Urinary Mercury Levels Research Articles

Immunoglobulin E and Autoantibodies in Mercury-Exposed Workers

In this work we have studied the serum immunoglobulin E (IgE) levels and the concentration of anti-DNA and anti-nucleus antibodies in mercury-exposed workers. The study group consisted of 36 workers from a mercury producing plant, with a mean age of 27 years and a mean exposure period to mercury of 19 months. At the time of testing, and for the three previous months, the exposed population had urinary mercury levels below the currently accept limit of 50 ug/ g creatinine.Significantly increased IgE levels was found in the mercury-exposed individuals. Moreover, a moderate negative correlation (r = -0.43 P < 0.05) between the length of exposure to mercury and IgE levels was observed. Anti-DNA and anti-nucleus antibodies were not detected in these workers.These results suggest that the humoral immune response is an indicator of cellular changes in workers chronically exposed to mercury, even in those with urinary mercury concentrations within levels considered safe in the occupational area.

T Lymphocytes in Mercury-Exposed Workers

In this work we have investigated the changes in T-helper and T-suppressor cells and T-cell proliferative response to phytohemagglutinin (PHA) in mercury-exposed workers. The study group consisted of 33 workers from a mercury-producing plant with a mean age of 29 years and a mean exposure period of 19 months. At the time of testing, and for the three previous months, the exposed population had urinary mercury levels below the currently accepted limit of 50 ug/g creatinine.A reverse CD4+/CD8+ ratio was observed in the mercury-exposed individuals which was characterized by a reduction in the number of CD4+ lymphocytes. No changes were observed in the proliferative response of lymphocytes from exposed individuals to PHA. Similarly, no proliferative response was observed when lymphocytes from normal individuals were cultivated in the presence of serum from the exposed workers. We found no correlations between lymphocytes changes and urinary mercury concentrations, time of exposure or the age of the workers.

Monitoring of fish and human exposure to mercury due to gold mining in the Lake Victoria goldfields, Tanzania

Monitoring of environmental and human exposure to mercury in the Nungwe Bay area of the Lake Victoria goldfields. Tanzania, has revealed low mercury concentrations in fish (range: 1.8–16.9 ppb, mean: 7.0 ppb) and human hair (range: 156–5433 ppb, mean: 947 ppb) that represent background levels. Gold mining has not produced a significant increase in environmental methylmercury that is available for bioaccummulation in aquatic food chains. Urinary mercury levels in gold mine workers frequently exposed to Hg vapour in amalgamation and burning of amalgam were significantly higher (mean: 241 ng/ml) than those in the general mine population not occupational exposed to Hg (mean: 2.6 ng/ml). Rotation of mine duties reduced Hg exposure levels and hence the risk of intoxication in the gold mine workers. The lowest urinary and hair mercury levels were found in the Nungwe Bay fishing village population. This was consistent with the low mercury content of fish consumed by the inhabitants of the Nungwe Bay.

Urinary mercury levels before and after amalgam restoration

Urinary mercury levels and excretion rates were measured to determine the effect of dental amalgam restoration on the mercury body burden. No consistent increase in urinary mercury concentrations was found among subjects who had a single restoration, but a continuously increasing statistically significant (P < 0.05) trend, that was 33% above background levels, was detected between 9 and 12 days after restoration, in the subject with four restorations in a single day. The current findings suggested that even though amalgam restorations can cause an increase in mercury body burden, the elevation above background levels is small and thus the risks associated with the use of this material are considered minimal for the general population.

Mercury vapor release from dental amalgam in patients with symptoms allegedly caused by amalgam fillings.

The aim of this study was to determine whether a group of patients with symptoms, self-related to their amalgam restorations, experienced an exposure to mercury vapor from their amalgam restorations that reached the range at which subtle symptoms have been reported in the literature. Furthermore, the aim was to determine whether the mercury exposure for these patients was significantly higher than for controls with no reported health complaints. The symptom group consisted of 10 consecutively selected patients from a larger group, referred by their physicians for investigation into any correlation between subjective symptoms and amalgam restorations. The control group consisted of 8 persons with no reported health complaints. The intra-oral release of mercury vapor was measured between 7:45 a.m. and 9:00 p.m. at intervals of 30-45 min, following a standardized schedule. The mercury levels in plasma, erythrocytes, and urine were also determined. The calculated daily uptake of inhaled mercury vapor, released from the amalgam restorations, was less than 5% of the daily uptake calculated at the lower concentration range given by the WHO (1991), at which subtle symptoms have been found in particularly sensitive individuals. The symptom group had neither a higher estimated daily uptake of inhaled mercury vapor, nor a higher mercury concentration in blood and urine than in the control group. The study provides no scientific support for the belief that the symptoms of the patients examined originated from an enhanced mercury release from their amalgam restorations.

Long-term use of nicotine chewing gum and mercury exposure from dental amalgam fillings.

In experimental studies, chewing gum has been shown to increase the release rate of mercury vapor from dental amalgam fillings. The aim of the present study was to investigate the influence of long-term frequent chewing on mercury levels in plasma and urine. Mercury levels in plasma (P-Hg) and urine (U-Hg), and urinary cotinine were examined in 18 subjects who regularly used nicotine chewing gum, and in 19 referents. Age and number of amalgam surfaces were similar in the two groups. Total mercury concentrations in plasma and urine were determined by means of cold vapor atomic absorption spectrometry. Urinary cotinine was determined by gas chromatography-mass spectrometry. The chewers had been using 10 (median) pieces of gum per day for the past 27 (median) months. P-Hg and U-Hg levels were significantly higher in the chewers (27 nmol/L and 6.5 nmol/mmol creatinine) than in the referents (4.9 nmol/L and 1.2 nmol/mmol creatinine). In both groups, significant correlations were found between P-Hg or U-Hg on the one hand and the number of amalgam surfaces on the other. In the chewers, no correlations were found between P-Hg or U-Hg and chewing time per day or cotinine in urine. Cotinine in urine increased with the number of pieces of chewing gum used. The impact of excessive chewing on mercury levels was considerable.

Altered porphyrin metabolism as a biomarker of mercury e×posure and to×icity

Changes in urinary porphyrin excretion patterns (porphyrin profiles) have been described in response to a variety of drugs and chemicals. The present studies were conducted to define the specific changes in the urinary porphyrin profile associated with prolonged exposure to mercury and mercury compounds. In rats, exposure for a prolonged period to mercury as methyl mercury hydroxide was associated with urinary porphyrin changes, which were uniquely characterized by highly elevated levels of 4- and 5-carboxyl porphyrins and by the expression of an atypical porphyrin ("precoproporphyrin") not found in urine of unexposed animals. These distinct changes in urinary porphyrin concentrations were observed as early as 1-2 weeks after initiation of mercury exposure, and increased in a dose- and time-related fashion with the concentration of mercury in the kidney, a principal target organ of mercury compounds. Following cessation of mercury exposure, urinary porphyrin concentrations reverted to normal levels, consistent with renal mercury clearance. In human studies, a comparable change in the urinary porphyrin profile was observed among subjects with occupational exposure to mercury as mercury vapor sufficient to elicit urinary mercury levels greater than 20 micrograms/L. Urinary porphyrin profiles were also shown to correlate significantly with mercury body burden and with specific neurobehavioral deficits associated with low level mercury exposure. These findings support the utility of urinary porphyrin profiles as a useful biomarker of mercury exposure and potential health effects in human subjects.

High hair and urinary mercury levels of fish eaters in the nonpolluted environment of Papua New Guinea.

Hair and mercury concentrations of 134 fish-eating subjects in the Lake Murray area and 13 non-fish-eating subjects in the upper-Strickland area, Papua New Guinea, were studied. Hair mercury levels among the subjects in the Lake Murray area (mean = 21.9 micrograms/g, range = 3.7-71.9 micrograms/g) and urinary mercury levels (mean = 7.6 micrograms/g creatinine, range = 1.4-25.6 micrograms/g creatinine) were markedly higher than levels found in subjects from the upper-Strickland area (mean hair mercury = 0.75 micrograms/g, mean urinary mercury = 0.48 micrograms/g creatinine). Mercury intake of the fish eaters, estimated from mercury concentrations found in fish and from the observed amounts of fish consumed, was approximately 73 micrograms/d. Hair and urinary mercury concentrations were correlated significantly (r = .59), indicating that urinary mercury excretion was elevated because fish consumption was very high.

Diagnosis of health conditions in a pan-mining community in the Tapajós River Basin, Itaituba, Par , Brazil, 1992

The purpose of this article is to describe health conditions in a pan-mining community, in particular the interaction of mercury contamination with other health problems. This study was carried out in a panning mine located on Rato Creek, a tributary of the Tapajó s River Basin in the municipality of Itaituba, State of Par The study population consisted of 223 individuals. An epidemiological questionnaire was applied, medical treatment was given, and biological specimens were collected. Testing of fecal samples showed that 96.1% of the individuals had parasites and 66.4% were anemic. Prevalence of hepatitis B virus was 85.0%, and 11 individuals (6.0%) were virus carriers (HBsAg positive). Of 186 patients tested for malaria, 65 individuals (35.0%) had the infection, of whom 34 (52.3%) were asymptomatic. Prevalence of syphillis was 41.6%. Urine mercury levels were measured in 173 individuals. Some 16 (9.2%) of those tested had mercury levels between 10 and 19 ug/l, while 9 patients (5.2%) had levels above 20 ug/l. An overview of general health conditions showed a combination of problems in individuals, who lacked adequate diagnosis, in addition to a high level of self-medication, given the absence of health facilities. In addition, these individuals are threatened by critical levels of mercury contamination. In conclusion, this article gives a general overview of health conditions in these pan-mining communities, demonstrating the multicausal nature of health conditions in the Amazon region, a fact which should be considered when planning appropriate strategies for clinical treatment.

In vivo XRF analysis of mercury: the relation between concentrations in the kidney and the urine

The objective of this study was to determine the concentrations of mercury in organs of occupationally exposed workers using in vivo X-ray fluorescence analysis. Twenty mercury exposed workers and twelve occupationally unexposed referents participated in the study. Their mercury levels in kidney, liver and thyroid were measured using a technique based on excitation with partly plane polarized photons. The mercury levels in blood and urine were determined using atomic absorption spectrophotometry. The detection limit for mercury in the kidney was exceeded in nine of the exposed workers, but in none of the referents. The mean kidney mercury concentration (including estimates below the detection limits) was 24 mu g g-1 in the exposed workers, and 1 mu g g-1 in the referents. The association between mercury in the kidney and in urine was statistically significant, but it was unclear whether the relation was linear. The measurements on liver (n=10) and thyroid (n=8) in the exposed workers showed mercury levels below the detection limit. The study shows that it is now possible to measure the mercury concentrations in kidneys of occupationally exposed persons, using in vivo X-ray fluorescence. The estimated concentrations are in reasonable agreement with the limited human autopsy data, and the results of animal studies.

Measurement of the respiratory burst and chemotaxis in polymorphonuclear leukocytes from mercury-exposed workers.

The chemotactic and nitroblue tetrazolium reducing activities of neutrophils from 48 mercury-exposed workers were examined and compared with those of non-exposed, age- and sex-matched individuals. At the time of testing, the exposed population had a mean (+/- s.d.) urinary mercury concentration of 24.0 +/- 20.1 micrograms g-1 creatinine and in 44 of these workers urinary mercury levels were below the accepted threshold level (TLV) of 50 micrograms g-1 creatinine. The two neutrophil functions were significantly reduced in the mercury-exposed workers compared with the controls. In 28 of these workers, chemotaxis was re-evaluated 6 months later. During the intervening 6 months, the level of hygiene was improved throughout the plant and urinary mercury concentrations were determined monthly in each worker. Despite a significant reduction in urinary mercury concentrations, neutrophil migration did not return to within the normal range. These results suggest that 'safe' level mercury exposure may lead to impairment of neutrophil function.

Subclinical neurotoxicity of mercury vapor revealed by a multimodality evoked potential study of chloralkali workers

Pattern visual, brainstem auditory, and somatosensory evoked potential (EP) studies were performed on 26 chloralkali workers. The intensity of mercury vapor exposure in these workers was estimated from the individual working history. Mercury levels in blood, urine, and hair were determined with atomic absorption spectrometry. The EP findings were compared with those from individually matched normal subjects. In brainstem auditory and somatosensory EP studies, prolonged neural conduction times in the central nervous system (CNS) were found in workers exposed to mercury vapor. In the pattern visual EP study, mercury workers had higher interpeak amplitudes. Findings of this study suggested that chronic exposure to mercury vapor would affect the CNS functions. A multimodality EP study is a useful adjunct in evaluation of chronic mercury neurotoxicity, especially in an epidemiological study.

Fractional Mercury Levels in Brazilian Gold Refiners and Miners

A field study survey of individuals residing in the region of Para, Brazil, was conducted to determine fractional mercury levels in individuals at risk for exposure in the Brazilian Amazon region. Subjects with a history of exposure to mercury either in the gold mining or refining industry, or exposure to these processes through proximity were included. Three groups were identified as either having recent (less than 2 d since last exposure), intermediate (less than 60 d), or remote (greater than 60 d) exposure to mercury vapors. Fractional blood and urinary mercury levels were assessed for these groups. Group I (recent) had the highest geometric mean blood 24.8 (SD 44.1, range 7.6-158.8) micrograms/L and urine 75.6 (SD 213.4, range 6.5-735.9) micrograms/g-cr (microgram mercury per gram of creatinine) mercury; intermediate (group II) geometric mean blood 7.6 (SD 5.5, range 2.2-19.4) micrograms/L and urine levels 23.8 (SD 84.0, range 7.8-297.0) micrograms/g-cr; the lowest levels in remote exposure (group III): geometric mean blood 5.6 (SD 3.3, range 3.1-14.3) micrograms/L and urine 7.0 (SD 9.8, range 3.1 to 32.9) micrograms/g-cr. The fraction of organic was lowest in group I (32.4%), higher in group II (65.7%), and highest in group III (72.2%). While the frequency of symptoms was comparable in the recent and intermediate groups (2.6 mean, SD 2.3, range 0-8, and 3.1 mean, SD 1.9, range 0-7, symptoms per patient), those with remote exposure demonstrated the highest rate of reporting (6.4 mean, SD 4.1, range 0-11, symptoms per patient). There is significant exposure to mercury for those working in or living near the mining and refining industry. Blood and urine levels are a better marker of recent than remote exposure. The fraction of organic mercury increases with time since exposure. Symptoms may be persistent and low levels of blood and urine mercury do not exclude remote or cumulative toxicity.

Long-term mercury excretion in urine after removal of amalgam fillings.

The long-term urinary mercury excretion was determined in 17 28- to 55-year-old persons before and at varying times (up to 14 months) after removal of all (4-24) dental amalgam fillings. Before removal the urinary mercury excretion correlated with the number of amalgam fillings. In the immediate post-removal phase (up to 6 days after removal) a mean increase of 30% was observed. Within 12 months the geometric mean of the mercury excretion was reduced by a factor of 5 from 1.44 micrograms/g (range: 0.57-4.38 micrograms/g) to 0.36 microgram/g (range: 0.13-0.88 microgram/g). After cessation of exposure to dental amalgam the mean half-life was 95 days. These results show that the release of mercury from dental amalgam contributes predominantly to the mercury exposure of non-occupationally exposed persons. The exposure from amalgam fillings thus exceeds the exposure from food, air and beverages. Within 12 months after removal of all amalgam fillings the participants showed substantially lower urinary mercury levels which were comparable to those found in subjects who have never had dental amalgam fillings. A relationship between the urinary mercury excretion and adverse effects was not found. Differences in the frequency of effects between the pre- and the post-removal phase were not observed.

Immunoglobulin Levels in Workers Exposed to Inorganic Mercury

The serum immunoglobulin (IgG, IgM and IgA) concentrations of 44 mercury-exposed workers were examined and compared with those of non-exposed, age- and sex-matched individuals. At the time of testing, the exposed population had a mean (+/- S.D.) mercury urinary concentration of 24.7 +/- 19.1 and in 40 of them urinary mercury levels were below the currently accepted limit of 50 micrograms/g creatinine. Increased IgG, IgA and IgM levels were found in the mercury-exposed individuals and in 16, a second evaluation was performed six months later. During the intervening six months, the level of hygiene was improved throughout the plant, and urinary mercury concentrations were determined monthly in each worker. Despite a significant reduction in mercury urinary concentrations, serum immunoglobulin levels did not return to the normal range. There was no correlation between the length or level of exposure and the immunoglobulin levels. Liver protein synthesis, as studied by factor V, prothrombin time, prealbumin and transaminase activity, was normal and liver injury, as evaluated by serum aspartate and alanine aminotransferase activities (AST and ALT, respectively), was not observed. No haematological abnormalities were noted. These results indicate that "safe" levels of mercury exposure may lead to humoral immunological stimulation.

Effect of mercury from dental amalgams on mercury concentration in urine.

A study was conducted to determine the mercury concentration in urine after placement of dental amalgam restorations. The 24-h urine mercury levels in 10 children with a mean age of 8 years were determined before the amalgam restorations had been placed, and after placement. The urinary mercury content was measured by the cold vapor atomic fluorescence method. Mercury levels in the urine samples before placement of the amalgam restorations were below the detection limit, and the values obtained after placement, although detectable, were far below the limits stipulated by the World Health Organization. Under the conditions of this study, it is considered that the mercury levels released from dental amalgams are not high enough to cause any systemic toxic effect.

Urinary mercury level in Japanese school children: influence of dental amalgam fillings and fish eating habits

The influence of dental amalgam fillings and fish eating frequency on the urinary mercury (Hg) level was evaluated in 1642 children (ages: 3–18) living in Tokyo. Geometric mean of the urinary Hg level was 1.9 μg Hg/l and 1.9 μg Hg/g creatinine (Cr) for boys and 2.1 μg Hg/l and 2.0 μ Hg/g Cr for girls. Multiple regression analysis was conducted using: (1) urinary Cr concentration (only in the case of urinary Hg expressed as μg Hg/l); (2) age; (3) gender; (4) number of dental amalgam fillings; and (5) fish eating frequency as independent variables. As a result, all the variables examined were significant and the explanatory powers (square of multiple correlation coefficient) of these variables were 17 or 7% for urinary Hg expressed as μg Hg/l or μg Hg/g Cr, respectively. Number of dental amalgam fillings or fish eating frequency explained only up to 1.5% of the total variance of urinary Hg. Contribution of Cr concentration, age and gender to urinary Hg level is also discussed.

Abstract #14 — Blood and urine mercury levels following retrograde amalgams in primates

Abstract #14 — Blood and urine mercury levels following retrograde amalgams in primates

Self-injection with mercury

A 27.year-old doorman at a local hotel casino presented to the accident and emergency department in December 1991. He complained of a painful swelling on the flexor aspect of his forearm. Examination revealed a tender 4 x 5 cm fluctuant swelling. There were no local puncture sites or wounds. The ‘abscess’ was incised under local anaesthesia. The doctor was surprised when mercury was drained. A forearm radiograph showed more mercury in the wound (Figure I), and a chest radiograph demonstrated mercuric emboli throughout both lungs (Figure 2). Over the next 2 months serial measurements of blood and urine mercury levels were raised, but not to toxic levels. Respiratory function tests were normal and 24 h urine collection revealed normal creatinine clearance. At 1 week after presentation the mercuric swelling on his right forearm was completely excised and closed primarily, under general anaesthesia. At I month after presentation he attended the department complaining of flu-like symptoms and headache. A skull radiograph then showed specks of mercury, suggesting the possibility of intracranial deposits implying that the mercury had passed through his lungs to the systemic circulation. He was given penicillamine. He remained well and continued to revel in the medical attention and to deny all knowledge of how the mercury had entered his body! He is a keen body builder of 1.90 m in height and weighs 107 kg. He says his occupation demands a certain stature and strength. In February 1992 he again presented to the accident and emergency department, on this occasion with a bullet wound on his forehead. Computerized tomography demonstrated a large frontal haematoma and he was referred to the neurosurgeons for wound excision and retrieval of a hand gun bullet. He declined to describe how either incident had occurred.

Evaluation and Control of Mercury Vapor Exposure in the Cell House of Chlor Alkali Plants

A pilot study was carried out in the cell houses of three chlor alkali plants to assess level of exposure to mercury vapors among workers by air and biological monitoring. Overall airborne mercury concentrations (mg/m3) were found to range from 0.05 to 0.42 (mean, 0.21, n = 68). 0.03 to 0.16 (mean, .08. n = 49), and 0.02 to 0.17 (mean, 0.04, n = 26), whereas urinary mercury levels (mg/liter) of the exposed workers of the respective plants ranged from 0.076 to 0.592 (mean, 0.207, SD, 0.107, n = 19), 0.015 to 0.220 (mean, 0.070, SD, 0.054, n = 16), and 0.013 to 0.275 (mean, 0.06, SD, 0.054, n = 23). Unattended mercury spillage on the floor and improper sealing of the lids of the end boxes of electrolysis cells were found to be main factors attributing to prevalence of mercury vapors in excess of the permissible exposure limit of 0.05 mg/m3. Based on the deficiencies observed, appropriate control measures have been suggested to reduce airborne mercury vapor concentrations in the work environment.