In Vitro Skin Irritation, Corrosion, and Sensitization Testing

Irritation and corrosion testing uses 3D human skin models (EpiDerm™ and EpiSkin®). In addition, an in chemico assay, Corrositex®, can be used to assign skin corrosion classifications. 

Besides the established models, Charles River is also involved in optimizing-skin irritation and corrosion testing for formulations by developing new models using full-thickness human skin models.

Skin sensitization is a hypersensitivity reaction resulting from the interaction of a sensitizing agent with host proteins to form an immunogenic complex. Examples of sensitizers include para-phenylenediamine (PPD) in hair dyes and nickel in clothes or jewelry. When these small molecules (haptens) bind to proteins, they become immunogenic and activate the immune system, which causes localized inflammation at the site of sensitizing agent exposure. We offer a complete portfolio (OECD 497: defined approaches on skin sensitization) including in silico, in chemico, in vitro, and in vivo options, in addition to regulatory support.

While regulatory acceptance of in vitro alternatives in a tiered approach continues to grow, in vitro skin assays are also a valuable tool for screening ahead of in vivo testing.

As part of our integrated toxicology testing strategy, there may be cases where the in vivo test should still be performed rather than the in vitro test or where an in vivo test is required as follow up test. For example, the in vivo test should be used when a classification cannot be assigned or where a regulatory authority specifically requires in vivo data.

Scientific Publications

In Vitro Skin Assays

SKIN IRRITATION ASSAYS 

  • SkinEthic Reconstructed Human Epidermis (OECD 439)
  • Mattek Epiderm Skin Irritation Test (OECD 439)
  • Phenion® Full Thickness Human Skin Model
  • Dermal Acute Nonrodent
  • Acute Dermal Rodent

SKIN CORROSION ASSAYS

  • SkinEthic EpiSkin® Skin Corrosion (OECD 431)
  • Mattek Epiderm Skin Corrosion Test (OECD 431)
  • Corrositex® Skin Corrosion (OECD 435)

SKIN SENSITIZATION ASSAYS

Choose your assay

Frequently Asked Questions (FAQ) for Skin Irritation and Corrosion Testing

  • What methods are used in skin irritation testing?

    There are two broad categories of tests for skin irritation used in safety assessment for drug development: in vivo (using animals) and in vitro (using human relevant models). Each has its advantages and limitations. A comparative analysis of skin morphology shows significant anatomical and functional differences between rabbits, rodents and humans that have effect on the accuracy of the tests using rabbit or rodent skin for predicting human health outcomes. Therefore, several human relevant in vitro models are now available.

    In vivo skin irritation tests

    Draize test: This historically common test, now being phased out due to ethical concerns, uses animals to directly apply the test substance to their shaved and abraded skin. Followed by subjective evaluating and scoring of the severity of the damage.

    Modified Draize test: This uses similar principles to the Draize test but reduces the amount of test substance applied and uses scoring systems to refine the assessment of irritation.

    In vitro skin irritation tests

    Skin Irritation Test (SIT) in a Reconstructed Human Epidermis (RhE) Model
    Skin Irritation in the regulatory hazard classification and labeling context is defined as the production of reversible damage to skin following a defined chemical exposure. The Skin Irritation Test (SIT) is an in vitro, test using human cells designed to identify those chemicals and mixtures capable of inducing moderate skin irritation (UN GHS Category 2 Skin Irritants*), as well as those not requiring classification for skin irritation potential. This test method is useful for regulatory classification and labeling of chemicals and mixtures, and depending upon the regulatory jurisdiction and framework the test results may be used as standalone or to support a weight of evidence approach.

    *United Nations (UN) Globally Harmonized System (GHS) of Classification and Labelling of Chemicals

    Skin Irritation Test (SIT) in a Reconstructed Human Full Thickness Skin Models
    Human Full thickness skin models like the Phenion ® FT skin model consists of both a fully differentiated epidermis, the outermost layer of the skin, and the underlying dermis that contains a natural, collagen-based connective tissue. In consequence, the model resembles human native skin in a variety of anatomical and physiological properties, making it an ideal tool for research projects as well as for the development of innovative, replacement test methods. The barrier function of these full thickness models is similar to the human skin, resulting in human relevant results for formulations like antimicrobial cleaning products (https://doi.org/10.1016/j.tiv.2023.105726)

  • What is skin irritation animal testing?

    Skin irritation animal testing refers to methods used to assess the potential of a substance to cause harm to the skin by applying it directly to live animals, most commonly rabbits. These tests, while historically widespread, are facing increasing ethical scrutiny and being replaced by alternative non-animal human relevant methods whenever possible.

    Here's how skin irritation animal testing typically works:

    • Preparation: The animal is shaved and sometimes abraded on a small area of the back.
    • Application: The test substance is applied to the prepared skin, often covered with a patch to keep it in contact.
    • Observation: The animal is monitored for a set period, typically several days, for signs of irritation. These can include redness, swelling, and blistering.
    • Scoring: The severity of the observed effects is scored according to a standardized system to determine the level of skin irritation caused by the substance.