This child has had a significant exposure to a skin-lightening agent, which in this case contained high levels of mercury. Although the sale of these products is illegal in the U.S., many have ready access to non-regulated products brought from overseas or bought online.
Mercury exposure may be from elemental (thermometers, thermostats), inorganic (cosmetics), and organic (methylmercury: seafood; ethylmercury: preservative) sources. Route of exposure includes inhalation (especially inadvertently heated elemental forms), ingestion, transdermal, and injection. The mercury toxidrome may differ by source and chronicity of exposure. In general, CNS and renal sequelae predominate (irritability / depression / fatigue / memory loss / tremor; nephrotic syndrome). If inhaled (as in vaporization from heated elemental mercury: e.g. well intentioned “clean-up” by vacuum cleaner, which heats the mercury and vaporizes it to the environs), it may cause a fatal interstitial pneumonitis.
In adults, mercury toxicity is often due to chronic exposure; dermal absorption is related to the concentration of the compound, and the long half-life of Hg+1 (1-2 months) puts the user at risk for steadily accumulating up to toxic levels.
In children in the modern era, presentation may be due to acute or chronic exposure (some products used by curanderos, Eastern herbal practitioners, and other traditional healers may also pose a chronic exposure). A particular pediatric presentation is acrodynia (Gr: “painful extremities”), also called pink disease. Children may present with behavioral changes such as aggressiveness, irritability, lethargy or weepiness. Photophobia, pink discoloration and edema to the hands and feet, polyneuritis, diaphoresis, tachycardia, hypertension, poor muscle tone, and diarrhea may also be seen.
In both adults and children, an acute presentation is metal fume fever: vaporized mercury can cause weakness, fever, chills, fatigue, headache, abdominal pain, and dysuria. This highlights the importance of eliciting a good occupational or environmental exposure from patients with vague, non-focal symptomatology or unexplained flu-like symptoms.
Early chelation (B) is the cornerstone of treatment. DMSA forms water-soluble chelates with heavy metals and is excreted by the kidneys (other options include BAL and penicillamine). Consultation with Poison Control or a toxicologist is recommended, especially in the context of this uncommon, high-risk condition that may present subtly initially.
Urinary alkalinization (A) is used in aspirin toxicity. A careful history is important to exclude the possibility of exposure to methyl salicylate cream, as even a small ingestion may be fatal to a child.
In general, in trivial or unknown exposures without symptoms, it is common to observe for four hours (C). In this case, however, the exposure is high-risk, and arguably presenting with early signs (drooling and erythema of lips). The child in this case soon developed swelling of the lips and cheeks without respiratory signs. Early chelation was started, he was admitted, and three days later he developed non-oliguric renal failure. He recovered completely after a week of treatment.
Upper endoscopy is important in the management of alkali exposures that cause esophageal corrosion and subsequent strictures (D). Although endoscopy may be indicated non-emergently in this child, the important intervention here is early chelation.
For the World Health Organization Executive Summary, see link:
For your homework: do a casual search of “Minamata Bay” and “mercury”