Evaluation of Internal Doses of Mercury at I ntermittent Exposure to Elemental Mercury
277
The correlation of HgO content in inhaled air with blood mercury is
exceptionally high and statistically significant (r = 0.96, P = 0.000). The
regression analysis showed that the ratio of HgO concentration in inhaled air to
total blood mercury (pg/m3: pgJl) at an air mercury level of 50 ~lg/m3 and
exposure of 4 h/day is 1:0.54, which partly corresponds to the ratio 1:0.49
obtained by Schaller and Triebig (1984), but not so well to the ratio 1:0.45
obtained by Roels et al. (1987) in workers who were long-term exposed to HgO for
about 8 h per day. On the basis of these relationships obtained in our study, it
can be concluded that intermittent exposure (4 h per day) to a HgO concentration
in air of 50 pg Hg/m3 results in a B-Hg concentration of 27 ~lg/l. At this level of
external exposure the B-Hg concentration obtained from Roels et al. (1987) was
22.6 ~lg/l. Despite the shorter daily exposure of the miners observed, the B-Hg
concentration is slightly higher, which is probably related to their higher
pulmonary ventilation (about 27 I of air per minute) during their work in the
mine.
The level of correlation of blood and urine mercury concentrations in miners
prior to exposure is in accordance with the results of Lauwerys and Buchet
(1973), who found the correlation at low blood mercury values (10 ~lg/l) to be low
(r = 0.36, P < 0.05, N = 40). Our postexposure results are very similar to the
findings of Schaller and Triebig (1984), who obtained a similar correlation
between blood and urine mercury in workers immediately after exposure to Hgo.
Our results also correspond to those of Nakaaki et al. (1975), as the mercury
concentration in urine increases significantly only during exposure to higher
concentrations.
Based on individual values obtained under our investigative conditions, it was
shown that the ratio between B-Hg (~lgJl) and U-Hg (~lg!l SG: 1.024) is 1:1.87 (for
external exposure to a HgO concentration of 50 pg/m3 - indirectly evaluated
data). On the basis of this ratio we can conclude that a B-Hg concentration of
27.21 pg/l results in a U-Hg concentration of 51 ~lg/I (SG: 1.024). Roels et al. (1987)
reported a ratio between B-Hg (pg/I) and U-Hg (pg/g creat) of 1:2.7, which
indicates higher values of U-Hg. The difference in the blood-urine mercury ratio
between the two investigations is in our opinion mostly related to the "type of
exposure". Roels et al. (1987) observed workers with long-term uninterrupted
exposure; on the other hand, we observed workers with long-term, but
interrupted and intermittent exposure. The ratio between air-Hg (~lg/m3) and
U-Hg (~lg/g creat) obtained by Roels et al. (1987) is 1:1.2. If we calculate our
results (from the relationship between air-blood and blood-urine mercury) the
ratio between air-Hg (~lg/m3) and U-Hg (pg/I SG: 1.024), is 1:1, which is expected
for the intermittent type of exposure in our study.
The regression analysis of postshift U-Hg concentrations and B-Hg
(y = 1.35x* + 14.3; * P < 0.001) showed a relatively high standard error of UHg prediction (sey = 37.7) from the blood mercury concentration, which clearly
indicates a high interindividual variation in Hg elimination in urine, depending
not only on the current exposure, but also on the accumulation of mercury in the
kidneys in earlier exposures.
The results obtained indicate that the urine samples collected immediately
postshift with the values adjusted to UV (1 mllmin), which were very good
277
The correlation of HgO content in inhaled air with blood mercury is
exceptionally high and statistically significant (r = 0.96, P = 0.000). The
regression analysis showed that the ratio of HgO concentration in inhaled air to
total blood mercury (pg/m3: pgJl) at an air mercury level of 50 ~lg/m3 and
exposure of 4 h/day is 1:0.54, which partly corresponds to the ratio 1:0.49
obtained by Schaller and Triebig (1984), but not so well to the ratio 1:0.45
obtained by Roels et al. (1987) in workers who were long-term exposed to HgO for
about 8 h per day. On the basis of these relationships obtained in our study, it
can be concluded that intermittent exposure (4 h per day) to a HgO concentration
in air of 50 pg Hg/m3 results in a B-Hg concentration of 27 ~lg/l. At this level of
external exposure the B-Hg concentration obtained from Roels et al. (1987) was
22.6 ~lg/l. Despite the shorter daily exposure of the miners observed, the B-Hg
concentration is slightly higher, which is probably related to their higher
pulmonary ventilation (about 27 I of air per minute) during their work in the
mine.
The level of correlation of blood and urine mercury concentrations in miners
prior to exposure is in accordance with the results of Lauwerys and Buchet
(1973), who found the correlation at low blood mercury values (10 ~lg/l) to be low
(r = 0.36, P < 0.05, N = 40). Our postexposure results are very similar to the
findings of Schaller and Triebig (1984), who obtained a similar correlation
between blood and urine mercury in workers immediately after exposure to Hgo.
Our results also correspond to those of Nakaaki et al. (1975), as the mercury
concentration in urine increases significantly only during exposure to higher
concentrations.
Based on individual values obtained under our investigative conditions, it was
shown that the ratio between B-Hg (~lgJl) and U-Hg (~lg!l SG: 1.024) is 1:1.87 (for
external exposure to a HgO concentration of 50 pg/m3 - indirectly evaluated
data). On the basis of this ratio we can conclude that a B-Hg concentration of
27.21 pg/l results in a U-Hg concentration of 51 ~lg/I (SG: 1.024). Roels et al. (1987)
reported a ratio between B-Hg (pg/I) and U-Hg (pg/g creat) of 1:2.7, which
indicates higher values of U-Hg. The difference in the blood-urine mercury ratio
between the two investigations is in our opinion mostly related to the "type of
exposure". Roels et al. (1987) observed workers with long-term uninterrupted
exposure; on the other hand, we observed workers with long-term, but
interrupted and intermittent exposure. The ratio between air-Hg (~lg/m3) and
U-Hg (~lg/g creat) obtained by Roels et al. (1987) is 1:1.2. If we calculate our
results (from the relationship between air-blood and blood-urine mercury) the
ratio between air-Hg (~lg/m3) and U-Hg (pg/I SG: 1.024), is 1:1, which is expected
for the intermittent type of exposure in our study.
The regression analysis of postshift U-Hg concentrations and B-Hg
(y = 1.35x* + 14.3; * P < 0.001) showed a relatively high standard error of UHg prediction (sey = 37.7) from the blood mercury concentration, which clearly
indicates a high interindividual variation in Hg elimination in urine, depending
not only on the current exposure, but also on the accumulation of mercury in the
kidneys in earlier exposures.
The results obtained indicate that the urine samples collected immediately
postshift with the values adjusted to UV (1 mllmin), which were very good