Tissue
Mercury
induced
Levels
Nephrotic
in the
Mercury-
Syndrome
R. D. BARR, M.R.C.P., H. SMITH, B . S C , P H . D . , AND
H. M. CAMERON, M.D.,
F.R.C.PATH.
Departments of Medicine and Pathology, University of Nairobi, Nairobi, Kenya, and
Department of Forensic Medicine, University of Glasgow, Glasgow, Scotland
ABSTRACT
Barr, R. D., Smith, H., and Cameron, H. M.: Tissue mercury levels in the
mercury-induced nephrotic syndrome. Am. J. Clin. Pathol. 59: 515-517, 1973.
Levels of mercury in scalp hair, pubic hair, and fingernails were found to
reflect the use of mercury-containing skin-lightening creams, the causal agents
of many cases of the adult nephrotic syndrome seen in Africans in Kenya.
STRONG EVIDENCE supporting an eiiologic
relationship between the self-administration of skin-lightening creams containing
ammoniated mercury and the development
of a nephrotic syndrome has been presented by Barr and associates.1 Barr and colleagues 1 ' 2 have demonstrated good correlation between exposure to mercury in this
form and levels of mercury in the urine of
patients with nephrotic syndrome and normal individuals. However, since it has been
shown that when the use of these preparations is discontinued, levels of mercury in
urine fall to within normal limits in a period of a few weeks,2 it was decided to use
a method of detecting previous exposure
to mercury for a longer time interval following its use. Although the kidney retains
more mercury than any other organ, 8 renal
biopsy could not be justified simply to determine the presence or absence of mercury
in the body. T h e metal is, however, readily
detectable in other biologic materials; 10
therefore, hair and nails were chosen for
analysis in the present study. Levels of
mercury in hair and nails of subjects not
known to have been exposed to the metal
have been determined. 6
Patients and Methods
Thirty-five patients, 27 women and 8
men, from the ages of 15 to 56 years, were
included in the study. All were diagnosed as
having nephrotic syndrome by standard criteria. Clippings of approximately the terminal half inch of scalp hair and pubic
hair and clippings of fingernails were collected into plastic bags, and these specimens subsequently subjected to neutron activation analysis for the presence and quantity of mercury.10 There were fewer samples
of pubic hair and nails than of scalp hair
because of the common habits of shaving
the pubic area and nail biting among the
young women in this area. Analysis of the
results was performed by the distribution
free test of Kruskal and Wallis. 3
Results
Received April 17, 1072; acceplcd for publication
June IS, 11)72.
Patients included in the study were sepaOr. Han's present address is: Department of rated into three groups based on their use
Medicine, University of Aberdeen, Foresterhill, Abof skin-lightening creams containing mererdeen AB9 2ZD, Scotland, U.K.
515
516
A.J.C.P.—Vol. 59
BARR ET AL.
Table 1. Analvsis of Results*
Tissue
Index
Group A
Group B
2341
12
28.4
189
13
14.5
Total of ranks
Number of samples
Mean rank
Scalp hair
Total of ranks
Number of samples
Mean
156
11
14.2
191
10
19.1
Total of ranks
Number of samples
Mean
Chi-squared
Chi-squared
Chi-squared
Chi-squared
59
7
8.4
6.95; p <0.05
4.86; p <0.05
2.09; 0.20 > p> 0.10
Chi-squared (A-B-C)
Chi-squared (A—B+C)
Chi-squared (B-C+A)
Fingernails
100
10
10
19.98 p < 0.001
17.42 p < 0.001
2.56 p < 0.10
Chi-squared (A-B-C)
Chi-squared (A-B+C)
Chi-squared (B-C+A)
Pubic hair
Group C
140
9
15.6
207
11
18.8
88
9
9.8
5.63 0.10 > p> 0.05
3.56 0.10 > p> 0.05
2.07 0.20 > p> 0.10
4.90
p < 0.05
(A—B —C)
(A-B+C)
(C-B+A)
(C—B+A)
* Group A used skin-lightening creams containing mercury within 6 months of specimen sampling; group B discontinued use
of skin-lightening creams more than 6 months before sampling; group C had not used skin-lightening creams at any time.
Table 2. Tissue Mercury Levels (parts per million)*
Tissue
Scalp hair
Group B
Group A
20.5, 104,
898,
902,
2090, 3420,
252,
1280,
4800,
Pubic hair
5.2,
31.9,
542,
22.7,
26,
50,
352,
824, 1470,
Fingernails
5,
20.3,
156,
6.7,
78.8,
498,
9.4,
78.8,
840,
685,
1620,
9220
2.7,
11.2,
45.8,
768
27.3,
4.2,
11.4,
55.4,
17.7,
107,
1.1,
23.1,
274
Group C
5.4,
8.8, 10.5,
11.3, 11.3, 15,
57, 344, 490,
6.7,
8.5,
14.8, 27.1,
88.5, 1490
2.4,
40.5,
10.9,
29.1,
8.1, 10.9,
42, 152,
0.5, 0.6, 1.6,
10.8, 14.6, 14.9,
16.7, 20.1, 23.4
7.2,
1.8, 5.3,
0,
9.2, 19.7, 85
7.7,
0.4, 1.4, 2.6, 7.8,
8.9, 10, 13.2, 21.3,
22
* Group A used skin-lightening creams containing mercury within 6 months of specimen sampling; group B discontinued use
of skin-lightening creams more than 6 months before sampling; group C had not used skin-lightening creams at any time.
cury, as follows: group A had used these
preparations within 6 months of specimen
sampling; group B had discontinued the
use of these creams more than 6 months
before sampling; group C had not used
skin-lightening creams containing mercury
at any time. The numbers of samples from
each group is noted in Table 1.
Levels of mercury in hair and nails are
expressed in Table 2. With regard to scalp
and pubic hair, patients in group A had
significantly higher mercury levels than
did patients in the other two groups. There
was no statistically significant difference
among the levels of mercury in nails from
patients in the three groups (Table 1).
April 1973
MERCURY LEVELS AND NEPHROTIC SYNDROME
Discussion
The decision to separate patients in
group A from those in group B on the basis
of a time interval of 6 months prior to
sampling was taken on the assumption that
the mean hair length in our patients was
approximately 3 in. and the average growth
rate of hair was y2 in. per month. 5 Although
levels of mercury in urine generally reflect
current exposure to mercury, these levels
may fluctuate widely in any individual. 2 ' 7
The usefulness of this estimation is restricted considerably when exposure to the
metal has been discontinued. 2 Less direct
evidence of exposure to mercury may be
obtained from the demonstration of mercurialentis, 9 a fairly constant finding in
situations of chronic exposure, often occurring in the absence of clinical evidence of
systemic mercurialism.4 The results of the
present study indicate that estimation of
mercury in hair and nails, in addition to
being reliable and completely safe, offers a
useful direct means of detecting previous
exposure to the metal. Scalp hair appears
to be the most useful tissue in this respect.
However, when the period between sampling and exposure to mercury is greater
than 6 months, the mercury levels in scalp
and pubic hair are not significantly different from those in individuals not exposed
to mercury in the form of skin-lightening
creams. This suggests that patients in
group B have "excreted" their mercury
load, probably in large part by cutting and
washing the hair. Although no statistically
significant difference among levels of mercury in nails in the three groups could be
517
demonstrated, inspection of the mean rank
number for each group revealed the same
trend as with scalp and pubic hair, i.e.,
A > B > C. Furthermore, statistical comparison of C to B + A gave a chi-square
result suggesting a difference. These observations indicate that mercury may be excreted in nails at lower levels over longer
periods of time. It is of considerable interest in this respect that the growth rate
of nails is known to be much slower than
that of hair. 5 The wide ranges of levels of
mercury in groups A and B, for all three
tissues, are believed to reflect great variability in rates of excretion of the metal.
Acknowledgments. Mr. W. Gemert gave advice on
the statistical analysis, Professor W. F. M. Fulton
gave advice and encouragement, and Dr. P. J.
Munano, Chief Administrator, Kenyatta National
Hospital, Nairobi, gave permission to publish this
report.
References
1. Barr RD, Rees PH, Cordy PE, et al: The nephrotic syndrome in adult Africans in Nairobi. Br Med J 2:131-134, 1972
2. Barr RD, Woodger BA, Rees PH: Urine mercury levels and the use of skin-lightening
creams. Am J Clin Pathol 59:35-40, 1973
3. Bradley JV: Distribution Free Statistical Tests.
New York, Prentice-Hall, 1968, p 129
4. Burn RA: Mercurialentis. Proc Roy Soc Med
55:322-326, 1962
5. Glaister J: Medical Jurisprudence and Toxicology. Eleventh edition. Edinburgh, Livingstone, 1962, p 507
6. Howie RA, Smith H: Mercury in human tissue.
J Forensic Sci Soc 7:90-96, 1967
7. Jacobs MB, Ladd AC, Goldwalter LJ: Absorption and excretion of mercury in man. Arch
Environ Health 9:454-463, 1964
8. Kazantsis G: Mercury and the kidney. Trans Soc
Occup Med 20:54-59, 1970
9. Locket S, Nazroo IA: Eye changes following exposure to metallic mercury. Lancet 1:528-530,
1952
10. Smith H: Estimation of mercury in biological
material by neutron activation analysis. Anal
Chem 35:635-636, 1963