A battery manufacturing plant worker presents with wrist drop (extensor weakness), basophilic stippling of red blood cells, and elevated blood lead level of 55 µg/dL. According to NIOSH/BEI guidelines, chelation therapy should be initiated when blood lead level in adults exceeds:

• A 25 µg/dL
• B 70 µg/dL
• C 60 µg/dL
• D 45 µg/dL ✓

Explanation

The threshold for initiating chelation therapy (DMSA or CaNa₂EDTA) in adults with occupational lead poisoning is blood lead level ≥ 45 µg/dL according to standard guidelines. Removal from exposure is recommended when BLL exceeds 30 µg/dL; chelation begins at ≥ 45 µg/dL symptomatic or ≥ 70 µg/dL regardless of symptoms in some guidelines, but 45 µg/dL is the key threshold for initiation of treatment in symptomatic adults. In children, the threshold for chelation is much lower (≥ 45 µg/dL for DMSA; hospitalization considered ≥ 70 µg/dL). Wrist drop reflects peripheral motor neuropathy from lead affecting demyelination in motor nerves.

Reference: Park's Textbook of Preventive and Social Medicine, 27th ed.

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Written and medically reviewed by the StethoPrep medical team.