Awareness and control of allergenic chemicals (1)

In modern society, people have lived in a world where chemical substances are ubiquitous.

Allergic reactions to chemical sensitizers can occur in parts of the body where there are mucosa and subcutaneous connective tissue

Figure 19-2 Skin allergic reactions on various parts of the human body

1.

Chemicals that can directly or indirectly cause allergic reactions are called sensitizing chemicals

As a hapten or simple hapten, a small molecular weight sensitizing chemical substance cannot cause the production of specific antibodies or sensitized lymphocytes in the body by itself, but it can react with specific antibodies or sensitized lymphocytes, that is, these compounds have antigens on their molecules.

The ability of a chemical substance as a hapten or simple hapten to bind to a protein is closely related to certain active groups in the chemical structure of the substance.

Table 19-1 Active groups that are easy to bind to proteins

(1) Animal sensitization test standards

Skin sensitization/allergic contact dermatitis refers to the immune-derived skin reaction of the skin to a substance.

Just like the evaluation of the toxicity of chemical substances, the toxicity of chemical substances is not distinguished by toxic or non-toxic, but LD ₅₀ , LC ₅₀ and other test data are used to illustrate the magnitude of its toxicity

Table 19-2 is based on the above-mentioned national standard methods and artificially analyzed the results of animal quantitative control experiments

Table 19-2 Classification of sensitization intensity of chemical substances

(2) The sensitization route of animal testing

The immunological mechanism of chemical sensitizer allergy includes humoral immunity and cellular immunity

1.

The transdermal sensitization test is mainly used to determine the effect of skin contact chemical sensitizers

2.

Conjunctival sac, nasal cavity and other mucosal instillation methods are mainly used to determine the sensitization of chemical sensitizers that may come into contact with the mucous membranes

3.
Intradermal injection

The intradermal injection method has accurate dosage, convenient operation and management, and sensitive reaction.
It is mainly used to determine the inherent sensitization of chemical substances, and is suitable for chemical substances that can come into contact with the human body through a variety of ways
.

The sensitization methods of delayed allergy experiments, from the perspective of the route of poisoning, have been reported successfully for percutaneous application, intradermal injection, intraperitoneal injection, intralymph node injection and inhalation
.

Different sensitization pathways have a certain impact on the quality and quantity of allergies
.
It is generally believed that intradermal injection and skin application have a higher sensitization rate for delayed allergy
.

Delayed type allergy is the most common type of allergy caused by chemical substances, but the consequences are not the most serious, while immediate type allergy, especially anaphylactic shock, can cause serious consequences, although the probability of occurrence is much longer than that of late The hair>
.

4.
Sensitization positive control substance

The positive controls for skin sensitization tests used in national standards are listed in Table 19-3
.

Table 19-3 Positive Control