Agency for Toxic Substances and Disease Registry
Case Studies in Environmental Medicine (CSEM) 

Pediatric Environmental Health
Case Study (Continued)

Case Study (Continued)

In the hospital, you make a working diagnosis of mercury poisoning and consult with a pediatric environmental medicine specialist. You determine that this is a case of acrodynia. The child is treated. In this case of acrodynia, succimer (2,3-dimercaptosuccinic acid [DMSA]) is administered orally in three daily dosages. DMSA is dispensed in 100-milligram (mg) capsules that can easily be opened, allowing the drug to be mixed with a food product (e.g., applesauce) if necessary. This treatment is continued for several days; urine mercury excretion peaks shortly after introducing the chelation treatment. Clinical reassessment and urine mercury excretion are measured on day 7 of treatment. Urine mercury levels are still elevated and treatment is resumed at a lower dosage for 5 more days, during which the child's mood and rash begin to improve. He is completely asymptomatic the next week, and has no elevation in urine mercury excretion.

Appendix B includes further information regarding the treatment of elemental mercury poisoning.

Note: Chelation has been used to reduce body burden of elemental mercury; however, whether it reduces toxic effects or speeds recovery in mercury-poisoned children remains unclear (Etzel 2001). Chelation should only be used for symptomatic patients with known mercury exposure, and only after consideration of the risk and benefits by a specialist experienced in the use of chelators and in consultation with the patient or family.

An investigation reveals that the mercury thermometer factory employees (including the child's father) change their clothing after working with mercury, but that most do not change their shoes. You also find out that the teenagers who took the elemental mercury from the local high school chemistry lab were questioned and evaluated. The elemental mercury was retrieved and environmental testing of possible points of exposure was completed. One of the teenagers who had been doing odd jobs at the patient's home admitted spilling mercury in the child's room on the carpet. She tried to clean up what she could see with a paper towel, then flushed it down the toilet. In addition to mercury contamination in the patient's home, more than a dozen other homes, several cars, shops, schools, and recreational areas in the community have also been contaminated. A surveillance program finds that urine mercury levels in the thermometer factory workers, their spouses, and adults not associated with the thermometer factory do not exceed levels of public health concern, but that elevated levels were found in a few young children whose homes and family cars were contaminated. These children have been followed up with pediatric environmental medicine expert consultation. In addition, the state division of environmental protection has been addressing the environmental contamination issues.

The environment is remediated before the child returns to his home (the carpet is replaced [Goldman et al. 2001] and follow-up testing of elemental mercury levels in the home within acceptable limits). The father changes his work clothes and shoes before coming home from work. The state division of environmental protection is also addressing any possible source of mercury from when the building in which the family lives was used for commercial activities (as a jewelry factory complex) and whether mercury might be continuing to undergo subsequent volatilization. Whether the elevated urinary mercury level and acrodynia in this child is due to the take-home exposures, the jewelry factory complex, or the spill in his room, all possible exposure pathways have been mitigated.

This case study addresses a situation where a high index of suspicion for an environmental cause of disease is warranted. However, different types of office visits-a well child coming in for routine care, a child coming in for an illness that might be related to an environmental exposure, or a child with a known or suspected exposure (with or without symptoms)-would call for different evaluative approaches. In any of these scenarios, however, a pediatrician or other child health care provider can integrate environmental health issues into practice. This integration will be explored later in the text.

In addition to mercury, children might be exposed to a variety of environmental toxicants encountered in indoor and outdoor environments of the home, child care setting, school, or workplace (including take-home exposures). Children might also be exposed to out-of-home pollutants, including those found in hazardous waste sites. About 15,000 uncontrolled hazardous waste sites exist throughout the United States, with 1,508 sites proposed or listed on the National Priorities List (NPL). ATSDR has used geographic information systems to estimate the number of children living near NPL sites. On the basis of data from 1,255 sites, 1,127,563 children <6 years of age live within 1 mile of the sites (about 11% of the potentially affected population), although it is important to realize that proximity alone does not mean that exposure will occur.

Challenge

1. What is the likely explanation for this apparent pattern of mercury exposure?
2. What agencies might help you assess the nature and extent of this problem, and what procedures can help confirm the source of the mercury exposure?
3. You call local public health officials to discuss the case. You are asked your thoughts about the case. They ask whether you suspect that others have been exposed. What is your answer?
4. How do you explain the finding of high urine mercury levels in the child, but normal levels in other household members?
5. The wife of another thermometer factory worker is breastfeeding her newborn infant. She is concerned that her breast milk might be exposing the infant to mercury. How would you advise her?
6. A neighbor's teenage son plans to work this summer as an errand boy and custodian at the thermometer factory. His father hears about your patient's recent mercury exposure and calls to ask for your advice. Are there any special dangers to an adolescent working on the production floor of the factory? How would you advise him?

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