Occupational toxicology & industrial hygiene

OSHA PELs, NIOSH RELs, IDLH values, and the meaning of TWA, STEL, ceiling ('C') limits, and the Skin notation; how exposure limits are derived, computed (mixtures, extended shifts), and applied through the hierarchy of controls. Emphasis on interpreting and applying limits and notations — not memorizing specific values from Tables Z-1/Z-2/Z-3.

Elimination, substitution, engineering and administrative controls, and PPE; respirator selection, assigned protection factors, and fit testing (29 CFR 1910.134). General PPE program requirements (29 CFR 1910.132): the workplace hazard assessment and its written certification, PPE selection and proper fit, employee training (when and what PPE is necessary, donning/doffing and adjustment, the limitations of the PPE, and its care and maintenance) and retraining triggers, the prohibition on defective equipment, employee-owned equipment, and employer payment for PPE including the exceptions (non-specialty safety-toe footwear and prescription eyewear, and everyday clothing).

Air-sampling strategy, analytical methods, exposure assessment, and interpretation of monitoring data.

Inorganic lead toxicology, clinical effects, and OSHA medical surveillance. Toxicokinetics: absorption, distribution to bone (long-term reservoir) and soft tissue, biological half-life, and blood lead level (BLL) as the key biomarker. Hematological effects of heme synthesis disruption: ALA-dehydratase and ferrochelatase inhibition, zinc protoporphyrin (ZPP) elevation, basophilic stippling, microcytic anemia. Neurological effects: peripheral motor neuropathy (wrist drop), encephalopathy in severe exposure, neurodevelopmental effects in children. Renal effects: chronic nephropathy and saturnine gout. Reproductive and developmental risks. Chelation therapy (EDTA, succimer/DMSA). Surveillance, biological monitoring, and medical removal protection under 29 CFR 1910.1025.

Occupational mercury and arsenic toxicology. Mercury: chemical forms (elemental vapor, inorganic salts, methylmercury), neurological effects (tremor, erethism), nephrotoxicity, biomarkers, chelation. Arsenic: occupational exposure (smelting, semiconductor), dermatologic findings (hyperkeratosis, Mees lines), peripheral neuropathy, and arsenic-related cancers.

Benzene (hematotoxicity, leukemia), toluene, and related solvents; CNS, hepatic, and hematologic effects and their monitoring.

Carbon monoxide poisoning in occupational and environmental settings. Carboxyhemoglobin (COHb) measurement and interpretation, including its limitations as a severity marker after oxygen therapy. Hyperbaric versus normobaric oxygen therapy: indications, timing, and the effect on carbon monoxide elimination kinetics. Delayed neuropsychiatric sequelae and their time course. Cardiovascular effects in workers with coronary artery disease. Fetal and maternal carbon monoxide toxicokinetics in pregnant workers. Carbon monoxide and cyanide co-exposure in smoke inhalation. Altitude and endogenous carbon monoxide. Sources of occupational carbon monoxide exposure.

Chemical asphyxiants other than carbon monoxide: hydrogen sulfide and cyanide. Hydrogen sulfide: the knockdown effect, cytochrome oxidase inhibition, carotid body stimulation and respiratory arrest, nitrite treatment, and long-term neurologic sequelae. Cyanide: cellular mechanism of toxicity, lactic acidosis and elevated venous oxygen saturation, retinal arterialization, antidotes (hydroxocobalamin, sodium thiosulfate, nitrites), fire-gas exposure, and the bitter almond odor.

Organophosphate and carbamate insecticides, the cholinergic toxidrome, cholinesterase monitoring, and management.