Lead in Hair - Concern Over its Use as an Indicator of Non-Occupational Exposure

By Prof Brian Gulson
Graduate School of the Environment, Macquarie University, Sydney

With increasing public awareness of lead as a health issue, The LEAD group has received numerous calls regarding the availability and significance of lead measurements in hair and nails, but especially hair. Concern over the toxic effects of environmental factors such as heavy metals has also spawned an "Industry", promoting the use of trace metals in hair.

I was recently approached by a subject who had his hair analysed, informed that the lead was elevated and that he should undergo chelation therapy with EDTA. Brief details of this case are as follows.

Subject A is a 27 year old student who had experienced for at least the past three years symptoms which could be attributable to lead poisoning such as tiredness, sleep disruptions, disinterest in studies, indigestion and facial flushing. Discussions with the subject elicited no source 'of lead apart from the possibility of childhood exposure in Germany from petrol, because of the proximity of his residence to a busy thoroughfare.

A naturopath had suggested hair analysis, the results of which were 6.1 ppm Pb and 86 ppm Cu. The interpretation of the results was that both metal concentrations were high and it was recommended by a medical practitioner that the subject undergo chelation therapy with EDTA, with no follow-up or even a blood lead analysis!  Hair analyses are not considered reliable indicators of lead exposure, as discussed below.

He agreed to a blood lead analysis prior to chelation. Blood lead analyses - despite the drawbacks associated with a single analysis - are accepted internationally as the main indicator of lead exposure. Duplicate analyses of a blood sample using the stringent CSIRO protocol, showed it to contain 5.6 µg/dL, half the June 1993 NHMRC recommended goal for all Australians. Furthermore, the lead isotopic fingerprint indicated a source of Australian lead, not from Germany, although given that the subject has spent the past 22 years in Australia, it was highly unlikely that German lead would be detectable.

It is medically irresponsible for this subject to undergo chelation therapy with EDTA given:
(i) the internationally accepted indicator of lead exposure, blood lead, was not measured,
(ii) the potential side effects of EDTA chelation, including depletion of essential elements such as Zn, Fe and Cu, and even mobilisation of lead from skeletal sources (CDC 1991; Mann and Travers, 1991).

Status of Hair Analysis

Lead measurements in hair are not considered reliable indicators for exposure because of the difficulty to distinguish what is in the hair from what is on it. These problems arise form:
(i) the ease of external contamination (from air and dust, hair preparations (Fergusson, 1990; see table below)] because of the waxy nature of hair, and
(ii) the difficulty in decontaminating hair prior to analysis.

The CDC document (1991 page 55) states: "The following tests are NOT indicated for the diagnosis or clinical management of lead poisoning:

Tests of Hair and Fingernails for Lead Levels."

After a thorough study of the literature, Taylor (1986) came to the following conclusions, summarised by internationally regarded experts, Ewers and Brockhaus (1991):

1. Modern analytical procedures enable sensitive, accurate, and precise measurements of trace element concentrations in human hair. Since inter-laboratory comparisons indicate that the results are not always reliable, hair reference materials should be used throughout the analytical process to ensure accurate analytical data. As far as I know, no international reference materials are available.
2. The interpretation of the analytical data represents a complex problem since trace element concentrations of human hair are influenced by numerous factors including age and sex of the subject, colour and growth site. Therefore, it is vital that reference levels should be selected carefully so that these factors are taken into consideration. Unfortunately, much of the experimental and investigative work have failed to do so, and many studies are of doubtful validity. In addition, the contribution of external contamination of the trace element content of hair is very variable, and it is difficult or even impossible to control this factor.
3. Even where it has been possible to control for these influences the most reliable experimental data indicate that the trace element content of hair does not correlate with the trace element concentrations in metabolically important tissues. Such large and variable discrepancies were found that it is difficult to accept how the elemental concentrations in hair could reflect the trace element status of a subject. Those occasions in which the concentration of trace elements in hair can be shown to reflect either body status or exposure are essentially extreme situations, usually with significantly increased concentrations and evidence of toxicity. In these situations parameters other than hair concentrations are more informative.
4. With few exceptions mentioned above trace element analysis of hair is not a useful procedure, in many instances it provides data that may be misleading. The activities of laboratories which advertise and provide such analyses on a commercial basis can only be viewed with scepticism

The concerns expressed above for many trace elements is exacerbated in the case of lead because of its ubiquity.

A table of hair lead analyses from Fergusson (1990; Table 13.4, page 478; references included) also illustrates the variability in lead concentrations (in parts per million; ppm) and futility in the interpretation of data at low concentrations.

Conclusion

If the community wishes to avail itself of the "metals in hair" services, that is their prerogative. However, if as an outcome of these services, recommendations are proposed which could potentially impact negatively on a person's health with no amelioration of their problems, it is irresponsible for the service providers to make these recommendations.

References

CDC (1991). Preventing Lead Poisoning in Young Children. U.S. Department of Health and Human Services, Centers for Disease Control, Atlanta, Georgia.

Ewers U. and Brockhaus A. (1991). Metal concentrations in human body fluids and tissues. In: Metals and their compounds in the environment. Occurrence, analysis and biological relevance. Edited by E Merian. VCH Publishers Weinheim, Germany, 199 1, pages 207 - 220.

Fergusson JE (1990). The heavy elects: chemistry, environmental impact and health effects. Pergamon Press, Oxford.

Mann K.V. and Travers J.D. (1991). Succimer, and oral lead chelator. Clinical Pharmacy, 10, 914 -922.
Taylor A. (1986). Usefulness of measurements of trace elements in hair. Ann. Clin. Biochem. 23, 364-378

Contents   Previous Item   Next Item