|
Indoor
& Outdoor Dust & Soil Lead Levels
By: Thomas D. Matte,
MD, MPH - Division of Environmental Hazards and Health Effects, National Center for
Environmental Health, Centers for Disease Control and Prevention, Atlanta, Georgia, USA.
The
following is an extract of the June 23/30 Journal of the American Medical Association.
Editorial - Reducing Blood Lead Levels Benefits and Strategies [June 23/30 JAMA.
1999;281:2340-2342] (c) AMA 1999© All rights reserved.
The
study by Simon and Hudes [11] concerns …potential interventions to reduce the risk of
lead toxic effects… An …unfortunate limitation of this study is the lack of data
on the group of greatest interest—children younger than 6 years. Even though a
beneficial effect of ascorbic acid supplements on lead levels is supported by a recent
report from a small randomized trial in adult smokers, [15] more evidence from controlled
intervention trials is needed to demonstrate the real value, if any, of increased ascorbic
acid intake, especially in young children. Even if a nutritional manipulation is proven
effective in reducing blood lead levels, reliance on such an intervention places most of
the burden for prevention on those most affected and least responsible for the underlying
environmental causes of lead toxicity. [16] Nutritional interventions, therefore, must
never substitute for efforts to reduce lead exposure to safe levels. On the other hand,
when used as an adjunct to environmental measures, some nutritional changes may prove to
have benefits beyond any impact on lead toxicity. For example, studies have suggested
benefits of higher ascorbic acid intake on blood pressure, [17] blood lipid profiles, [18]
and respiratory symptoms. [19] What needs to be done to hasten the reduction of lead
exposure, especially for the populations most affected? While existing efforts, such as
screening and responding to lead-poisoned children, need to continue, it would seem
reasonable to propose expanded activity on 2 fronts in particular. First, public and
private efforts should be made to increase the testing and remediation of residential lead
hazards from deteriorated paint and contaminated dust before children develop lead toxic
effects. Interior dust lead measurements, available at relatively low cost, can now be
used to help identify the most immediately hazardous dwellings, [20] and interventions are
available to substantially reduce residential lead exposure. [21] The use of this
relatively inexpensive test should be expanded, thus decreasing the reliance on elevated
blood lead levels in children to identify hazardous home environments. Second, additional
research is needed regarding the sources, fate, and remediation of contaminated exterior
dust and soil, which can have major effects on blood lead levels. [20,22] Approximately
11% of pre-1980 homes are estimated to have soil lead concentrations exceeding 1000 ppm,
[23] and lead levels in some urban communities may be comparable to those found in
communities contaminated by smelting and mining operations. [20] Practical interventions
and the resources to implement them in large urban areas are currently lacking.
Editorials
represent the opinions of the authors and THE JOURNAL and not those of the American
Medical Association. Reprints are not available from the author.
[Selected]
References
- 11.
Simon JA, Hudes ES. Relationship of ascorbic acid to blood lead levels. JAMA.
1999;281:2289-2293.
- 15.
Dawson EB, Evans DR, Harris WA, Teter MC, McGanity WJ. The effect of ascorbic acid
supplementation on the blood lead levels of smokers. J Am Coll Nutr. 1999;18:166-170.
- 16.
Hu H, Kotha S, Brennan T. The role of nutrition in mitigating environmental insults:
policy and ethical issues. Environ Health Perspect. 1995;103(suppl 6): 185-190.
- 17.
Ness AR, Chee D, Elliott P. Vitamin C and blood pressure—an overview. J Hum
Hypertens. 1997;11:343-350.
- 18.
Simon JA, Hudes ES. Relation of serum ascorbic acid to serum lipids and lipoproteins in US
adults. J Am Coll Nutr. 1998;17:250-255.
- 19.
Schwartz J, Weiss ST. Dietary factors and their relation to respiratory symptoms: the
Second National Health and Nutrition Examination Survey. Am J Epidemiol. 1990;132:67-76.
- 20.
Lanphear BP, Matte TD, Rogers J, et al. The contribution of lead-contaminated house dust
and residential soil to children's blood lead levels. Environ Res. 1998;79:51-68.
- 21.
Farfel MR, Chisolm JJ Jr, Rohde CA. The longer-term effectiveness of residential lead
paint abatement. Environ Res. 1994;66:217-221.
- 22.
Bornschein RL, Succop P, Kraft KM, Clark CS, Peace B, Hammond PB. Exterior surface dust
lead, interior house dust lead and childhood lead exposure in an urban environment. In:
Hemphill DD, ed. Trace Substances in Environmental Health, XX: Proceedings of University
of Missouri's 20th Annual Conference, June 1986. Columbia: University of Missouri;
1987:322-332.
- 23.
Environmental Protection Agency. Distribution of Soil Lead in the Nation's Housing Stock.
Washington, DC: Office of Pollution Prevention and Toxics. Environmental Protection
Agency; 1996. Report No. EPA 747-R-96-003.
|
