The physical examination may not be helpful in determining if an exposure occurred. Rashes need to be carefully described and secondary changes due to scratching, infection, or treatment documented. Halogenated hydrocarbons can produce chloracne that may be confused with acne vulgaris in adolescents. Anhydrous ammonia can cause a characteristic hyperpigmented area after a burn heals. Petroleum products may cause irritative dermatitis. Scabies is common among farm workers. Allergic contact dermatitis may have a variety of causative agents (Table 13.3) (1,13).
Inhalation of dusts, mists, and gases may cause instantaneous or delayed bronchospasms, producing a constellation of symptoms from wheezing to respiratory collapse. Nausea, vomiting, diarrhea, and abdominal pain can be the result of chemical exposure or from alternate illnesses such as diabetes, food poisoning, or influenza. Food poisoning is common in people who work in the fields and do not have the facilities to refrigerate their lunches. Anaphylaxis can result from envenomation by biting or stinging insects (9,14).
Neurological symptoms such as burning, numbness, tingling, twitching, or seizures may be immediate or can be a delayed result of exposures. For example, low-level chronic exposure to organophosphates can cause a delayed polyneuropathy or memory loss (15).
Ocular symptoms are common in persons exposed to powders, dusts, sprays, or mists. After decontamination, the sclera may be erythemic. The corneas must be carefully examined for clouding or opacities.
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