Exposure to mercury from skin contact or vapor can be challenging to diagnose because of the wide variation in reactions, researchers at the University of Arizona, Tucson, found in the case of a toddler who presented with puzzling symptoms.

“Although mercury toxicity is rare and has variable symptoms, it is valuable for clinicians to consider this diagnosis in cases of unexplained hypertension and neurologic findings,” Michael R. Ori, MD, and his associates wrote in the Journal of Pediatrics.

U.S. federal law has prohibited mercury in cosmetics beyond trace amounts (1 mg/kg) since 1973 because of toxicity concerns, but mercury-containing skin creams remain a public health problem in the United States.

A 17-month-old previously healthy girl was seen by her pediatrician because of a 3-week history of fussiness, constipation, decreased appetite, and temperature to 37.7° C. A chest radiograph was normal, as was a urinalysis. Two days later, the child was taken to the emergency department with symptoms of rhinorrhea, congestion, fussiness, and a fever of 38.3° C. She was sent home with a presumptive diagnosis of a viral syndrome. Her symptoms had not resolved 1 week later, and she returned to the pediatrician, having developed a limp with tenderness in the right knee. A radiograph of the knee was unremarkable, repeat urinalysis showed no evidence of a urinary tract infection, and an abdominal x-ray showed a large stool burden. She had a 0.5-kg weight loss and new hypertension, and was afebrile.

The child was admitted to the hospital the next day for an endocrine work-up, but no noticeable abnormalities were found. She became increasingly fussy with a poor appetite and continued weight loss, persistent hypertension, and an inability to walk. Heavy metal screening on day 18 revealed an elevated whole blood mercury level of 26 mcg/L (normal is less than 10 mcg/L), with a random spot urine mercury level of 243 mcg/g creatinine (normal is less than 35 mcg/g creatinine). Repeated chelation with succimer was provided. On day 61, she had significant delay in receptive language and fine motor skills on a Bayley scale. On the most recent evaluation on day 222, she was shy and had stereotypical hand-flapping behavior when stressed, the investigators reported.

Multiple conversations with the patient’s mother eventually identified the source of mercury as a skin-lightening facial cream she had been using for 4 months, which she stored in the refrigerator. The cream was produced and purchased in a beauty salon in Mexico. Several containers of the cream were sent to an Arizona state laboratory; they were found to have mercury levels between 27,000 and 34,000 mg/kg. The mother and the grandmother had no symptoms or findings on physical exam, but had markedly elevated first-void urine mercury levels of 197 mcg/g creatinine for the mother and 222 mcg/g creatinine for the grandmother, the researchers reported.

Testing of the home the family rented found ambient air mercury vapor levels ranged from 1,900 to 2,800 ng/m3 for most areas. Federal agencies recommend remediation for levels greater than 1,000 ng/m3; remediation was performed in the home, with some household items disposed of in a hazardous waste landfill.

This toddler’s exposure to mercury was from contact with contaminated people, objects, and vapor, although the mercury-containing cream was not directly put on her skin. Of these sources of contact, vapor may have contributed the most. There likely was incidental dermal contact through contaminated bed linens, and she also likely had incidental oral contact from contaminated objects that she put in her mouth, Dr. Ori and his associates reported.

Over time, central nervous system penetration occurs with neurologic dysfunction; “this was the dominant feature of this patient’s presentation, with debilitating leg pain, anorexia, constipation, neurasthenia, and hypertension. Acrodynia, meaning extremity pain, is an idiosyncratic reaction to mercury exposure seen in childhood. Symptoms include irritability,weakness, paresthesias, a pink papular rash, and desquamation of the palms and soles. Our patient did not have the characteristic dermal findings but did have other symptoms consistent with acrodynia,” they noted.

The authors declared no conflicts of interest.

SOURCE: Ori MR et al. J Pediatr. 2018. doi: 10.1016/j.jpeds.2017.12.0.23.