• Irritability
• Abdominal pain
• Ataxia
• Seizures/loss of consciousness
• (Chronic) learning deficits
• Hyperactivity, reduced attention span

Key Signs/symptoms of Mercury Poisoning

• Muscle cramps or tremors
• Headache
• Tachycardia
• Intermittent fever
• Acrodynia
• Personality change
• Neurological dysfunction

Diagnostic Leads

• Does the family reside in old or restored housing?
• Has renovation work been conducted in the home, workplace, school, or day care facility?
• Is the home located near a busy highway or industrial area?
• Does the individual work with lead materials such as solder or automobile radiators?
• Does the child have sibling, friend, or classmate recently diagnosed with lead poisoning?
• Has the individual engaged in art, craft, or workshop pursuits?
• Does the individual regularly handle firearms?
• Has the home interior recently been painted with latex paint that may contain mercury?
• Does the individual use mercury in religious or cultural activities?

Remedial Action

Wet-mop and wipe furniture frequently to control lead dust. Have professional remove or encapsulate lead containing paint; individuals involved in this and other high-exposure activities should use appropriate protective gear and work in well-ventilated areas. Do not burn painted or treated wood.

Comment

Airborne Lead

Most health professionals are aware of the threat of lead toxicity, particularly its long term impact on children in the form of cognitive and development deficits which are often cumulative and subtle. Such deficits may persist into adulthood.⁴⁸ According to the American Academy of Pediatrics, and estimated three to four million children in the U.S. under age six have blood lead levels that could cause impaired development, and an additional 400,000 fetuses are at similar risk.⁴⁹

Lead toxicity may alternatively present as acute illness. Signs and symptoms in children may include irritability, abdominal pain, emesis, marked ataxia, and seizures or loss of consciousness. In adults, diffuse complaints-including headache, nausea, anorexia (and weight loss), constipation, fatigue, personality changes, and hearing loss-coupled with exposure opportunity may lead to suspicion of lead poisoning.

Lead inhibits heme synthesis. Since interruption of that process produces protoporphyrin accumulation at the cellular level, the standard screening method is investigation of blood lead (PbB) levels which reveal recent exposure to lead. Acute symptomology in adults is often associated with PbB at levels of 40 µg/dl or higher. There is good evidence for adverse effects of lead in very young children at much lower levels.^{50, 51} The Centers for Disease Control and Prevention has set 10 µg/dl as the level of concern.⁵² Increased maternal Pb exposure has also been deemed significant in pregnancy, since an umbilical cord PbB of greater than 10 µg/dl has been correlated with early developmental deficits. If sufficiently high PbB levels are confirmed, chelation therapy may be indicated. Suspected low level lead contamination cannot be accurately identified by a erythrocyte protoporphyrin (EP) finger-stick test, but requires blood lead analysis.

Lead poisoning via ingestion has been most widely publicized, stressing the roles played by nibbling of flaking paint by infants and toddlers and by the use of lead-contain foodware (glass, and soldered metal-ceramic ware) by adults. Lead dust flaking or "chalking" off lead painted walls generated by friction surfaces is a major concern. Airborne lead, however, is also a worrisome source of toxicity. There is no skin absorption associated with inorganic lead.

Airborne lead outdoors, originating chiefly from gasoline additives, has been effectively controlled since the 1980s through regulation at the federal level. Much of this lead still remains in the soil near heavily trafficked highways and in urban area, however, and can become airborne at times. It may enter dwellings via windows and doors, and contaminated soil can also be tracked inside.

Indoors, the chief source is paint. Lead levels in paints for interior use have been increasingly restricted since the 1950s, any many paints are now virtually lead free. But older housing and furniture may still be coated with leaded paint, sometimes surfacing only after layers of later, non-lead paint have flaked away or have been stripped away in the course of restoration or renovation. In these circumstances, lead dust and fumes can permeate the air breathed by both adults and children.

Additional sources of airborne lead include art and craft materials from which lead is not banned, but the U.S. Consumer Product Safety Commission (CPSC) requires its presence to be declared on the product label if is it present in toxic amounts. Significant quantities are found in many paints and glazes, stained glass, as well as in some solder. Hazardous levels of atmospheric lead have been found at police and civilian firing ranges. Repair and cleaning of automobile radiators in inadequately ventilated premises can expose workers to perilous levels of airborne lead. The use of treated or painted wood in fireplaces or improperly vented wood stoves may release a variety of substances, including lead and other heavy metals, into the air.

Mercury Vapor

While old paint has been the most publicized source of airborne heavy metal (i.e., lead), new paint as emerged as a concern as well. A 1990 report detailed elevated levels of mercury in persons exposed to interior latex (water-based) paint containing phenylmercuric acetate.⁵³ PMA was a preservative that was used to prolong the product's shelf life.

Initial action the U.S. Environmental Protection Agency results in the elimination of mercury compounds from indoor latex paints at the point of manufacture as of August 1990, with the requirement that paints containing mercury, including existing stocks originally designed for indoor use, be labeled or relabeled "For Exterior Use Only." As of September 1991, phenylmercuric acetate is forbidden in the manufacture of exterior latex pains as well. Latex paints containing hazardous levels of mercury may still remain on store shelves or in homes where they were left over after initial use, however.

An additional matter of concern, recently noted by the CPSC, is the sprinkling of mercury about the home by some ethnic/religious group.⁵⁴ According to the CPSC mercury for this purpose is purveyed by some herbal medicine or botanical shops to consumers unaware of the dangers of the substance.

References

48  Needleman, H.L., Schell, A. et al. "The Long-Term Effects of Exposure to Low doses of Lead in Childhood: An 11-Year Follow-up Report." The New England Journal of Medicine 1990; 322:83-88.
49  American Academy of Pediatrics. "Lead Poisoning: Next Focus of Environmental Action." Statement issued January 1991.
50  Bellinger, D., Sloman, J. et al. "Low-Level Lead Exposure and Children's Cognitive Function in the preschool Years." Pediatrics 1991; 87:219-27.
51  "Lower 'Threshold of Concern' for Children's Lead Levels." FDA Consumer, December 1991, p. 6.
52  Centers for Disease Control. "Preventing Lead Poisoning in Young Children." October 1991.
53  Agocs, Mary M., Etzel, Ruth A. et al. "Mercury Exposure from Latex Interior Paint." The New England Journal of Medicine, 1990; 323:1096-1101.
54  Consumer Product Safety Commission. Safety Alert: Mercury Vapors.