Environmental, Occupational, and Industrial Toxicology
Metals
Lead inhibits ALA dehydratase and ferrochelatase, producing microcytic anemia with basophilic stippling, abdominal colic, and encephalopathy; diagnose with a blood lead level, not hair or urine. Chelate with oral succimer (DMSA) for moderate pediatric levels, or CaNa2EDTA plus dimercaprol for severe or encephalopathic cases - after ending exposure. Arsenic causes gastrointestinal distress, garlic breath, and neuropathy; treat with DMSA or dimercaprol. Mercury exists as elemental vapor, inorganic salt, and organic methylmercury; BAL is contraindicated for inorganic mercury because it may increase brain deposition, so use DMPS or DMSA. Cadmium has no effective chelator; thallium is treated with Prussian blue; iron with deferoxamine.
Pesticides and gases
Organophosphates inhibit acetylcholinesterase, causing SLUDGE plus nicotinic fasciculations and weakness. Titrate atropine to drying secretions (not pupils), give pralidoxime before enzyme aging, and use benzodiazepines for seizures; avoid succinylcholine. Carbamates generally recover without oximes. Carbon monoxide: co-oximetry, 100% oxygen, hyperbaric oxygen for syncope, neurologic signs, pregnancy, or severe COHb; pulse oximetry is falsely normal. Cyanide from smoke or industry: hydroxocobalamin. Methemoglobinemia: chocolate-colored blood, methylene blue 1–2 mg/kg, contraindicated in G6PD deficiency.
Occupational and environmental frameworks
OSHA PELs are enforceable; ACGIH TLVs and BEIs are guidance. Understand exposure pathways, biomonitoring, half-life, bioaccumulation, and the distinction between hazard and risk.
Traps
Chelation does not reverse chronic neurocognitive injury, and chelating before ending exposure can worsen toxicity.
Worked example
A battery recycler with colic and anemia: check blood lead level and zinc protoporphyrin, remove from exposure, and chelate based on level and symptoms.