAHs are present together with parent PAHs in fire gases.

These PAH derivatives can be more toxic than parent PAHs and new research shows that they can contribute significantly to the cancer risk at PAH exposure.

The highly toxic nitro-PAH and oxy-PAH, as opposite to parent PAH, are neither regulated nor routinely monitored, and have not previously been assessed with respect to dermal uptake in occupational settings.The main purpose of the project is to study exposure through skin uptake for many PACs with a special focus on nitro- and oxy-PAH in work environments.

We will examine 100 firefighters and analyze different PACs in air, skin and urine samples before and after smoke diving.

Furthermore, the project aims to: 1) identify underlying factors, such as individual sensitivity (genetic variation of the filaggrin gene) that may affect the degree of absorption of chemicals through the skin; 2) assess the health risks associated with the exposure based on existing guideline levels and reference doses; 3) explore a passive sampler that will mimic skin uptake of PACs and visualize skin uptake of PACs by means of mass spectrometry imaging.The project will lead to suggestions for improvement and safety measures to minimize exposure and thus health risks due to the uptake of number of PACs including the toxic nitro- and oxy-PAH classes through the skin.

The results will be applicable to other occupational categories with a risk of increased exposure to PACs.