Employers are required to inform workers of the hazards of the chemicals or products that they are using. Many in vitro assays are suited to accomplish this goal. As Hazard Communication is now aligned with the Globally Harmonized System (GHS), assays that are approved for assigning GHS hazard categories can provide a method for properly labelling chemicals and preparing safety data sheets.
Skin Corrosion assays (Reconstructed Human Epidermis (OECD TG 431) and Membrane Barrier Test (OECD TG 435)) can be used to classify as a GHS category 1 or non-corrosive material, and may also allow for sub classification into categories 1A, 1B, or 1C. Skin irritation can also be evaluated using the reconstructed human epidermis for classification of GHS category 2 (OECD TG 439).
Two assays have been approved for assessing skin sensitization (OECD TG 442C and 442D) and evaluate different actions in the sensitization adverse outcome pathway to predict if a material is a sensitizer. Ocular irritation can be assessed by assigning a GHS No Category or Category 1 classification using either the Bovine Corneal Opacity and Permeability (BCOP) Assay (OECD 437), or the Eye Irritation Test using the Reconstructed Human Cornea-like Epithelium (OECD TG 492). Together, these assays can provide information needed to ensure that employees are properly protecting themselves from the chemicals used in their daily operations.
Although hazard assessment may be the primary goal for occupational safety, assays can be customized to meet client needs for their internal safety evaluations. If the user is more concerned with actual exposure conditions, then testing the neat materials for hazard assessment may give an over-prediction for the potential exposure risk. When modifying approaches to validated protocols, reference materials of know irritancy can provide valuable information on the safety of new formulations.
A reference material should be similar in product class to the new material being tested and have existing in vivo, clinical, or consumer response data. The results can then be compared to the reference material to determine if the new product is less toxic, comparable, or more toxic. Although not officially validated, additional assays such as the Time-To-Toxicity assays for ocular or dermal irritation, as well as the Corrosion/Irritation Hybrid Assay can be used in internal safety evaluations to provide additional information on the toxicity profile of the test article, which may not be possible when following some of the OECD test guidelines.