PRINCIPLES OF TOXICOLOGY

200 IMMUNOTOXICITY: TOXIC EFFECTS ON THE IMMUNE SYSTEM
TABLE 10.4 Examples of Agents that Produce Dermal Contact Sensitivity
Drugs Metals
Benzocaine Beryllium
Thimerosal Cadmium
Neomycin Chromates
Resins Gold
Acrylic resins Mercury
Epoxy resins Nickel
Formaldehyde resins Silver
Phenolic resins Zirconium
Other industrial chemicals
Ethylenediamine
Paraphenylenediamine and other dyes
Antioxidants
Chlorinated hydrocarbons
Dinitrochlorobenzene
Me rcaptans
IgE-mediated. Table 10.5 lists examples of common agents associated with respiratory allergy.
Occupational asthma represents a special kind of inhalation disorder that is distinct from typical
respiratory allergy. In general, a longer sensitization period is required, and symptoms may resemble
an early-phase reaction, a late-phase reaction, or both. IgE may be responsible for some, but not all,
of the manifestations of occupational asthma. In fact, the role of the immune system in occupational
asthma may be different for asthma initiated or provoked by high-molecular-weight compounds,
low-molecular-weight compounds, and irritatants.
The potential for immunosuppression from occupational and environmental exposure to
chemicals has been suggested by numerous in vitro studies and experiments in laboratory animals.
Direct evidence for clinical immunosuppression following workplace or environmental exposures
is extremely limited. However, there are many well-documented examples of the development or
exacerbation of autoimmunity from chemical exposure. Most of these examples (shown in Table
10.6) are drugs, and for agents such as procainamide, up to 80 percent of patients treated
chronically will develop increased levels of autoimmune antibodies. Many of these drugs produce
signs and symptoms resembling systemic lupus erythematosus, while others produce autoimmune
disease of the kidney, liver, thyroid, and other organs; scleroderma; or autoimmune hemolytic
anemia. Evidence suggests that several environmental contaminants may also have the ability to
either produce or worsen autoimmune disease, although the association with autoimmune disease
is often less well substantiated.
TABLE 10.5 Examples of Agents that Product Respiratory Allergy
Molds Dusts and Small Particulates
Aspergillus Coffe e
Cladosporum Enzymes
Hormodendrum Flour
Penicillium Mites
Rhizopus Sawdust
Pollens (various) Pet dander
Cockroach proteins