278
A. Kobal et al.
correlated to plasma mercury, have a greater potential also for the estimation of
current group level exposure. Our results suggested that the average mercury
concentrations in the morning urine samples of the observed miners can replace
the 18-h (or 24-h) collection of urine. These findings correspond with the
circadian rhythmicity of the urinary mercury excretion established by Vokac et al.
(1980). Our results are not entirely comparable with the findings of Roels et al.
(1987), as our case evidently involves a different type of occupational exposure to
HgO, and the U-Hg concentration in postshift samples was not corrected to
urinary creatinine. Both creatinine and specific gravity adjustments of U-Hg
concentration seem to be affected by urine volume (Araki et al. 1986), which is
very important in the evaluation of U-Hg concentration in urine samples
immediately after the hard work load.
5
Conclusion
Our results confirm that postexposure B-Hg concentration is a valid and reliable
indicator of individual internal doses received during the current and recent
intermittent type of exposure to various Hgo concentrations in air. Owing to the
fast elimination of Hg from blood, more attention should be focused on the
blood sampling time. Immediately after exposure, U-Hg seems to be predominantly dependent on the P-Hg level. At this type and level of exposure, U-Hg in
postshift samples, particularly if adjusted to a UV of 1 mllmin, reflect not only
the accumulation of mercury from earlier exposures but also the current group
level exposure. In individual evaluations the variation of U- Hg excretion in
postshift samples should be taken into account. The results of a Health Safety
Programme for miners intermittently exposed to Hgo in the Idrija mine (Kobal
1994; Kobal and Dizdarevic 1996) and applied over the last 25 years, confirm the
results obtained in our study.
In further validation of the biological threshold limit value for mercury
concentration in blood and urine in workers intermittently exposed to Hgo we
propose to take into account also the ratio between air-blood and blood-urine
mercury concentrations and the high interindividual variation in mercury
elimination in urine obtained in our investigation.
References
Araki S, Aono H, Murata K (1986) Adjustment of urinary concentration to urinary volume in relation
to erythrocytes and plasma concentrations: an evaluation of urinary heavy metals and organic
substances. Arch Environ Health 41:171-177
Barber TE, Wallis G (1986) Correction of urinary mercury concentration by specific gravity,
osmolality and creatinine. J Occup Med 28:354-359
Barregard L, Siillsten G, Schlitz A, Attewell R, Skerfving S, Jiirvholm B (1992) Kinetics of mercury in
blood and urine after brief occupational exposure. Arch Environ Health 47:176-184
A. Kobal et al.
correlated to plasma mercury, have a greater potential also for the estimation of
current group level exposure. Our results suggested that the average mercury
concentrations in the morning urine samples of the observed miners can replace
the 18-h (or 24-h) collection of urine. These findings correspond with the
circadian rhythmicity of the urinary mercury excretion established by Vokac et al.
(1980). Our results are not entirely comparable with the findings of Roels et al.
(1987), as our case evidently involves a different type of occupational exposure to
HgO, and the U-Hg concentration in postshift samples was not corrected to
urinary creatinine. Both creatinine and specific gravity adjustments of U-Hg
concentration seem to be affected by urine volume (Araki et al. 1986), which is
very important in the evaluation of U-Hg concentration in urine samples
immediately after the hard work load.
5
Conclusion
Our results confirm that postexposure B-Hg concentration is a valid and reliable
indicator of individual internal doses received during the current and recent
intermittent type of exposure to various Hgo concentrations in air. Owing to the
fast elimination of Hg from blood, more attention should be focused on the
blood sampling time. Immediately after exposure, U-Hg seems to be predominantly dependent on the P-Hg level. At this type and level of exposure, U-Hg in
postshift samples, particularly if adjusted to a UV of 1 mllmin, reflect not only
the accumulation of mercury from earlier exposures but also the current group
level exposure. In individual evaluations the variation of U- Hg excretion in
postshift samples should be taken into account. The results of a Health Safety
Programme for miners intermittently exposed to Hgo in the Idrija mine (Kobal
1994; Kobal and Dizdarevic 1996) and applied over the last 25 years, confirm the
results obtained in our study.
In further validation of the biological threshold limit value for mercury
concentration in blood and urine in workers intermittently exposed to Hgo we
propose to take into account also the ratio between air-blood and blood-urine
mercury concentrations and the high interindividual variation in mercury
elimination in urine obtained in our investigation.
References
Araki S, Aono H, Murata K (1986) Adjustment of urinary concentration to urinary volume in relation
to erythrocytes and plasma concentrations: an evaluation of urinary heavy metals and organic
substances. Arch Environ Health 41:171-177
Barber TE, Wallis G (1986) Correction of urinary mercury concentration by specific gravity,
osmolality and creatinine. J Occup Med 28:354-359
Barregard L, Siillsten G, Schlitz A, Attewell R, Skerfving S, Jiirvholm B (1992) Kinetics of mercury in
blood and urine after brief occupational exposure. Arch Environ Health 47:176-184