An Acute Mercuric Mercury Poisoning: Chemical Speciation of Hair Mercury Shows a Peak of Inorganic Mercury Value T. Y.
1 H. Imai, 1 Suzuki, T. Hongo, , 1 1 N. Matsuo, 2 and H. Aoyama 2 M. Yoshida Yamamura, 2
M.
1 Nakazawa,
T.
1 Abe,
Department of Human Ecology, Faculty of Medicine, University of Tokyo, Hongo 7-3-1, Bunkyo1 of Public Health, St. Marianna University School of ku, Tokyo, 113 Japan, and Medicine, 2095, Sugao, Miyamae-ku, Kawasaki, 213 Japan
Department
A woman ingested a dose of sublimate (approximately 0.9 g) in an attempted suicide. She survived and recovered in response to a combination of therapies including chelate (BAL) therapy, plasma exchange, haemodialysis and peritoneal dialysis. Serum inorganic mercury concentration, urinary inorganic mercury excretion and hair inorganic and organic mercury and selenium concentrations, along the length from the scalp to the distal part, were measured. Longitudinal analysis of hair, revealed a peak in inorganic mercury corresponding to the time of mercury ingestion. Organic mercury and selenium in the hair had different patterns of longitudinal variation from that of inorganic mercury. The biological half-life (23.5 d) of serum inorganic mercury levels was in good agreement with values previously reported in the literature.
Introduction Some chemicals, those which enter the human and are incorporated into the hair, may leave a historical record of exposure or uptake.’1 This can be found by measuring the variation along a length of hair equivalent to the growth of several months or a few years, by cutting it into smaller segments and analysing each separately, or by analysing, longitudinally, a single strand with an appropriate technique such as X-ray fluorescence spectrometry.2 Several metals, including methylmercury, lead, and zinc, have been analysed in this manner. -1-6 Hair mercury values have been used to monitor the amount of methylmercury obtained from eating fish.~ However, the value of inorganic mercury in hair has been disregarded in the biological monitoring of mercury, for various reasons. The first reason is that the proportion of inorganic to total mercury in hair is usually less than 10% in fish-eating populations and the level of inorganic mercury very low, less than 1.0 pig g-l (5 nmol g ’).8 The second reason is that the sample might be contaminated with exogenous inorganic mercury, and the third is the lack of evidence that the hair inorganic mercury value reflects the mercury level in the kidneys. Our
body
Correspondence:
hair inorganic mercury is, thus, very limited; therefore, the longitudinal
knowledge regarding
variation of inorganic as well as organic mercury values was studied in the hair of a woman who had ingested a dose of mercuric chloride with suicidal intent. The longitudinal variation of selenium in the hair was also studied to test whether or not there was a synchronized fluctuation with changing mercury levels.
Case
history
On 31
March 1989, a 26-year-old woman attempted suicide by ingesting a dose (approximately 0.9 g) of powdered mercuric chloride. She visited a doctor 3 h after ingestion and instantly received gastric lavage. Then she was hospitalized and treated with chelation therapy
using dimercaprol (BAL), haemodialysis (HD) or continuous ambulatory peritoneal dialysis (CAPD) and plasma exchange. Anuria began on the following day (1 April) and continued until 14 April, after which urination resumed. After normalization of her serum urea nitrogen and creatinine levels on 21 April (21 d after mercury
T. Suzuki.
Downloaded from het.sagepub.com at The University of Iowa Libraries on June 27, 2015
.
.
54 1
ingestion), dialysis therapy was terminated. From day hospitalization until 10 May, intravenous hyperalimentation had supported her nutrition; though the infusion used contained glucose, an amino acid mixture, sodium, potassium, calcium and magnesium, but not trace elements (iron, copper, zinc, selenium and others). She recovered steadily and was discharged from the hospital on 3 August. To evaluate the effectiveness of the therapy and to monitor mercury metabolism, serum inorganic mercury and urinary inorganic mercury concentrations were measured in the laboratory of the Department of Public Health, St. Marianna University School of Medicine, with which the hospital is the
of
affiliated. ’
Methods
’
Statistical analysis To estimate the biological half-life (T1I2) of inorganic mercury and its confidence limits (TL and TU), the single compartment model was applied. TL and Tu were estimated from the confidence limits of the coefficient of the excretion rate, which were estimated with the method of Snedecor and Cochran.&dquo;
Results Serum inorganic mercury concentration Just after the hospitalization, the patient’s serum inorganic mercury concentration was extremely high, 116.5 nmol mi-1. However, with treatment, it was quickly suppressed to level below 10 nmol ml-’. Once treatment had ended it rebounded to a level slightly exceeding 10 nmol ml-’ and then decreased at an apparently constant rate
(Figure 1).
Blood and 24-h urine samples were collected on the ward. Hair was sampled three times (on 111 May, 4 July and 7 September) with the informed consent of the patient. Bundles of long hair, from several sites, were cut on the scalp surface. From the cut end to 12 cm length, hair samples were cut into 1 cm segments. Each segment was washed with 0.8% polyoxyethylene lauryl ether (Wako Pure Chemical, Tokyo) solution and then three times with distilled water in a supersonic cleaner (10 min for each washing). After being dried for 4 h at 80°C, the sample was stored to cool in a desiccator, and then cut into fine pieces with stainless scissors, weighed and subjected to mercury analysis. The mercury was analysed by Magos’ method.9 The original Magos’ method was used for selective inorganic mercury determination for serum and urine samples during hospitalization, and for inorganic and total mercury determination for plasma and erythrocytes, which were sampled twice around the time of the hair cutting. Organic mercury was extracted twice with a solution of 1 N HCI from the hair sample and the value of total mercury in the extract was presented as organic mercury; the residue being subjected to selective inorganic mercury determination and total mercury determination with Magos’ method. The difference between total and inorganic mercury values was added to the organic mercury value of the extract. Selenium was analysed by fluorometry’~’ after wet washing of the hair sample ’with HN03/HC104. To validate the accuracy of measurements, the reference hair material supplied from the National Institute for Environmental Studies of Japan (NIES No. 5 Human Hair) for mercury and NBS Bovine Liver (SRM 1577) for selenium were measured simultaneously.
..
--,-
Figure
1
_.--
oo.J-
Sequential change
of
..~_.~
serum
inorganic
mercury concentrations and daily urinary inorganic mercury excretion in a patient poisoned with sublimate. In the upper part of the figure, BAL indicates chelation therapy with dimercaprol and the arrows indicate the day of treatment with haemodialysis (HD), peritoneal dialysis (PD) and plasma exchange, respectively.
Downloaded from het.sagepub.com at The University of Iowa Libraries on June 27, 2015
55
Table 1
Inorganic
and total mercury concentrations in
erythrocytes
and
serum
102 and 159 d after mercury
ingestion
In the serum collected 102 and 159 d after mercury ingestion, the ratios of inorganic to total mercury were 98% and 91 % , respectively
(Table 1). Urinary inorganic mercury excretion The daily excretion of urinary inorganic mercury increased with time until day 30 when it began to decrease. With a fairly large day-to-day variation, it decreased gradually, but about 80 d after ingestion it began to increase again (Figure 1). Hair inorganic mercury concentration In the hair cut 41 d after mercury ingestion, a sharp peak (40 nmol g ’ , 8 Ilg g7 ) was found in the 1 cm segment closest to the scalp surface, while the levels were 5 nmol g-1 or less in all the other segments. The peak of inorganic mercury concentration shifted to the segment distant from the scalp, i.e. the 2-3 cm segment in the hair cut 95 d after ingestion and the 3-4 cm segment in the hair cut 160 d after ingestion, and the height of the peak decreased. In the hair cut 160 d after ingestion, the peak was not sharp, but had a wide base (Figure 2).
organic mercury concentration Organic mercury levels in the patient’s hair ranged from 30 to 65 nmol g-l, indicating that she often ate fish, and a peak concentration, which showed a temporary intake of a large amount of fish, or of fish containing a large amount of methylmercury, was present at different distances from the cut end according to the Hair
date
on
which the hair
was
cut, i.e. the 3-4
cm
segment in the hair cut 41 d after ingestion, the 5-6 cm segment in the hair cut 95 d after and the 6-7
cm
segment in the hair
cut
160 d after
(Figure 2). Hair selenium concentration Selenium was measured only in the hair sample cut 160 d after ingestion. It stayed at levels of 8-9 nmol g~l in the segments of distal part of the hair, but decreased to 6-7 nmol g-1 in those segments that were 1 to 5 cm from the cut end
(Figure 2).
2 Inorganic and organic mercury and selenium concentrations in the 1 cm length segments of hair sampled at different dates after the ingestion of sublimate. 0: cut 41 d after ingestion. 0: 95 d aftcr. 0: 160 d after.
Figure
Estimation of the biological half-lives of inorganic mercury in serum, urine and hair The estimated biological half-life of inorganic mercury in the patients serum was 23.5 d when the data after the termination of mercuryreducing therapies were used for estimation. In the decreasing phase of urinary mercury excretion
from day 25 to day 82 after mercury ingestion, T 1/2 of urinary inorganic mercury excretion was 25.9 d, a figure very close to the value for serum inorganic mercury. However, it was 57.8 d when estimated using the data obtained from the four segments of hair (Table 2).
Downloaded from het.sagepub.com at The University of Iowa Libraries on June 27, 2015
56
Table 2 Estimated biological half-life (T,/~) of inorganic mercury and its 95% confidence limits
and Tu: lower and upper estimations, respectively. * : daily urinary excretion. ** : data in the segments from cut end to 4 cm in a hair sample cut 160 d after ingestion; presumed to cover about 90 d the hair growth rate is considered to be about 1 cm month-’ .
T~
Discussion The ingested amount of mercuric chloride was estimated to be approximately 0.9 g (0.66 g as Hg) by the patient, who was a trained chemist working in a scientific institution. The lethal dose of mercuric chloride in adult humans has been estimated to be 1-4 g.~ Taking variation in body weight into account, 0.9 g of mercuric chloride should have been a lethal dose for a Japanese woman of 48 kg body weight (13.8 mg Hg kg~1). The treatments applied to this patient were successful in the sense that she survived despite the ingestion of a lethal dose. During the period of anuria, the serum inorganic mercury concentrations were suppressed at about 6-10 nmol ml-’, even though the initial serum value was an extremely high 116.5 nmol ml-1. After cessation of mercury-reducing treatments, the serum inorganic mercury decreased with a biological halflife of 23.5 d. This half-life value was in very good agreement with the value, 24 d, obtained from human volunteers who received a single oral tracer dose of mercuric chloride.~2 The fact that the daily urinary excretion of inorganic mercury happened to follow an identical pattern of reduction (TI/2: 25.9 d) to that of serum inorganic mercury may indicate the significance of the serum level in regulating urinary excretion for a certain period of time after mercury ingestion. However, the daily urinary inorganic mercury excretion returned to high levels 80 d after mercury ingestion in spite of the decreased serum inorganic mercury level (1 nmol mi-1 or less). This probably was the result of the release of accumulated inorganic mercury from the kidneys. In workers exposed to mercury vapour, the rate of urinary excretion of inorganic mercury was to the amount of suggested to be proportional 7 mercury in the kidneys.~ Inorganic mercury concentrations revealed a peak in the 1 cm segment nearest to the scalp in hair cut 41 d after mercury ingestion. Assuming
that the hair growth rate is 1 cm month-’ and that the time-lag between hair formation and its appearance above the scalp is about 10 d, this peak should reflect the average serum inorganic mercury concentrations during the 30 d after ingestion. Furthermore, if we consider that the hair was not cut precisely at the scalp surface, the time period the 0-1 cm segment covers is several days before and about 20 d after the mercury ingestion. The mechanism by which inorganic mercury enters the hair is unknown. In general, there are six sources of trace elements in the hair: incorporation via the matrix of the hair root and through the root sheath; sebum; eccrine sweat; apocrine sweat; desquamated epidermis; and exogenous contamination.’3 In the case of cxogenous contamination, the concentration becomes I higher in the distal part of the hair strand.’ Hence, incorporation via the hair root matrix and through the hair sheath is most likely, but the contribution of sebum, sweat and desquamated epidermis cannot be neglected. In the hair cut 95 d after mercury ingestion, a peak inorganic mercury concentration was observed in the 2-3 cm segment, although the concentration was lower than that in hair cut 41 d after. The timc difference between the 0-1 cm and the 2-3 cm segments may be about 60 d, which is roughly similar to the time elapsed between the dates of which the hair was cut, 54 d, but hair growth in the patient might have been slowed by the 40 days of artificial feeding. The inorganic mercury concentrations in the hair sample cut 160 d after ingestion reveal several problems: 1 The peak was in the 3-4 cm segment, which represents only 30 d in the hair sample cut 95 d
after ingestion. 2 The base of the peak was very broad, with an increase in inorganic mercury concentration in the 6-7 cm segment. 3 The estimated biological half-life (58 d) was markedly different from other estimations (24-28 d) based on the serum and urine data.
discrepancies can be explained by considering that there was a misalignment of hair strands in a bundle sample, a phenomenon that has already been discussed in detail by GiovanoliJakubczak and Berg. 14 Thus, the elongated halfThese
can be discarded. In the hair sampled from a population which consumed large amounts of fish contaminated with methylmercury, organic and inorganic mercury levels were linearly reflated, 15 but in this particular patient, the variation in organic mercury concentrations along the length of the hair was independent of the variation in inorganic mercury. In view of the evidence reviewed above, the chemical speciation of hair
life
Downloaded from het.sagepub.com at The University of Iowa Libraries on June 27, 2015
57
mercury may be useful in assessing the exposure or uptake of not only methylmercury but also mercuric mercury; at least in the case of a single massive exposure. Hair selenium concentrations did not correlate with either its organic or its inorganic mercury concentrations. Variation along the length of hairs rather indicates the effect of treatment during hospitalisation. The occurrence of low
selenium levels was reported in patients maintained by HD or CAPD. 16 The infusion used for intravenous hyperalimentation did not contain selenium or any other trace elements. Thus the lowered selenium levels in the segments 1-5 cm from the cut end of the sample obtained 160 d after ingestion may reflect selenium
plasma
deficiency.
References 1 Suzuki T. Hair and nails: advantages and pitfalls when used in biological monitoring. In: Biological Monitoring of Toxic Metals eds TW Clarkson, L Friberg, GF Nordberg & PR Sager, pp. 623-40. New York: Plenum Press, 1988. 2 Toribara TY & Muhs AG. Hair: a keeper of history. Arctic Anthropology 1984; 21: 99-108. 3 Al-Shahristani H & Shihab K. Variation of biological halflife of methylmercury in man. Archives of Environmental Health 1974; 28: 342-4. 4 Suzuki T, Shishido-Kashiwazaki S, Igata A & Niina K. Hair mercury value and fish-eating habit. Ecology of Food and Nutrition 1979; 8: 117-22. 5 Grandjean P. Lead poisoning: Hair analysis shows the calendar of events. Human Toxicology 1984; 3: 223-8. 6 Toribara TY & Jackson DA. X-ray fluorescence measurement of the zinc profile of a single hair. Clinical Chemistry 1982; 28: 650-4. 7 Clarkson TW, Hursh JB, Sager PR & Syversen TLM. Mercury. In: Biological Monitoring of Toxic Metals, eds TW Clarkson, L Friberg, GF Nordberg & PR Sager, pp. 199246. New York: Plenum Press, 1988. 8 Suzuki T, Shishido S & Ishihara N. Interaction of inorganic to organic mercury in their metabolism in human body. International Archives of Occupational and Environmental Health 1976; : 103-13. 38 9 Magos L. Selective atomic absorption determination of inorganic mercury and methylmercury in undigested biological samples. Analyst 1971; 96: 847-53.
10
Watkinson JH. Fluorometric determination of selenium in biological material with 2,3-diaminonaphthalene. Analytical Chemistry 1966; 38; 92-7. 11 Snedecor GW & Cochran WG. Statistical Methods. Ames: Iowa State University Press, 1980. 12 Rahola T, Hattula T, Korolainen A & Miettinen JK. Elimination of free and protein-bound ionic mercury ) 2 ( Hg 2+ 03
Annals of Clinical Research 1973; 5: 214-19. in 13 Bos AJJ, der Stap CCAH, Valkovic V, Vis RD man.
van
& Verheul H. Incorporation routes of elements into human hair; implications for hair analysis used for monitoring. Science of the Total Environment 1985; 42: 157-69. 14 Giovanoli-Jakubczak T & Berg GG. Measurement of mercury in human hair. Archives of Environmental Health 1974; 28: 139-44. 15 Phelps RW, Clarkson TW, Kershaw TG & Wheatley B. Interrelationships of blood and hair mercury concentrations in a North American population exposed to methylmercury. Archives of Health 1980; 35: 161-8. 16 Dworkin B, Weseley S, Rosenthal WS, Schwartz EM & Weiss L. Diminished blood selenium levels in renal failure patients on dialysis: Correlations with nutritional status. American Journal of the Medical Sciences 1987; 293: 6-12.
Environmental
(Received 24 May 1991; accepted 4 June 1991)
Downloaded from het.sagepub.com at The University of Iowa Libraries on June 27, 2015
1 H. Imai, 1 Suzuki, T. Hongo, , 1 1 N. Matsuo, 2 and H. Aoyama 2 M. Yoshida Yamamura, 2
M.
1 Nakazawa,
T.
1 Abe,
Department of Human Ecology, Faculty of Medicine, University of Tokyo, Hongo 7-3-1, Bunkyo1 of Public Health, St. Marianna University School of ku, Tokyo, 113 Japan, and Medicine, 2095, Sugao, Miyamae-ku, Kawasaki, 213 Japan
Department
A woman ingested a dose of sublimate (approximately 0.9 g) in an attempted suicide. She survived and recovered in response to a combination of therapies including chelate (BAL) therapy, plasma exchange, haemodialysis and peritoneal dialysis. Serum inorganic mercury concentration, urinary inorganic mercury excretion and hair inorganic and organic mercury and selenium concentrations, along the length from the scalp to the distal part, were measured. Longitudinal analysis of hair, revealed a peak in inorganic mercury corresponding to the time of mercury ingestion. Organic mercury and selenium in the hair had different patterns of longitudinal variation from that of inorganic mercury. The biological half-life (23.5 d) of serum inorganic mercury levels was in good agreement with values previously reported in the literature.
Introduction Some chemicals, those which enter the human and are incorporated into the hair, may leave a historical record of exposure or uptake.’1 This can be found by measuring the variation along a length of hair equivalent to the growth of several months or a few years, by cutting it into smaller segments and analysing each separately, or by analysing, longitudinally, a single strand with an appropriate technique such as X-ray fluorescence spectrometry.2 Several metals, including methylmercury, lead, and zinc, have been analysed in this manner. -1-6 Hair mercury values have been used to monitor the amount of methylmercury obtained from eating fish.~ However, the value of inorganic mercury in hair has been disregarded in the biological monitoring of mercury, for various reasons. The first reason is that the proportion of inorganic to total mercury in hair is usually less than 10% in fish-eating populations and the level of inorganic mercury very low, less than 1.0 pig g-l (5 nmol g ’).8 The second reason is that the sample might be contaminated with exogenous inorganic mercury, and the third is the lack of evidence that the hair inorganic mercury value reflects the mercury level in the kidneys. Our
body
Correspondence:
hair inorganic mercury is, thus, very limited; therefore, the longitudinal
knowledge regarding
variation of inorganic as well as organic mercury values was studied in the hair of a woman who had ingested a dose of mercuric chloride with suicidal intent. The longitudinal variation of selenium in the hair was also studied to test whether or not there was a synchronized fluctuation with changing mercury levels.
Case
history
On 31
March 1989, a 26-year-old woman attempted suicide by ingesting a dose (approximately 0.9 g) of powdered mercuric chloride. She visited a doctor 3 h after ingestion and instantly received gastric lavage. Then she was hospitalized and treated with chelation therapy
using dimercaprol (BAL), haemodialysis (HD) or continuous ambulatory peritoneal dialysis (CAPD) and plasma exchange. Anuria began on the following day (1 April) and continued until 14 April, after which urination resumed. After normalization of her serum urea nitrogen and creatinine levels on 21 April (21 d after mercury
T. Suzuki.
Downloaded from het.sagepub.com at The University of Iowa Libraries on June 27, 2015
.
.
54 1
ingestion), dialysis therapy was terminated. From day hospitalization until 10 May, intravenous hyperalimentation had supported her nutrition; though the infusion used contained glucose, an amino acid mixture, sodium, potassium, calcium and magnesium, but not trace elements (iron, copper, zinc, selenium and others). She recovered steadily and was discharged from the hospital on 3 August. To evaluate the effectiveness of the therapy and to monitor mercury metabolism, serum inorganic mercury and urinary inorganic mercury concentrations were measured in the laboratory of the Department of Public Health, St. Marianna University School of Medicine, with which the hospital is the
of
affiliated. ’
Methods
’
Statistical analysis To estimate the biological half-life (T1I2) of inorganic mercury and its confidence limits (TL and TU), the single compartment model was applied. TL and Tu were estimated from the confidence limits of the coefficient of the excretion rate, which were estimated with the method of Snedecor and Cochran.&dquo;
Results Serum inorganic mercury concentration Just after the hospitalization, the patient’s serum inorganic mercury concentration was extremely high, 116.5 nmol mi-1. However, with treatment, it was quickly suppressed to level below 10 nmol ml-’. Once treatment had ended it rebounded to a level slightly exceeding 10 nmol ml-’ and then decreased at an apparently constant rate
(Figure 1).
Blood and 24-h urine samples were collected on the ward. Hair was sampled three times (on 111 May, 4 July and 7 September) with the informed consent of the patient. Bundles of long hair, from several sites, were cut on the scalp surface. From the cut end to 12 cm length, hair samples were cut into 1 cm segments. Each segment was washed with 0.8% polyoxyethylene lauryl ether (Wako Pure Chemical, Tokyo) solution and then three times with distilled water in a supersonic cleaner (10 min for each washing). After being dried for 4 h at 80°C, the sample was stored to cool in a desiccator, and then cut into fine pieces with stainless scissors, weighed and subjected to mercury analysis. The mercury was analysed by Magos’ method.9 The original Magos’ method was used for selective inorganic mercury determination for serum and urine samples during hospitalization, and for inorganic and total mercury determination for plasma and erythrocytes, which were sampled twice around the time of the hair cutting. Organic mercury was extracted twice with a solution of 1 N HCI from the hair sample and the value of total mercury in the extract was presented as organic mercury; the residue being subjected to selective inorganic mercury determination and total mercury determination with Magos’ method. The difference between total and inorganic mercury values was added to the organic mercury value of the extract. Selenium was analysed by fluorometry’~’ after wet washing of the hair sample ’with HN03/HC104. To validate the accuracy of measurements, the reference hair material supplied from the National Institute for Environmental Studies of Japan (NIES No. 5 Human Hair) for mercury and NBS Bovine Liver (SRM 1577) for selenium were measured simultaneously.
..
--,-
Figure
1
_.--
oo.J-
Sequential change
of
..~_.~
serum
inorganic
mercury concentrations and daily urinary inorganic mercury excretion in a patient poisoned with sublimate. In the upper part of the figure, BAL indicates chelation therapy with dimercaprol and the arrows indicate the day of treatment with haemodialysis (HD), peritoneal dialysis (PD) and plasma exchange, respectively.
Downloaded from het.sagepub.com at The University of Iowa Libraries on June 27, 2015
55
Table 1
Inorganic
and total mercury concentrations in
erythrocytes
and
serum
102 and 159 d after mercury
ingestion
In the serum collected 102 and 159 d after mercury ingestion, the ratios of inorganic to total mercury were 98% and 91 % , respectively
(Table 1). Urinary inorganic mercury excretion The daily excretion of urinary inorganic mercury increased with time until day 30 when it began to decrease. With a fairly large day-to-day variation, it decreased gradually, but about 80 d after ingestion it began to increase again (Figure 1). Hair inorganic mercury concentration In the hair cut 41 d after mercury ingestion, a sharp peak (40 nmol g ’ , 8 Ilg g7 ) was found in the 1 cm segment closest to the scalp surface, while the levels were 5 nmol g-1 or less in all the other segments. The peak of inorganic mercury concentration shifted to the segment distant from the scalp, i.e. the 2-3 cm segment in the hair cut 95 d after ingestion and the 3-4 cm segment in the hair cut 160 d after ingestion, and the height of the peak decreased. In the hair cut 160 d after ingestion, the peak was not sharp, but had a wide base (Figure 2).
organic mercury concentration Organic mercury levels in the patient’s hair ranged from 30 to 65 nmol g-l, indicating that she often ate fish, and a peak concentration, which showed a temporary intake of a large amount of fish, or of fish containing a large amount of methylmercury, was present at different distances from the cut end according to the Hair
date
on
which the hair
was
cut, i.e. the 3-4
cm
segment in the hair cut 41 d after ingestion, the 5-6 cm segment in the hair cut 95 d after and the 6-7
cm
segment in the hair
cut
160 d after
(Figure 2). Hair selenium concentration Selenium was measured only in the hair sample cut 160 d after ingestion. It stayed at levels of 8-9 nmol g~l in the segments of distal part of the hair, but decreased to 6-7 nmol g-1 in those segments that were 1 to 5 cm from the cut end
(Figure 2).
2 Inorganic and organic mercury and selenium concentrations in the 1 cm length segments of hair sampled at different dates after the ingestion of sublimate. 0: cut 41 d after ingestion. 0: 95 d aftcr. 0: 160 d after.
Figure
Estimation of the biological half-lives of inorganic mercury in serum, urine and hair The estimated biological half-life of inorganic mercury in the patients serum was 23.5 d when the data after the termination of mercuryreducing therapies were used for estimation. In the decreasing phase of urinary mercury excretion
from day 25 to day 82 after mercury ingestion, T 1/2 of urinary inorganic mercury excretion was 25.9 d, a figure very close to the value for serum inorganic mercury. However, it was 57.8 d when estimated using the data obtained from the four segments of hair (Table 2).
Downloaded from het.sagepub.com at The University of Iowa Libraries on June 27, 2015
56
Table 2 Estimated biological half-life (T,/~) of inorganic mercury and its 95% confidence limits
and Tu: lower and upper estimations, respectively. * : daily urinary excretion. ** : data in the segments from cut end to 4 cm in a hair sample cut 160 d after ingestion; presumed to cover about 90 d the hair growth rate is considered to be about 1 cm month-’ .
T~
Discussion The ingested amount of mercuric chloride was estimated to be approximately 0.9 g (0.66 g as Hg) by the patient, who was a trained chemist working in a scientific institution. The lethal dose of mercuric chloride in adult humans has been estimated to be 1-4 g.~ Taking variation in body weight into account, 0.9 g of mercuric chloride should have been a lethal dose for a Japanese woman of 48 kg body weight (13.8 mg Hg kg~1). The treatments applied to this patient were successful in the sense that she survived despite the ingestion of a lethal dose. During the period of anuria, the serum inorganic mercury concentrations were suppressed at about 6-10 nmol ml-’, even though the initial serum value was an extremely high 116.5 nmol ml-1. After cessation of mercury-reducing treatments, the serum inorganic mercury decreased with a biological halflife of 23.5 d. This half-life value was in very good agreement with the value, 24 d, obtained from human volunteers who received a single oral tracer dose of mercuric chloride.~2 The fact that the daily urinary excretion of inorganic mercury happened to follow an identical pattern of reduction (TI/2: 25.9 d) to that of serum inorganic mercury may indicate the significance of the serum level in regulating urinary excretion for a certain period of time after mercury ingestion. However, the daily urinary inorganic mercury excretion returned to high levels 80 d after mercury ingestion in spite of the decreased serum inorganic mercury level (1 nmol mi-1 or less). This probably was the result of the release of accumulated inorganic mercury from the kidneys. In workers exposed to mercury vapour, the rate of urinary excretion of inorganic mercury was to the amount of suggested to be proportional 7 mercury in the kidneys.~ Inorganic mercury concentrations revealed a peak in the 1 cm segment nearest to the scalp in hair cut 41 d after mercury ingestion. Assuming
that the hair growth rate is 1 cm month-’ and that the time-lag between hair formation and its appearance above the scalp is about 10 d, this peak should reflect the average serum inorganic mercury concentrations during the 30 d after ingestion. Furthermore, if we consider that the hair was not cut precisely at the scalp surface, the time period the 0-1 cm segment covers is several days before and about 20 d after the mercury ingestion. The mechanism by which inorganic mercury enters the hair is unknown. In general, there are six sources of trace elements in the hair: incorporation via the matrix of the hair root and through the root sheath; sebum; eccrine sweat; apocrine sweat; desquamated epidermis; and exogenous contamination.’3 In the case of cxogenous contamination, the concentration becomes I higher in the distal part of the hair strand.’ Hence, incorporation via the hair root matrix and through the hair sheath is most likely, but the contribution of sebum, sweat and desquamated epidermis cannot be neglected. In the hair cut 95 d after mercury ingestion, a peak inorganic mercury concentration was observed in the 2-3 cm segment, although the concentration was lower than that in hair cut 41 d after. The timc difference between the 0-1 cm and the 2-3 cm segments may be about 60 d, which is roughly similar to the time elapsed between the dates of which the hair was cut, 54 d, but hair growth in the patient might have been slowed by the 40 days of artificial feeding. The inorganic mercury concentrations in the hair sample cut 160 d after ingestion reveal several problems: 1 The peak was in the 3-4 cm segment, which represents only 30 d in the hair sample cut 95 d
after ingestion. 2 The base of the peak was very broad, with an increase in inorganic mercury concentration in the 6-7 cm segment. 3 The estimated biological half-life (58 d) was markedly different from other estimations (24-28 d) based on the serum and urine data.
discrepancies can be explained by considering that there was a misalignment of hair strands in a bundle sample, a phenomenon that has already been discussed in detail by GiovanoliJakubczak and Berg. 14 Thus, the elongated halfThese
can be discarded. In the hair sampled from a population which consumed large amounts of fish contaminated with methylmercury, organic and inorganic mercury levels were linearly reflated, 15 but in this particular patient, the variation in organic mercury concentrations along the length of the hair was independent of the variation in inorganic mercury. In view of the evidence reviewed above, the chemical speciation of hair
life
Downloaded from het.sagepub.com at The University of Iowa Libraries on June 27, 2015
57
mercury may be useful in assessing the exposure or uptake of not only methylmercury but also mercuric mercury; at least in the case of a single massive exposure. Hair selenium concentrations did not correlate with either its organic or its inorganic mercury concentrations. Variation along the length of hairs rather indicates the effect of treatment during hospitalisation. The occurrence of low
selenium levels was reported in patients maintained by HD or CAPD. 16 The infusion used for intravenous hyperalimentation did not contain selenium or any other trace elements. Thus the lowered selenium levels in the segments 1-5 cm from the cut end of the sample obtained 160 d after ingestion may reflect selenium
plasma
deficiency.
References 1 Suzuki T. Hair and nails: advantages and pitfalls when used in biological monitoring. In: Biological Monitoring of Toxic Metals eds TW Clarkson, L Friberg, GF Nordberg & PR Sager, pp. 623-40. New York: Plenum Press, 1988. 2 Toribara TY & Muhs AG. Hair: a keeper of history. Arctic Anthropology 1984; 21: 99-108. 3 Al-Shahristani H & Shihab K. Variation of biological halflife of methylmercury in man. Archives of Environmental Health 1974; 28: 342-4. 4 Suzuki T, Shishido-Kashiwazaki S, Igata A & Niina K. Hair mercury value and fish-eating habit. Ecology of Food and Nutrition 1979; 8: 117-22. 5 Grandjean P. Lead poisoning: Hair analysis shows the calendar of events. Human Toxicology 1984; 3: 223-8. 6 Toribara TY & Jackson DA. X-ray fluorescence measurement of the zinc profile of a single hair. Clinical Chemistry 1982; 28: 650-4. 7 Clarkson TW, Hursh JB, Sager PR & Syversen TLM. Mercury. In: Biological Monitoring of Toxic Metals, eds TW Clarkson, L Friberg, GF Nordberg & PR Sager, pp. 199246. New York: Plenum Press, 1988. 8 Suzuki T, Shishido S & Ishihara N. Interaction of inorganic to organic mercury in their metabolism in human body. International Archives of Occupational and Environmental Health 1976; : 103-13. 38 9 Magos L. Selective atomic absorption determination of inorganic mercury and methylmercury in undigested biological samples. Analyst 1971; 96: 847-53.
10
Watkinson JH. Fluorometric determination of selenium in biological material with 2,3-diaminonaphthalene. Analytical Chemistry 1966; 38; 92-7. 11 Snedecor GW & Cochran WG. Statistical Methods. Ames: Iowa State University Press, 1980. 12 Rahola T, Hattula T, Korolainen A & Miettinen JK. Elimination of free and protein-bound ionic mercury ) 2 ( Hg 2+ 03
Annals of Clinical Research 1973; 5: 214-19. in 13 Bos AJJ, der Stap CCAH, Valkovic V, Vis RD man.
van
& Verheul H. Incorporation routes of elements into human hair; implications for hair analysis used for monitoring. Science of the Total Environment 1985; 42: 157-69. 14 Giovanoli-Jakubczak T & Berg GG. Measurement of mercury in human hair. Archives of Environmental Health 1974; 28: 139-44. 15 Phelps RW, Clarkson TW, Kershaw TG & Wheatley B. Interrelationships of blood and hair mercury concentrations in a North American population exposed to methylmercury. Archives of Health 1980; 35: 161-8. 16 Dworkin B, Weseley S, Rosenthal WS, Schwartz EM & Weiss L. Diminished blood selenium levels in renal failure patients on dialysis: Correlations with nutritional status. American Journal of the Medical Sciences 1987; 293: 6-12.
Environmental
(Received 24 May 1991; accepted 4 June 1991)
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