Summary Statement : The second example concerns chronic mercury toxicity in a child.13 In this 1989 case, a four-year-old child.......

Details : Mercury

The second example concerns chronic mercury toxicity in a child.13 In this 1989 case, a four-year-old child from Michigan presented in a clinician's office with sweating, itching, headaches, difficulty in walking, gingivitis, hypertension, and red discoloration of the palms and the soles of the feet—all symptoms of mercury poisoning. The physician had knowledge of mercury poisoning cases from the earlier part of this century. At that time, medicines and teething powders containing mercury were commonly prescribed for young children. Children who were exposed to large amounts of mercury developed a condition called acrodynia (which means “painful extremities”) weeks or months after exposure. The symptoms of acrodynia include irritability, red discoloration of the hands and feet, pain in joints, heavy sweating, muscle weakness, and difficulty standing or walking. Despite the severity of the effects, it was not until the 1940s that the cause was determined to be mercury poisoning and the use of mercury in medicines for young children was banned. Today it is possible to treat acrodynia, but many physicians are unaware of its existence because it is so rare. This physician, because of his experience, suspected mercury poisoning as the cause of the child's symptoms and began to search for a source of exposure.

The physician reported the symptoms and his suspicion of acrodynia to the Department of Public Health, which found that the mercury exposure came from the painting of the interior of the child's home with latex paint just ten days before the child became ill. At one time, biocides containing mercury were added to about one-fourth of interior latex paints in low concentrations to extend the shelf life of the paint and in higher concentrations to make paints mildew resistant. The paint the family used contained a mercury biocide. After the house was painted, the family slept with the air conditioning system on and the windows closed. The mercury in the paint vaporized, and the child and his family breathed it in. When tested, all members of the family had elevated mercury urine levels; however, only the child was symptomatic. He was hospitalized for four months and received treatments to increase the amount of mercury excreted from the body. After treatment, almost all of the symptoms disappeared, and he could walk again.

There are several reasons the child was more vulnerable to mercury inhalation than the adults in this case. As in the diazinon case, children's higher rate of respiration causes them to take in a greater amount of both air and its contaminants relative to their size than adults (see the article by Bearer in this journal issue). Mercury vapor is also heavier than air, so the area in a room that has the greatest concentration of mercury will be near the floor, where small children play.14

Since 1990, the mercury compound involved has been banned for use in house paints, but this case raises the question of whether there have been a number of instances of similar exposure of children in the recent past that went unrecognized. It also raises a more global question. Chemicals such as mercury were used for many years before their effects became known and their use was banned. How many chemicals currently in use are having other, unknown effects on children? According to the EPA, an estimated three million children each year may have been exposed to mercury through latex paint manufactured before the ban took effect.15 If three million children were exposed to mercury through paint alone, the number exposed to other harmful chemicals in a variety of forms is likely to be much greater.