Long-term loss of color vision after exposure to mercury vapor

We evaluated the color vision of 24 subjects (41.6 ± 6.5 years; 6 females) who worked in fluorescent lamp industries. They had been occupationally exposed to mercury vapor (10.6 ± 5.2 years) and had been away from the source of exposure for 6.4 ± 4.04 years. Mean urinary concentration of mercury was 40.6 ± 36.4 µg/g creatinine during or up to 1 year after exposure and 2.71 ± 1.19 µg/g creatinine at the time of color vision testing or up to 1 year thereafter. All patients were diagnosed with chronic mercury intoxication, characterized by clinical symptoms and neuropsychological alterations. A control group (N = 36, 48.6 ± 11.9 years, 10 females, 1.5 ± 0.47 µg mercury/g creatinine) was subjected to the same tests. Inclusion criteria for both groups were Snellen VA 20/30 or better and absence of known ophthalmologic pathologies. Color discrimination was assessed with the Farnsworth D-15 test (D-15) and with the Lanthony D-15d test (D-15d). Significant differences were found between the two eyes of the patients (P < 0.001) in both tests. Results for the worst eye were also different from controls for both tests: P = 0.014 for D-15 and P < 0.001 for D-15d. As shown in previous studies, the D-15d proved to be more sensitive than the D-15 for the screening and diagnosis of the color discrimination losses. Since color discrimination losses were still present many years after the end of exposure, they may be considered to be irreversible, at least under the conditions of the present study.

Neuropsychological dysfunction related to earlier occupational exposure to mercury vapor

We assessed the neuropsychological test performances of 26 patients (mean age = 41.5 ± 6.1 years; mean years of education = 9.8 ± 1.8; 20 males) diagnosed with chronic occupational mercurialism who were former workers at a fluorescent lamp factory. They had been exposed to elemental mercury for an average of 10.2 ± 3.8 years and had been away from this work for 6 ± 4.7 years. Mean urinary mercury concentrations 1 year after cessation of work were 1.8 ± 0.9 µg/g creatinine. Twenty control subjects matched for age, gender, and education (18 males) were used for comparison. Neuropsychological assessment included attention, inhibitory control, verbal and visual memory, verbal fluency, manual dexterity, visual-spatial function, executive function, and semantic knowledge tests. The Beck Depression Inventory and the State and Trait Inventory were used to assess depression and anxiety symptoms, respectively. The raw score for the group exposed to mercury indicated slower information processing speed, inferior performance in psychomotor speed, verbal spontaneous recall memory, and manual dexterity of the dominant hand and non-dominant hand (P < 0.05). In addition, the patients showed increased depression and anxiety symptoms (P < 0.001). A statistically significant correlation (Pearson) was demonstrable between mean urinary mercury and anxiety trait (r = 0.75, P = 0.03). The neuropsychological performances of the former workers suggest that occupational exposure to elemental mercury has long-term effects on information processing and psychomotor function, with increased depression and anxiety also possibly reflecting the psychosocial context.

Color-space distortions following long-term occupational exposure to mercury vapor

Color vision was examined in subjects with long-term occupational exposure to mercury (Hg) vapor. The color vision impairment was assessed by employing a quantitative measure of distortion of individual and group perceptual color spaces. Hg subjects (n = 18; 42.1 +/- 6.5 years old; exposure time = 10.4 +/- 5.0 years; time away from the exposure source = 6.8 +/- 4.6 years) and controls (n = 18; 46.1 +/- 8.4 years old) were examined using two arrangement tests, D-15 and D-15d, in the traditional way, and also in a triadic procedure. From each subject`s `odd-one-out` choices, matrices of inter-cap subjective dissimilarities were derived and processed by non-metric multidimensional scaling (MDS). D-15d results differed significantly between the Hg-group and the control group (p < 0.05), with the impairment predominantly along the tritan axis. 2D perceptual color spaces, individual and group, were reconstructed, with the dimensions interpreted as the red-green (RG) and the blue-yellow (BY) systems. When color configurations from the Hg-group were compared to those of the controls, they presented more fluctuations along both chromatic dimensions, indicating a statistically significant difference along the BY axis. In conclusion, the present findings confirm that color vision impairments persist in subjects that have received long-term occupational exposure to Hg-vapor although, at the time of testing, they were presenting mean urinary concentration within the normal range for non-exposed individuals. Considering the advantages of the triadic procedure in clinical evaluation of acquired color vision deficiencies, further studies should attempt to verify and/or improve its efficacy.

Preliminary Findings on the Effects of Occupational Exposure to Mercury Vapor Below Safety Levels on Visual and Neuropsychological Functions

Objective: To evaluate whether there are visual and neurophysical decrements in workers with low exposure to Hg vapor. Methods: Visual fields, contrast sensitivity, color vision, and neuropsychological functions were measured in 10 workers (32.5 +/- 8.5 years) chronically exposed to Hg vapor (4.3 +/- 2.8 years; urinary Hg concentration 22.3 +/- 9.3 mu g/g creatinine). Results: For the worst eyes, we found altered visual field thresholds, lower contrast sensitivity, and color discrimination compared with controls (P < 0.05). There were no significant differences between Hg-exposed subjects and controls on. neuropsychological tests. Nevertheless, duration of exposure was statistically correlated to verbal memory and depression scores. Conclusions: Chronic exposure to Hg vapor at currently accepted safety levels was found to be associated with visual losses but not with neuropsychological dysfunctions in the sample of workers studied. (J Occup Environ Med. 2009,51:1403-1412)

Irreversible color vision losses in patients with chronic mercury vapor intoxication

This longitudinal study addresses the reversibility of color vision losses in subjects who had been occupationally exposed to mercury vapor. Color discrimination was assessed in 20 Hg-exposed patients (mean age = 42.4 +/- 6.5 years; 6 females and 14 males) with exposure to Hg vapor during 10.5 +/- 5.3 years and away from the work place (relative to 2002) for 6.8 +/- 4.2 years. During the Hg exposure or up to one year after ceasing it, mean urinary Hg concentration was 47 +/- 35.4 mu g/g creatinine. There was no information on Hg urinary concentration at the time of the first tests, in 2002 (Ventura et al., 2005), but at the time of the follow-up tests, in 2005, this value was 1.4 +/- 1.4 mu g/g creatinine for patients compared with 0.5 +/- 0.5 mu g/g creatinine for controls (different group from the one in Ventura et al. (2005)). Color vision was monocularly assessed using the Cambridge Colour Test (CCT). Hg-exposed patients had significantly worse color discrimination (p < 0.02) than controls, as evaluated by the size of MacAdam`s color discrimination ellipses and color discrimination thresholds along protan, deutan, and tritan confusion axes. There were no significant differences between the results of the study in Ventura et al. (2005) and in the present follow-up measurements, in 2005, except for worsening of the tritan thresholds in the best eye in 2005. Both chromatic systems, blue-yellow and red-green, were affected in the first evaluation (Ventura et al., 2005) and remained impaired in the follow-up testing, in 2005. These findings indicate that following a long-term occupational exposure to Hg vapor, even several years away from the source of intoxication, color vision impairment remains irreversible.

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. (C) 2007 Elsevier Inc. All rights reserved.

Electrophysiological evidence for impairment of contrast sensitivity in mercury vapor occupational intoxication

Contrast sensitivity (CS) was evaluated in 41 former workers from a lamp manufacturing plant who were on disability retirement due to exposure to mercury and 14 age-matched controls. The CS was measured monocularly using the sweep visual evoked potential (sVEP) paradigm at 6 spatial frequencies (0.2, 0.8, 2.0, 4.0, 15.0, and 30 cpd). Statistical difference (p < 0.05) was found between the controls and the patient right and left eyes for 2.0 and 4.0 cpd. According the results in those spatial frequencies the eyes were classified in best and worst. Statistical differences were found between the controls and the best eyes for 2.0 and 4.0 cpd and for 0.8, 2.0, and 4.0 cpd for their worst eyes. No correlation was found between CS results and the time of exposure (mean 8.9 yr +/- 4.1), time away from the mercury source (mean = 6.0 yr +/- 3.9), urinary mercury level at the time of work (mean = 40.6 mu g/g +/-36.3) or with the mercury level at the CS measurement time (mean = 1.6 mu g/g +/-1.1). We show the first evidence of a permanent impairment in CS measured objectively with the sVEP. Our data complement the previous psychophysical works reporting a diffuse impairment in the CS function showing a CS reduction in the low to middle spatial frequencies. In conclusion, non-reversible CS impairment was found in occupational exposure to mercury vapor. We suggest that CS measurement should be included in studies of the mercury effects of occupational exposure. (C) 2007 Elsevier Inc. All rights reserved.

UV-Ozone Generation from Modified High Intensity Discharge Mercury Vapor Lamps for Treatment of Indium Tin Oxide Films

In a homemade UV-Ozone generator, different ignition tubes extracted from HID mercury vapor lamps were investigated, namely: 80, 125, 250 and 400 watts. The performance of the generator in function of the type of the ignition lamp was monitored by the measurements of the ozone concentration and the temperature increment. The results have shown that the 400 W set up presented the highest ozone production, which was used in the treatment of indium tin oxide (ITO) films. Polymer light emitting diodes were assembled using ITO films, treated for 10, 20 and 30 min, as an anode. The overall results indicate improvement of the threshold voltage (reduction) and electroluminescence of these devices.

Apparatus and Method for Removing Mercury Vapor from a Gas Stream

A metallic filter effectively removes vapor from gas streams. The filter captures the mercury which then can be released and collected as a product. The metallic filter is a copper mesh sponge plated with a six micrometer thickness of gold. The filter removes up to 90% of mercury vapor from a mercury contaminated gas stream.

Reversible intermittent flow-injection determination of mercury in sediments and vinasses by cold vapor atomic absorption spectrometry

A reversible intermittent pow-injection procedure is proposed for the automated determination of mercury in sediments and vinasses by cold vapor atomic absorption spectrometry, CVAAS. Solutions of sample and stannous chloride are carried by two air streams and sequentially injected into the generator/separator chamber in a segmented asynchronous merging zone configuration. The intermittent flow in the forward direction carries the mercury vapor through the flow cell, and in the backward direction, if aspirates the the remaining solution from the vessel to waste. We investigated composition and concentration of reagents, pow rates, commutation times, reactor configuration, and conditions for mercury release. The accuracy was checked by mercury determination in a certified sediment and spiked vinasses and river waters. The system handles about 100 samples per hour (0.50-5.00 mu g L-1), consuming ca. 2.5 mL of sample and 50 mg of SnCl2 per determination; Good recoveries (92-103%) were obtained with spiked samples. Results are precise (RSD <3% for 2.5 mu g Hg L-1, n = 12) and in agreement with values for certified reference material at 95% confidence level. (C) 1999 John Wiley & Sons, Inc.

Análise e optimização dos consumos de utilidades (vapor e energia eléctrica) na Petibol – Embalagens de Plásticos, S.A.

Mestrado em Engenharia Química. Ramo optimização energética na indústria química.

Reator de UV-Ozônio com lâmpada a vapor de mercúrio a alta pressão modificada para tratamento superficial de óxidos transparentes condutivos utilizados em dispositivos poliméricos eletroluminescentes

An UV-Ozone reactor was developed with an ignition tube extracted into HID mercury lamp used to irradiation on zinc oxide (ZnO) and fluorinated tin oxide (FTO) films for PLEDs devices. Different exposures times were used. In contact angle measurements revealed better results for ZnO and FTO by 15 and 5 min, respectively. In Diffuse Reflectance Infra-red Fourier Transformed (DRIFT) spectroscopy allowed the observation of water, hydrocarbon and carbon dioxide adsorbed on the untreated TCO surfaces. After the UV-Ozone treatment the contaminants were significantly reduced or eliminated and the PLEDs devices decreased threshold voltages in comparison with respectively untreated TCOs.

Mercury toxicity in Amazon gold miners: Visual dysfunction assessed by retinal and cortical electrophysiology

Amazonian gold mining activity results in human exposure to mercury vapor. We evaluated the visual system of two Amazonian gold miners (29 and 37 years old) by recording the transient pattern electroretinogram (tPERG) and transient pattern visual evoked potential (tPVEP). We compared these results with those obtained from a regional group of control subjects. For both tPERG and tPVEP, checkerboards with 0.5 or 2 cycles per degree (cpd) of spatial frequency were presented in a 16 degrees squared area, 100% Michelson contrast, 50cd/m(2) mean luminance, and 1 Hz square-wave pattern-reversal presentation. Two averaged waveforms (n = 240 sweeps, Is each) were monocularly obtained for each subject in each condition. Both eyes were monocularly tested only in gold miners. Normative data were calculated using a final pooled waveforin with 480 sweeps. The first gold miner, LCS, had normal tPERG responses. The second one, RNP, showed low tPERG (P50 component) amplitudes at 0.5cpd for both eyes, outside the normative data, and absence of response at 2 cpd for his right eye. Delayed tPVEP responses (P 100 component) were found at 2 cpd for LCS but the implicit times were inside the normative data. Subject RNP also showed delayed tPVEP responses (all components), but only the implicit time obtained with his right eye was outside the normative data at 2cpd. We conclude that mercury exposure levels found in the Amazon gold miners is high enough to damage the visual system and can be assessed by non-invasive electrophysiological techniques. (C) 2007 Elsevier Inc. All rights reserved.

(Table 3, page 309) Mercury content of concretions from Grand Lake (GL) and Ship Harbour Lake (SH), Nova Scotia and Mosque Lake (ML), Ontario

Ferromanganese concretions from Grand Lake and Ship Harbour Lake in Nova Scotia and Mosque Lake in Ontario are most common in water 0.5 to 2 m deep. X-ray diffraction studies show the ferromanganese portions of the concretions to he amorphous. Petrographic and electron probe studies of the ferromanganese material reveal chemical banding of iron and manganese. Bulk chemical analyses indicate that the Fe:Mn ratios of concretions from different sites within a single lake are similar, whereas concretions from different lakes have characteristic Fe:Mn ratios. Trace element concs are different in different lakes and are generally several orders of magnitude less than those of oceanic nodules.

Mercury in Gas Operations - Occupational Health Risk Assessment

The project goal was to determine plant operations and maintenance worker’s level of exposure to mercury during routine and non-routine (i.e. turnarounds and inspections) maintenance events in eight gas processing plants. The project team prepared sampling and analysis plans designed to each plant’s process design and scheduled maintenance events. Occupational exposure sampling and monitoring efforts were focused on the measurement of mercury vapor concentration in worker breathing zone air during specific maintenance events including: pipe scrapping, process filter replacement, and process vessel inspection. Similar exposure groups were identified and worker breathing zone and ambient air samples were collected and analyzed for total mercury. Occupational exposure measurement techniques included portable field monitoring instruments, standard passive and active monitoring methods and an emerging passive absorption technology. Process sampling campaigns were focused on inlet gas streams, mercury removal unit outlets, treated gas, acid gas and sales gas. The results were used to identify process areas with increased potential for mercury exposure during maintenance events. Sampling methods used for the determination of total mercury in gas phase streams were based on the USEPA Methods 30B and EPA 1631 and EPA 1669. The results of four six-week long sampling campaigns have been evaluated and some conclusions and recommendations have been made. The author’s role in this project included the direction of all field phases of the project and the development and implementation of the sampling strategy. Additionally, the author participated in the development and implementation of the Quality Assurance Project Plan, Data Quality Objectives, and Similar Exposure Groups identification. All field generated data was reviewed by the author along with laboratory reports in order to generate conclusions and recommendations.