Environmental Medicine Integrating a Missing Element into Medical Education (1995) / Chapter Skim
Currently Skimming:
Case Study 19: Lead Toxicity
Case Study 19: Lead Toxicity
Pages 410-435
The Chapter Skim interface presents what we've algorithmically identified as the most significant single chunk of text within every page in the chapter.
Select key terms on the right to highlight them within pages of the chapter.
From page 410... ...
In ad~ifion to renal disease, cardiovascular effects, and reproductive toxicity, lead may cause irreversible necrologic damage. Blood lead levels once considered safe are now considered hazardous, with no known fresher Ed Lead poisoning is a wholly preventable disease.
|
From page 411... ...
The diagnosis was "mild iron deficiency anemia," and iron therapy was prescribed. The family failed to keep several follow-up appointments, but the child did apparently complete the prescribed 3-month course of iron supplements.
|
From page 412... ...
No economic or racial subgroup of children is free from the risk of having blood lead levels high enough to cause adverse health effects. In 1984, approximately 17% of children in the United States were estimated to be at risk of lead poisoning.
|
From page 413... ...
ch~a~en~reJP~ (1) Who else in the family or community discussed in the case study is at risk of lead poisoning?
|
From page 414... ...
High levels of lead in soil and house dust have been associated with increased blood lead levels in children. Food may contain lead from the environment or from containers.
|
From page 415... ...
In 1976 and in 1984, federal regulation drastically reduced the amount of lead in gasoline, and today organic lead in gasoline is not as great an environmental concern in the United States as it is in other countries, where it remains a serious hazard. Sources of lead exposure Occupational Plumbers, pipe fitters Lead miners Auto repairers Glass manufacturers Shipbuilders Printers Plastic manufacturers Lead smelters and refiners Police officers Steel welders or cutters Construction workers Rubber product manufacturers Gas station attendants Battery manufacturers Bridge reconstruction workers Firing range instructors Environmental Lead-containing paint Soil/dust near lead industries, roadways, lead-painted homes Plumbing leachate Ceramicware Leaded gasoline Hobbies and Related Activities Glazed pottery making Target shooting at firing ranges Lead soldering (e.g., electronics)
|
From page 416... ...
Consequently, after a single exposure a person's blood lead level may begin to return to normal; the total body burden, however, may still be elevated. For lead poisoning to develop, major acute exposures to lead need not occur.
|
From page 417... ...
The lowest observable blood lead levels associated with specific health effects in chronically exposed children and adults are shown in Figure 1. Neurologic Effects The most sensitive target of lead poisoning is the nervous system.
|
From page 418... ...
lower IQ scores and cognitive deficits, at age 5. In another study that measured total body burden, primary school children with high tooth lead levels but with no known history of lead poisoning had larger deficits in psychometric intelligence scores, speech and language processing, attention, and classroom performance than children 8 ENVIRONMENTAL MEDICINE
|
From page 419... ...
Hearing loss may contribute to the apparent learning disabilities or poor classroom behavior exhibited by children with lead intoxication. Adults also experience CNS effects at relatively low blood lead levels, manifested by subtle behavioral changes, fatigue, and impaired concentration.
|
From page 420... ...
10 A strong inverse correlation exists between blood lead levels and levels of vitamin D Because the vitamin D-endocrine system is responsible in large part for the maintenance of extra- and intracellularcalcium homeostasis, it is likely that lead impairs cell growth and maturation and tooth and bone development.
|
From page 421... ...
home remodeling activities condition of household pets hobbies of all family members use of imported or glazed ceramics drinking water source and type of pipe nutritional status proximity to industrial facilities and hazardous waste sites 421 O The first signs of lead poisoning in children are often subtle neurobehavioral problems that adversely affect classroom behavior and social interaction. O Speech or hearing impairments, or both, are not uncommon In lead-exposed children.
|
From page 422... ...
Those symp toms most often associated with varying degrees of lead toxicity are listed below. In symptomatic lead intoxication, blood lead levels generally range from 35 to 50 ~dL in children and 40 to 60 ~dL in adults.
|
From page 423... ...
Patients exhibiting necrologic signs due to lead poisoning have been treated only for peripheral neuropathy or carpal tunnel syndrome, delaying treatment for lead intoxication. Failure to correctly diagnose leadinduced gastrointestinal distress has led to inappropriate abdominal surgery.
|
From page 424... ...
A blood lead level reflects lead's dynamic equilibrium between absorption, excretion, and deposition in soft- and hard-tissue compartments. Forchronic exposures, blood lead levels often underrepresent the total body burden; nevertheless, it is the most widely accepted and commonly used measure of lead exposure.
|
From page 425... ...
The presence of many children (or a large proportion of children) with blood lead levels in this range should trigger communitywide childhood lead poisoning Drevention activities.
|
From page 426... ...
recommends that children with blood lead levels of 45 pLg/dL or greater should be referred for appropriate chelation therapy immediately. Some practitioners routinely treat children with blood lead levels between 25 and 44 ~dL with chelation therapy and some do not use chelating agents for children with blood lead levels in this range.
|
From page 427... ...
Sorne practitioners use thle test when deciding whether to Institute chelation therapy for a patient with a blood lead level between 25 and 44 pg/dL Table 2. Chelating agents used In treating children who have lead poisoning Product Name Generic Name Chemical Name Abbreviation Calcium Disodium Edetatedisodium Calcium disodium CaNa2EDTA Versenate calcium ethylenediaminetetraacetate BALE in Oil Dimercaprol 2,3-dimercapto-1-propanol BALE Cuprimine D-penicillamine 3-mercapto-D-valine D-penicillamine Chemet Succimer Meso-2,-3-dimercaptosuccinic DMSA acid British anti-Lewisite Cha~n,0e_?
|
From page 428... ...
Regulation; by dry weight ACGIH = American Conference of Governmental Industnal Hygienists; CDC = Centers for Disease Control; CPSC = Consumer Product Safety Commission; EPA=Enviror~mental Protection Agency, FDA = Food and Drug Administration; NIOSH = National Institute for Occupational Safety and Health; 0SHA = Occupational Safety and Health Administration t If many children in the community have blood lead levels 2 10 1lg/dL, communitywide interventions (primary prevention activities) should be considered by appropriate agenc~es.
|
From page 429... ...
Between 1986 and 1988, several studies demonstrated neurobehavioral impairment in leadexposed children with blood lead levels as low as 10 to 14 ~g/dL. As more data become available, the definition of lead toxicity level will likely continue to be lowered (Figure 2)
|
From page 430... ...
consumesdrinkingwaterwith lead levels above 20 1lgidL. EPA is required to set drinking water standards with two levels of protection.
|
From page 431... ...
,, The company's test indicated thatherb/ood lead level was 62 pg/dL. What advice could you give the boy's mother regarding her former employment?
|
From page 432... ...
Deficits in psychologic and classroom performance of children with eJevated dentine lead levels.
|
From page 433... ...
Occupational and environmental lead poisoning associated with battery repair shops-Jamaica. Atlanta: US Department of Health and Human Services.
|
From page 434... ...
(9) Because of an incompletely developed blood-brain barrier, children under 36 months of age are particularly susceptible to necrologic damage at very low blood lead levels.
|
From page 435... ...
In lead-poisoned patients, anemia is usually evident only when the blood lead level is significantly elevated for prolonged periods. It manifests in only a relatively small number of children with chronic lead poisoning.
|
Key Terms
This material may be derived from roughly machine-read images, and so is provided only to facilitate research.
More
information on Chapter Skim is available.