Excretion kinetics and variability of urinary mercury in workers exposed to mercury vapour

Summary Determinations of mercury in urine were made in samples collected from workers that were: (a) exposed prior to sampling — urine has been sampled over 3 weeks' post-exposure period; (b) currently exposed — sampling on consecutive days of the working week; (c) currently exposed —urine sampled over 24 hrs, during working shift (morning or afternoon) and off work.Mercury excretion in group (a) followed a two-term exponential equation with rate constants of about 0.35 and 0.01 day^–1. Regardless of exposure time pattern in all groups studied, a diurnal variation of urinary concentrations of mercury was observed with a maximum at night and morning hours, and minimal values in the afternoon. The great variability in Hg-concentrations could have been related to the time of day at which the sampling took place, and partly to variation of urine excretion rate, the 2 factors being interrelated. Only a moderate variability in urinary concentrations of mercury was found when the sampling was instituted at a constant time of day, and when the results were standardized for specific gravity of urine.Investigations supported in part by the Polish-American agreement 05-009-2 and 05-003-2 with NIOSH, USA.     

汞作业工人尿N-乙酰-β-D-氨基葡萄糖苷酶活性测定

目的 探讨汞接触工人尿N－乙酰－β－D氨基葡萄糖苷酶（NAG）活性。方法 对某灯泡厂接触不同浓度汞的77名工人进行尿NAG活性测定。并对车间空气汞浓度，尿汞含量，汞作业工龄的关系进行相关分析。结果 接汞组尿NAG活性明显高于对照组（P＜0．005）。尿NAG活性随环境空气汞浓度的增高而逐渐升高，并具有明显的剂量反应关系。但汞作业工龄与NAG之间无显著性（P＞0．05）。结论 在低浓度汞接触时，NAG活性增高较尿汞异常出现得早。建议将尿NAG活性作为汞接触人群健康监护指标之一，在职业健康监护体检中与尿汞同时进行检测。     

Enzymuria in workers exposed to inorganic mercury

Summary Urinary excretion of beta-hexosaminidase (NAG = N-acetyl-beta-glucosaminidase) and albumin was examined in 41 chlor-alkali workers exposed to inorganic mercury and 41 age-matched controls. Either U-HG or B-Hg levels for these workers were available dating from the 1960s to the present. Increased U-NAG was seen in workers with a U-Hg today of more than 4g/mmol creat (about 50g/l; 35 g/g creat). Multiple linear regression analysis showed that U-NAG was correlated to U-Hg and integrated dose but not to the present B-Hg level. No albuminuria (detection limit 12.5 mg/1) was found in any of the subjects. In a longitudinal study, no decrease in UNAG levels was seen in 15 chlor-alkali workers after their vacation (x = 20 d). In five workers followed for ten months after a short exposure period, no definite time trend could be seen. The results show that there is a slight effect on renal tubules even at rather low levels of exposure to mercury vapour. The clinical significance of the enzymuria levels found here is, however, debatable.     

Elemental mercury in urine from workers exposed to mercury vapor

Summary Elemental mercury (Hg°) in urine samples from workers in thermometer manufacturing factories was determined. In a factory in which the mercury level in the ambient air averaged more than 0.1 mg Hg m^–3, the Hg° concentration in the workers' urine ranged between 0.05 and 1.7 g Hg 1^–1 and constituted less than 1% of the inorganic mercury (In-Hg) in urine. Higher amounts of Hg° could be detected in urine on the day of the filling operation when thermometer blanks were filled with metallic mercury and on the following day when compared with other days. During this operation, the workers were exposed to mercury vapor levels with as much as 0.47–0.67 mg Hg m^–3. Our findings suggest that Hg° appears in urine quite rapidly after the worker's exposure to unusually high mercury levels.     

Electroneurographic findings in workers exposed to mercury]

25 mercury-exposed workers as well as 27 age-matched controls were investigated in an electroneurographic study. The population of mercury-exposed workers was found to have --an increased latency of distal motor action potential at both median and peroneal nerves --an increased latency of distal sensory action potential at median nerve --a decrease of amplitudes of evoked muscle potentials at both median and peroneal nerves --a reduced motor nerve conduction velocity at both examined nerves --a reduced antidromic sensory nerve conduction velocity at median nerve. To detect early changes in nerval function we recommend regularly electroneurographic examinations of mercury-exposed people.     

Ocular disorders among workers exposed to mercury

Mercury vapor exposed workers may show ocular changes, as well as other systems affection. A sample of 84 workers in preparing mercury fulminate were examined for conjunctival corneal and lenticular manifestation of long duration exposure, together with mercury urinary output. Lens changes were found in 50% of the involved workers while keratopathy as recorded in 34.5% of them. No statistically significant association was found between the occurrence of eye lesions and levels of urinary elimination of mercury. These results suggest local absorption of this element is most probably the underlying cause of ocular affection.     

Urinary N-acetyl-beta-D-glucosaminidase in workers exposed to the effects of mercury

Mercury concentration in urine and urinary activity of N-acetyl-beta-D-glucosaminidase were determined in a group of 100 workers from an electrolysis workshop. The enzyme activities measured were twice as high as those of 100 control subjects. The difference was statistically significant. There was no correlation between urinary activity of N-acetyl-beta-D-glucosaminidase and mercury concentration in urine. The applicability of this biochemical-toxicological test in occupational health practice is discussed.     

Visual field losses in workers exposed to mercury vapor

Visual field losses associated with mercury (Hg) exposure have only been assessed in patients exposed to methylmercury. Here we evaluate the automated visual field in 35 ex-workers (30 males; 44.20+/-5.92 years) occupationaly exposed to mercury vapor and 34 controls (21 males; 43.29+/-8.33 years). Visual fields were analyzed with the Humphrey Field Analyzer II (model 750i) using two tests: the standard automated perimetry (SAP, white-on-white) and the short wavelength automated perimetry (SWAP, blue-on-yellow) at 76 locations within a 27 degrees central visual field. Results were analyzed as the mean of the sensitivities measured at the fovea, and at five successive concentric rings, of increasing eccentricity, within the central field. Compared to controls, visual field sensitivities of the experimental group measured using SAP were lower for the fovea as well as for all five eccentricity rings (p<0.05). Sensitivities were significantly lower in the SWAP test (p<0.05) for four of the five extra-foveal eccentricity rings; they were not significant for the fovea (p=0.584) or for the 15 degrees eccentricity ring (p=0.965). These results suggest a widespread reduction of sensitivity in both visual field tests. Previous reports in the literature describe moderate to severe concentric constriction of the visual field in subjects with methylmercury intoxication measured manually with the Goldman perimeter. The present results amplify concerns regarding potential medical risks of exposure to environmental mercury sources by demonstrating significant and widespread reductions of visual sensitivity using the more reliable automated perimetry.     

Peripheral neurotoxicity in workers exposed to inorganic mercury compounds

Nerve conduction velocity (NCV) of the median motor, median sensory, and sural nerves was assessed in 16 workers chronically exposed to various inorganic mercury compounds. Exposed workers were compared with an unexposed control group using t test analyses. Slowing of the median motor nerve NCV was found, which was correlated with both increased levels of mercury in blood and urine, and with increased number of neurologic symptoms. Sensitive evaluation of neural function was found to be practical and informative for investigating mercury toxicity. Such evaluation can help determine safe mercury levels at the workplace.     

Urinary markers of workers chronically exposed to mercury vapor

The effects of chronic mercury intoxication on urinary markers in workers from northeast Algeria were investigated. Workmen were chosen from highly and moderately mercury-exposed factories, while controls were selected from a nonexposed site. The number of proteinuria cases were higher in the highly exposed subjects, although the nature (glomerular or tubular) of proteinuria remains unclear. However, it appears difficult to assess the degree of renal disturbance among the different exposure levels, such as the amount of excreted proteins, which have not clearly reflected the kidney lesion severity. The results also reveal that urine acidity increased progressively with increased levels of exposure, while a remarkable inverse relationship between urinary pH and urinary Hg in the highly exposed workers has been recorded. Furthermore, the significant differences in blood and urinary mercury concentrations of the three sites reflect the dose-response relationships.     

Significance of urinary metallothionein in workers exposed to cadmium

Summary Cadmium in blood (Cd-B) and in urine (Cd-U) and metallothionein (Mt-U) and ₂-microglobulin in urine ( ₂m-U) were measured in 94 male Cd workers. The results were examined according to the workers' current exposure to cadmium (group C, n=73, workers currently exposed to Cd; group R, n=21, Cd workers removed from exposure or retired) and according to their renal status (group N, n=66, normal ₂m-U; group 1, n=28, ₂m-U>200 g/g creatinine). The interrelationships between Mt-U, Cd-U, Cd-B and years of cadmium exposure were examined in the various subgroups. The study of the correlations between these variables demonstrates that Mt-U is directly correlated with Cd-U but not with Cd-B or years of Cd exposure. The association between Cd-U and Mt-U is independent of the status of renal function and the intensity of current exposure to cadmium. Under moderate chronic exposure to cadmium, the fraction of Cd-U which is directly influenced by recent exposure (Cd-B) is small in comparison with that influenced by the cadmium body burden.     

Urinary mercury excretion and body weight on workers exposed to mercury vapour

Summary From the 5-year record of health checks including urinary mercury levels and body weights on 33 workers exposed to mercury vapour in a tungsten rod manufacturing factory, the relationships between the level of urinary mercury and the body weight, and between the change of urinary mercury levels and that of body weights, were analysed. Except for the workers with the short period of exposure, on whom no significant correlation was found, correlations between the changes; urinary mercury and body weight, were much stronger than those between the levels. In contrast to the significant negative correlations in the mentioned relationships on the workers with the long period of continuous exposure at atmospheric concentrations below 0.2 mg/m³, there was significant positive correlations on the workers with occasional, short-period exposures at much lower concentrations of mercury. The importance of analysis on the change of exposure and its relation to the effect was emphasized, and possible effects of mercury to the regulation of body weight was discussed.     

噪声作业对工人心电图检查结果影响研究

目的探讨接触噪声对工人心电图的影响.方法用心电图诊断仪,检查作业工人在静息状态下心电图九导联,发现异常病变及有特殊需要时加作V2、V4、V6导联.结果观察组心电图异常检出率与对照组比较差异有显著性,异常主要引起窦性心动过缓,其检出率与对照组比较差异有显著性.结论噪声可对心血管系统造成损害,引起血压升高、心电图改变等.应尽快制订相关的法律法规,保护广大产业工人的身体健康.     

接汞工人甲状腺功能的观察

本文用放射免疫分析法及临床检查法调查研究了沈阳某灯泡厂长期接触汞作业工人57名,接汞平均工龄8.5年。同时选择与该厂条件相近,非接汞和其它毒物的某厂工人36名为对照组。观察结果表明,汞确能引起接汞工人血清甲状腺素水平及类似甲状腺功能亢进的症状和体征的发生率显著高于对照组。据此认为,长期接汞工人甲状腺功能高于正常人。     

Cytogenetic examination of leucocytes of workers exposed to mercury vapour

Summary Cytogenetic observations have been performed on male subjects occupationally exposed to elemental mercury in a plant where mercury is amalgamated with zinc and in a chloralkali plant [n=22; average level of mercury in urine was 117 g/g creatinine and of mercury in blood 3.1 g/100 ml; mean duration of Hg exposure 4 years (range: 0.3–15.3)]. The exposure to mercury vapour did not result in an increased yield of structural chromosomal aberrations in peripheral blood lymphocytes of the workers. These negative results are in agreement with the findings reported for other eukaryotic systems and confirm that population monitoring based on cytogenetic examination of peripheral blood lymphocytes does not always represent a good indicator of damage to genetic material produced by a chemical.     

职业接触汞工人肾脏早期损伤指标的探讨

目的　探讨职业接触汞工人肾损伤的早期监控指标。方法　尿汞 (HgU)采用二硫腙化学法测定 ,尿视黄醇结合蛋白 (RBP)、尿 β2 微球蛋白 (β2 MG)和尿微量白蛋白 (mALB)采用全定量酶免疫法测定 ,尿N 乙酰 β D 氨基葡萄糖苷酶 (NAG)和γ 谷氨酰基转移酶 (γ GT)采用速率法测定 ,尿肌酐(Cr)采用苦味酸法测定。结果　职业接触汞工人尿RBP、β2 MG、NAG、γ GT测定结果分别为 (4 39.7±2 0 1.4 )、(14 1.4± 5 6 .3) μg gCr,(12 .3± 5 .7)、(6 0 .3± 18.5 )U gCr,均高于对照组 [分别为 (2 4 3.2±16 9.1)、(88.6± 4 1.2 ) μg gCr,(8.2± 1.6 )、(4 1.3± 13.2 )U gCr],差异均有显著性 (P <0 .0 5 ,P <0 .0 1)。随尿汞含量增加上述指标有逐渐增高的趋势 ;单项及两项检测RBP、β2 MG、NAG、γ GT的阳性率较低 ,联合其中 3项检测阳性率较高 ,联合 4项检测阳性率可达 85 .5 %。结论　联合检测RBP、β2 MG、NAG、γ GT是诊断职业接触汞工人早期肾损伤的灵敏指标。     

Endocrine function in mercury exposed chloralkali workers.

OBJECTIVE--The aim was to study whether functional impairment of the pituitary, thyroid, testes, and adrenal glands of humans occupationally exposed to mercury (Hg) vapour can be shown as a result of accumulation of Hg in these glands. METHODS--Basal concentrations of thyrotrophin (TSH), prolactin, free thyroxine (free T4), free 3,5,3'-triiodothyronine (free T3), antibodies against thyroperoxidase, and testosterone in serum, as well as cortisol in morning urine were measured in 41 chloralkali workers exposed (10 years on average) to Hg vapour, and in 41 age matched occupationally unexposed referents. The chloralkali workers had a mean urinary Hg concentration (U-Hg) of 15 nmol/mmol (27 micrograms/g) creatinine, and a mean blood Hg concentration (B-Hg) of 46 nmol/l. For the reference group U-Hg and B-Hg were 1.9 nmol/mmol (3.3 micrograms/g) creatinine and 17 nmol/l respectively. RESULTS--The serum free T4 concentration and the ratio free T4/free T3 were slightly, but significantly, higher in the subgroups with the highest exposure, and the serum free T3 was inversely associated with cumulative Hg exposure. This indicates a possible inhibitory effect of mercury on 5'-deiodinases, which are responsible for the conversion of T4 to the active hormone T3. Serum total testosterone, but not free testosterone, was positively correlated with cumulative Hg exposure. Prolactin, TSH and urinary cortisol concentrations were not significantly associated to exposure. CONCLUSION--Apart from inhibition of the deiodination of T4 to T3, the endocrine functions studied seem not to be affected by exposure to Hg vapour at the exposure levels of the present study. Growth hormone secretion was not studied.     

Mortality and cancer incidence in chloralkali workers exposed to inorganic mercury

Mortality and cancer incidence were studied in men exposed to inorganic mercury at eight Swedish chloralkali plants where individual biological monitoring data were available. Urinary mercury excretion has declined from about 200 micrograms/l during the 1950s to less than 50 micrograms/l today. These workers had also been exposed to chlorine and static magnetic fields. At some of the plants there had been a low degree of exposure to asbestos. In total, 1190 men had been monitored for at least one year between 1946 and 1984. Their mortality and cancer incidence were compared with those of the general male population. Mortality from all causes was not significantly increased (rate ratio = 1.1). Cardiovascular mortality was slightly increased (rate ratio = 1.3; 95% CI 1.0-1.5) for no known reason. An excess of lung tumours was seen (rate ratio = 2.0; 95% CI 1.0-3.8), possibly caused by previous exposure to asbestos. Mortality from non-malignant diseases of the brain and the kidneys, the main target organs in mercury poisoning, was not increased, nor was the incidence of brain tumours (3 observed v 1.1 expected) or kidney tumours (3 observed v 1.9 expected).