ABSTRACT
OBJECTIVES: To validate the ecological modification of the Papanicolaou stain (Eco-Pap) for the diagnosis of cervical cancer. STUDY DESIGN: A prospective study was performed at the Mother and Child "San Bartolomé" Hospital, Lima, Peru. Reagent handling strategies were divided into three phases: we used (1) Harris progressive hematoxylin (for nuclear staining), (2) a polychromatic solution (a mix of EA-36/Orange G-6 to suppress the use of several alcohol baths), and (3) direct mounting (with Entellan® solution). The cellular details were analyzed by the staining quality index, an external quality control, and the Bethesda System 2014. RESULTS: We evaluated 72,901 cervical smears stained with the Eco-Pap. The validation of the Eco-Pap against the conventional Pap stain was optimal (κ = 0.89; 95% CI: 0.87-0.92), showing a sensibility and specificity of 88.3% (95% CI: 85.1-90.0) and 98.7% (95% CI: 98-99.2), respectively. The Eco-Pap dramatically reduced the environmental pollution caused by 72 L of xylene, hydrochloric acid, and ammonia (6 L each) and mercury oxide. CONCLUSION: The Eco-Pap is an innovative and efficient staining method reducing the use of toxic reagents with carcinogenic potential during cervical cancer screening by exfoliative cytology.
Subject(s)
Environmental Pollutants/adverse effects , Environmental Pollution/prevention & control , Medical Waste Disposal , Papanicolaou Test/methods , Staining and Labeling/methods , Uterine Cervical Neoplasms/pathology , Vaginal Smears , Ammonia/adverse effects , Azo Compounds/chemistry , Coloring Agents/chemistry , Cross-Sectional Studies , Environmental Pollution/adverse effects , Female , Hematoxylin/chemistry , Humans , Hydrochloric Acid/adverse effects , Mercury Compounds/adverse effects , Oxides/adverse effects , Papanicolaou Test/adverse effects , Peru , Predictive Value of Tests , Prospective Studies , Reproducibility of Results , Xylenes/adverse effectsABSTRACT
Mercury and its compounds are classified into three main groups: metallic mercury (Hg0), inorganic mercury (Hg2+), and organic mercury (methyl mercury: CH3Hg+, etc.). Metallic mercury is the only metal that is liquid at ambient temperature and normal pressure, which readily forms an amalgam with other metals. Therefore, mercury has long been used for refining various metals, and mercury amalgam has been used for dental treatment. Mercury has also been used in measuring instruments such as thermometers, barometers and blood pressure monitors, as well as electric appliances such as lighting equipment and dry batteries. Large amounts of metallic mercury are still used in other countries as a catalyst in the production of caustic soda by electrolysis. In addition, mercury compounds have been used in various chemicals such as mercurochrome, agricultural chemicals, and mildew-proofing agents. However, the use of mercury has also caused health problems for people. Minamata disease in Japan is a typical example. Also, since mercury is highly volatile, it is discharged as a product of industrial activities or derived from volcanoes, and it has been concluded on the basis of the findings of the United Nations Environment Program (UNEP) that it is circulating globally. Therefore, with the aim of establishing an internationally legally binding treaty for the regulation of mercury use to reduce risk, an intergovernmental negotiating committee was established in 2009. Japan actively contributed to this negotiation owing to its experience with Minamata disease, which led to the Convention on the regulation of mercury use being discharged as the "Minamata Convention on Mercury" and the treaty came into force on August 16, 2017. In this review, we introduce 1) the Global Mercury Assessment by UNEP; 2) mercury kinetics, exposure assessment and toxicity of different chemical forms; 3) large-scale epidemics of methylmercury poisoning; 4) methylmercury exposure assessment and health survey in whale-eating populations; 5) elemental mercury exposure assessment and health survey of mercury mine workers in China.
Subject(s)
Environmental Exposure/adverse effects , Environmental Pollutants/adverse effects , Environmental Pollutants/toxicity , Mercury Compounds/adverse effects , Mercury Compounds/toxicity , Occupational Exposure/adverse effects , Risk Assessment , Animals , Fishes/metabolism , Global Health , Humans , Mercury Compounds/metabolism , Mercury Compounds/poisoning , Mercury Poisoning, Nervous System/etiology , Mercury Poisoning, Nervous System/immunology , Mercury Poisoning, Nervous System/metabolism , Methylmercury Compounds/adverse effects , Methylmercury Compounds/metabolism , Methylmercury Compounds/poisoning , Methylmercury Compounds/toxicityABSTRACT
Zuotai, a famous Tibetan medicinal mixture containing ß-HgS, has been used to combine with herbal remedies for treating diseases for more than 1 300 years. The target organ for inorganic mercury toxicity is generally considered to be the kidney. Therefore, it is crucial to reveal the chemical speciation, spatial distribution and potential nephrotoxicity of mercury from Zuotai in kidney. To date, this remains poorly understood. We used X-ray absorption spectroscopy (XAS) and micro X-ray fluorescence (µ-XRF) imaging based on synchrotron radiation to study mercury chemical forms and mercury special distribution in kidney after mice were treated orally with Zuotai, ß-HgS or HgCl2. Meanwhile, the histopathology of kidney was observed. Mice exposed with Zuotai showed kidney with significant proportion of mercury ions bound to sulfydryl biomolecules (e.g. Cys-S-Hg-S-Cys) plus some of unknown species, but without methylmercury cysteine, which is the same as ß-HgS and HgCl2. The mercury is mainly deposited in renal cortex in mouse treated with Zuotai, ß-HgS or HgCl2, but with a low level of mercury in medulla. The total mercury in kidney of mice treated with HgCl2 was much higher than that of ß-HgS, and the later was higher than that of Zuotai. And, HgCl2 cause severe impairments in mouse kidney, but that was not observed in the Zuotai and ß-HgS groups. Meanwhile, the bio-metals (Ca, Zn, Fe and Cu) micro-distributions in kidney were also revealed. These findings elucidated the chemical nature, spatial distribution and toxicity difference of mercury from Zuotai, ß-HgS and HgCl2 in mouse kidney, and provide new insights into the appropriate methods for biological monitoring.
Subject(s)
Kidney/drug effects , Mercuric Chloride/adverse effects , Mercury Compounds/adverse effects , Animals , Mercuric Chloride/analysis , Mercury Compounds/analysis , MiceSubject(s)
Coloring Agents/adverse effects , Granuloma Annulare/chemically induced , Necrobiotic Disorders/chemically induced , Tattooing/adverse effects , Arm , Dermis/pathology , Female , Granuloma Annulare/pathology , Humans , Inflammation , Mercury Compounds/adverse effects , Necrobiotic Disorders/pathology , Skin Ulcer/etiology , Young AdultSubject(s)
Coloring Agents/adverse effects , Drug Eruptions/etiology , Ink , Lichenoid Eruptions/etiology , Tattooing/adverse effects , Anti-Inflammatory Agents/therapeutic use , Clobetasol/therapeutic use , Coloring Agents/chemistry , Drug Eruptions/diagnosis , Drug Eruptions/drug therapy , Female , Foot , Humans , Lichenoid Eruptions/diagnosis , Lichenoid Eruptions/drug therapy , Mercury Compounds/adverse effects , Metals, Heavy/adverse effects , Pruritus/etiology , Young AdultABSTRACT
Mercury pollution and its impacts on human health is of global concern. The authors of this paper were members of the Plenary Panel on Human Health in the 12th International Conference on Mercury as a Global Pollutant held in Korea in June 2015. The Panel was asked by the conference organizers to address two questions: what is the current understanding of the impacts of mercury exposure on human health and what information is needed to evaluate the effectiveness of the Minamata Convention in lowering exposure and preventing adverse effects. The authors conducted a critical review of the literature published since January 2012 and discussed the current state-of-knowledge in the following areas: environmental exposure and/or risk assessment; kinetics and biomonitoring; effects on children development; effects on adult general populations; effects on artisanal and small-scale gold miners (ASGM); effects on dental workers; risk of ethylmercury in thimerosal-containing vaccines; interactions with nutrients; genetic determinants and; risk communication and management. Knowledge gaps in each area were identified and recommendations for future research were made. The Panel concluded that more knowledge synthesis efforts are needed to translate the research results into management tools for health professionals and policy makers.
Subject(s)
Environmental Exposure , Health Status , Mercury Compounds/adverse effects , Mercury/adverse effects , Humans , Mercury/toxicity , Risk AssessmentABSTRACT
INTRODUCTION: There is evidence that high levels of mercury exposure to the pregnant woman can result in damage to the brain of the developing fetus. However there is uncertainty as to whether lower levels of the metal have adverse effects on the development of the infant and whether components of fish consumption and/or the selenium status of the woman is protective. METHODS: In this study we analysed data from the Avon Longitudinal Study of Parents and Children (ALSPAC) (n=2875-3264) to determine whether levels of total blood mercury of pregnant women collected in the first half of pregnancy are associated with the development of the offspring at ages 6, 18, 30 and 42 months. The developmental measures used maternal self-reported scales for individual types of development (fine and gross motor, social and communication skills) and total scores. Multiple and logistic regression analyses treated the outcomes both as continuous and as suboptimal (the lowest 15th centile). The statistical analyses first examined the association of prenatal mercury exposure with these developmental endpoints and then adjusted each for a number of social and maternal lifestyle factors; finally this model was adjusted for the blood selenium level. RESULTS: Total maternal prenatal blood mercury and selenium ranged from 0.17 to 12.76 and 17.0 to 324µg/L respectively. We found no evidence to suggest that prenatal levels of maternal blood mercury were associated with adverse development of the child, even when the mother had consumed no fish during pregnancy. In general, the higher the mercury level the more advanced the development of the child within the range of exposure studied. For example, the fully adjusted effect sizes for total development at 6 and 42 months were +0.51 [95%CI +0.05, +1.00] and +0.43 [95%CI +0.08, +0.78] points per SD of mercury. For the risk of suboptimal development the ORs at these ages were 0.90 [95%CI 0.80, 1.02] and 0.88 [95%CI 0.77, 1.02]. In regard to the associations between blood mercury and child development there were no differences between the mothers who ate fish and those who did not, thus implying that the benefits were not solely due to the beneficial nutrients in fish. CONCLUSIONS: We found no evidence of adverse associations between maternal prenatal blood mercury and child development between 6 and 42 months of age. The significant associations that were present were all in the beneficial direction.
Subject(s)
Developmental Disabilities/etiology , Mercury Compounds/adverse effects , Prenatal Exposure Delayed Effects/physiopathology , Age Factors , Child, Preschool , Developmental Disabilities/blood , Developmental Disabilities/epidemiology , Female , Food Contamination , Humans , Infant , Longitudinal Studies , Male , Maternal Exposure/adverse effects , Mercury Compounds/blood , Outcome Assessment, Health Care , Pregnancy , Prenatal Exposure Delayed Effects/blood , Prenatal Exposure Delayed Effects/epidemiology , Retrospective Studies , Selenium/blood , Surveys and QuestionnairesABSTRACT
AIM: Mercury, an environmental contaminant, is a risk factor for health in whole living organisms. In this study, we investigated whether mercury vapor (HgO) inhalation has an effect on rat ovary. METHODS: Twelve Wistar albino rats were divided equally into experimental (Hg) and control groups (n = 6). Animals in the Hg group were exposed to HgO for 45 days at a dose 1 mg/m(3)/day, after which, histological and stereological assessment were carried out. RESULTS: Ovaries exposed to HgO had histo-morphometric alterations. HgO inhalation resulted in reduction of the total number of primordial, primary and Graaf follicles. Also, mean volume of ovary, medulla and cortex, corpus luteum (c. luteum) and Graaf follicles was decreased in the Hg group. Moreover, there was a significant increase in total volume of the atretic follicles. On light microscopy, thickening of tunica albuginea, increase of fibrils within the connective tissue, congestion of the capillaries and venous vessels, thinned walls and fibrin deposition in some large blood vessels, and edema were seen. Also, irregular follicle and oocyte borders, and hydropic degeneration in follicular granulosa cells were detected. CONCLUSION: Structural alterations could be attributed to the toxic influence of HgO on rat ovary. The use of Hg should therefore be more controlled to minimize its toxic effect.
Subject(s)
Mercury/administration & dosage , Mercury/adverse effects , Ovary/drug effects , Administration, Inhalation , Animals , Corpus Luteum/drug effects , Corpus Luteum/pathology , Female , Mercury Compounds/administration & dosage , Mercury Compounds/adverse effects , Ovarian Follicle/drug effects , Ovarian Follicle/pathology , Ovary/pathology , Oxides/administration & dosage , Oxides/adverse effects , Rats , Rats, WistarABSTRACT
AIMS: The aim of this study is to assess the neuropsychological manifestations of mercury exposure in dentists. METHODS: A cross-sectional study was carried out including 64 dentists matched to a control group according to age and gender. This study protocol included a neurological evaluation, a questionnaire assessing the study groups' general characteristics and personal factors that may affect mercury urinary excretion in both groups. EUROQUEST questionnaire and Hospital Anxiety and Depression scale (HADS) were used to evaluate the neuropsychological symptoms reported during the last 12 months. In both groups, mercury impregnation was assessed by monitoring urinary mercury. RESULTS: In the exposed group, scores of neurological symptoms, memory disturbances and anxiety were found to be significantly higher than those in controls (p < 0.01). Mean scores of HAD Depression's scale were higher in the exposed group than in controls. Most of the neurotoxic manifestations were correlated to the levels of urinary mercury excretion in the exposed group. Mean levels of urinary mercury were significantly higher in the dentists group than in controls, with respective values of 21.1 ± 19.6 µg/g of creatinine and 0.05 ± 0.9 µg/g of creatinine. In nine dentists having urinary mercury levels higher than 35 µg/g of creatinine, neurological examination showed a bilateral and symmetric intentional tremor in both upper limbs. In the exposed group, the neuropsychological manifestations and levels of urinary mercury were found to be significantly correlated. CONCLUSION: Increased levels of urinary mercury observed in dentists suggest that exposure to mercury vapour emissions adversely affects dental professionals, therefore prevention measures should be strengthened, with a special medical supervision program of dentists exposed to mercury vapours should be implemented. We have also outlined some relevant patents in this article.
Subject(s)
Dental Restoration, Permanent/adverse effects , Dental Restoration, Temporary/adverse effects , Dentists , Mercury Compounds/adverse effects , Mercury Poisoning, Nervous System/etiology , Occupational Diseases/chemically induced , Occupational Exposure/adverse effects , Occupational Health , Adult , Anxiety/chemically induced , Anxiety/psychology , Biomarkers/urine , Cross-Sectional Studies , Female , Humans , Male , Memory/drug effects , Memory Disorders/chemically induced , Memory Disorders/psychology , Mercury Compounds/urine , Mercury Poisoning, Nervous System/diagnosis , Mercury Poisoning, Nervous System/prevention & control , Mercury Poisoning, Nervous System/psychology , Middle Aged , Neurologic Examination , Occupational Diseases/diagnosis , Occupational Diseases/prevention & control , Occupational Diseases/psychology , Occupational Exposure/prevention & control , Risk Assessment , Risk Factors , Surveys and Questionnaires , Tremor/chemically induced , Tunisia , Urinalysis , VolatilizationABSTRACT
The purpose of this study was to investigate whether cinnabar causes renal inflammation and fibrosis in rats. Rats were dosed orally with cinnabar (1 g/kg/day) for 8 weeks or 12 weeks. The control rats were treated with solvent (5% carboxymethylcellulose solution) over the same time periods, respectively. Renal mercury (RHg), urinary mercury (UHg), serum creatinine (SCr), urine kidney injury molecule 1 (KIM-1), renal pathology, and renal mediators were examined. At both 8 weeks and 12 weeks, RHg, UHg, and urine KIM-1 were significantly higher in the cinnabar group than in the control group, although SCr was unchanged. Kidney lesions in the cinnabar-treated rats occurred mainly in the tubules and interstitium, including vacuolization, protein casts, infiltration of inflammatory cells, and slight increase in interstitial collagen. In addition, mild mesangial proliferation was observed in glomeruli. Moreover, the expression of inflammatory and fibrogenic mediators was upregulated in the cinnabar group. In conclusion, cinnabar may cause kidney damage due to the accumulation of mercury, and renal inflammation and slight fibrogenesis may occur in rats. In the clinic, the potential risk of renal injury due to the prolonged consumption of cinnabar should be considered even though the agent is relatively nontoxic.
Subject(s)
Kidney/metabolism , Kidney/pathology , Mercury Compounds/adverse effects , Mercury Compounds/pharmacokinetics , Nephritis/chemically induced , Nephritis/metabolism , Administration, Oral , Animals , Fibrosis/chemically induced , Fibrosis/metabolism , Fibrosis/pathology , Kidney/drug effects , Mercury Compounds/administration & dosage , Metabolic Clearance Rate , Nephritis/pathology , Rats , Rats, Sprague-DawleyABSTRACT
A 28-year-old female suffered from nephrotic syndrome after a long-term use of mercury-containing, skin-lightening cream. The blood and urinary mercury content of this patient increased with use. Renal biopsy showed minimal change disease. Her symptoms were relieved 6 months after discontinuing use of the cream and receiving sodium dimercaptosulfonate and glucocorticosteroid treatments. Proteinuria disappeared, and blood and urinary mercury levels returned to normal. Previous reports of nephrotic syndrome caused by mercury-containing, skin-lightening creams have mostly been identified as be.ing due to membranous nephropathy. Minimal change disease has been reported in a few case reports published in the English language. Here we report a case of nephrotic syndrome with minimal change disease following exposure to a mercury-containing, skin-lightening cream. We also reviewed relevant published reports to summarize clinical features and treatments and to explore the possible mechanisms involved.
Subject(s)
Mercury Compounds/adverse effects , Nephrosis, Lipoid/chemically induced , Nephrotic Syndrome/chemically induced , Skin Lightening Preparations/adverse effects , Adult , Female , Glucocorticoids/therapeutic use , Humans , Mercury Compounds/administration & dosage , Nephrosis, Lipoid/drug therapy , Nephrosis, Lipoid/physiopathology , Nephrotic Syndrome/drug therapy , Nephrotic Syndrome/physiopathology , Proteinuria/chemically induced , Skin Lightening Preparations/administration & dosage , Time Factors , Unithiol/therapeutic useABSTRACT
The aim of the study was to determine the prognosis and to evaluate the regression of lichenoid contact reactions (LCR) and oral lichen planus (OLP) after replacement of dental restorative materials suspected as causing the lesions. Forty-four referred patients with oral lesions participated in a follow-up study that was initiated an average of 6 years after the first examination at the Department of Odontology, i.e. the baseline examination. The patients underwent odontological clinical examination and answered a questionnaire with questions regarding dental health, medical and psychological health, and treatments undertaken from baseline to follow-up. After exchange of dental materials, regression of oral lesions was significantly higher among patients with LCR than with OLP. As no cases with OLP regressed after an exchange of materials, a proper diagnosis has to be made to avoid unnecessary exchanges of intact restorations on patients with OLP.
Subject(s)
Dental Amalgam/adverse effects , Lichen Planus, Oral/pathology , Lichenoid Eruptions/pathology , Mouth Mucosa/pathology , Adult , Aged , Analysis of Variance , Female , Follow-Up Studies , Gold Alloys/adverse effects , Humans , Lichen Planus, Oral/etiology , Lichen Planus, Oral/immunology , Lichenoid Eruptions/immunology , Male , Mercury Compounds/adverse effects , Metal Ceramic Alloys/adverse effects , Middle Aged , Mouth Mucosa/immunology , Nickel/adverse effects , Remission Induction , Surveys and Questionnaires , Time Factors , Treatment OutcomeSubject(s)
Lymphoma, Large-Cell, Anaplastic/chemically induced , Lymphomatoid Papulosis/chemically induced , Skin Neoplasms/chemically induced , Tattooing/adverse effects , Coloring Agents/adverse effects , Drug Eruptions/etiology , Female , Humans , Mercury Compounds/adverse effects , Pseudolymphoma/diagnosis , Skin Diseases/diagnosis , Young AdultABSTRACT
More than a decade in the making, a new, legally binding treaty on mercury will be adopted by governments in the fall of 2013. The treaty's objective is to protect human health and the environment from anthropogenic mercury emissions through a range of provisions - including an article devoted to reducing exposure to mercury. Global emissions have increased since 2005, with the environmental health burden increasingly shifting to developing countries. Time is of the essence to reduce pollution because (i) exposure risk to mercury is much greater than previously thought and (ii) mercury already in the environment can be re-emitted via processes in the natural cycle, resulting in a longer lag time before pollution reduction can have a demonstrable effect on the food chain. Health professionals can assist in reducing exposure, choosing mercury-free products and urging governments to ratify the treaty as quickly as possible so that it can take effect.
Subject(s)
Environmental Exposure/prevention & control , International Cooperation/legislation & jurisprudence , Mercury Poisoning/prevention & control , Environmental Exposure/legislation & jurisprudence , Health Promotion , Humans , Mercury Compounds/adverse effects , Public Health Administration , Risk FactorsSubject(s)
Mercury Compounds/adverse effects , Mercury Poisoning/complications , Mercury Poisoning/diagnosis , Mercury/blood , Mercury/urine , Plant Preparations/adverse effects , Adult , Antidotes/therapeutic use , Chelating Agents/therapeutic use , China , Delirium/chemically induced , Diagnosis, Differential , Fluid Therapy , Gait , Humans , Male , Mass Spectrometry , Mercury Compounds/administration & dosage , Mercury Poisoning/blood , Mercury Poisoning/psychology , Mercury Poisoning/therapy , Mercury Poisoning/urine , Muscle Weakness/chemically induced , Narcolepsy/chemically induced , Pain/chemically induced , Peripheral Nervous System Diseases/chemically induced , Plant Preparations/administration & dosage , Posture , Psoriasis/drug therapy , Sleep Wake Disorders/chemically induced , Treatment Outcome , Tremor/chemically induced , Unithiol/therapeutic useABSTRACT
The purpose of this review is to examine the evidence for a relationship between mercury (Hg) exposure from dental amalgams and certain idiopathic chronic illnesses--chronic fatigue syndrome (CFS), fibromyalgia (FM), depression, anxiety, and suicide. Dental amalgam is a commonly used dental restorative material that contains approximately 50% elemental mercury (Hg0) by weight and releases Hg0 vapor. Studies have shown that chronic Hg exposure from various sources including dental amalgams is associated with numerous health complaints, including fatigue, anxiety, and depression--and these are among the main symptoms that are associated with CFS and FM. In addition, several studies have shown that the removal of amalgams is associated with improvement in these symptoms. Although the issue of amalgam safety is still under debate, the preponderance of evidence suggests that Hg exposure from dental amalgams may cause or contribute to many chronic conditions. Thus, consideration of Hg toxicity may be central to the effective clinical investigation of many chronic illnesses, particularly those involving fatigue and depression.
Subject(s)
Anxiety/etiology , Dental Amalgam/adverse effects , Depression/etiology , Fatigue/etiology , Mercury Compounds/adverse effects , Suicide , Chronic Disease , Evidence-Based Practice , Fibromyalgia/etiology , HumansABSTRACT
Recent research has highlighted the transfer of contaminants from aquatic to terrestrial ecosystems via predation of aquatic emergent insects by riparian consumers. The influence of adjacent land use and land cover (LULC) on aquatic-to-terrestrial contaminant transfer, however, has received limited attention. From 2010 to 2012, at 11 river reaches in the Scioto River basin (OH, USA), we investigated the relationships between LULC and selenium (Se) and mercury (Hg) concentrations in four species of riparian swallows. Hg concentrations in swallows were significantly higher at rural reaches than at urban reaches (t=-3.58, P<0.001, df=30), whereas Se concentrations were positively associated with adjacent land cover characterized by mature tree cover (R(2)=0.49, P=0.006). To an extent, these relationships appear to be mediated by swallow reliance on aquatic emergent insects. For example, tree swallows (Tachycineta bicolor) at urban reaches exhibited a higher proportion of aquatic prey in their diet, fed at a higher trophic level, and exhibited elevated Se levels. We also found that both Se and Hg concentrations in adult swallows were significantly higher than those observed in nestlings at both urban and rural reaches (Se: t=-2.83, P=0.033, df=3; Hg: t=-3.22, P=0.024, df=3). Collectively, our results indicate that riparian swallows integrate contaminant exposure in linked aquatic-terrestrial systems and that LULC may strongly regulate aquatic contaminant flux to terrestrial consumers.
Subject(s)
Mercury Compounds/blood , Rivers , Selenium Compounds/blood , Soil Pollutants/analysis , Swallows/blood , Water Pollutants, Chemical/analysis , Age Factors , Animals , Ecosystem , Environmental Monitoring , Insecta , Mercury Compounds/adverse effects , Mercury Compounds/analysis , Ohio , Selenium Compounds/adverse effects , Selenium Compounds/analysis , Soil Pollutants/adverse effects , Water Pollutants, Chemical/adverse effectsABSTRACT
Methylmercury (MeHg) is present in the environment because of natural and anthropogenic causes. MeHg can reach the central nervous system (CNS) and cause neurological damage in humans and animals. Electric organ discharges (EODs) in the weak electric fish Gymnotus sylvius are produced by the electric organ and modulated by the CNS. These discharges are used for electrolocation and communication. The purpose of the present study was to investigate the effects of dietary MeHg exposure on EOD rate in G. sylvius. An oscilloscope was used to record the EOD rate. Two treatments were investigated: chronic MeHg administration (4 µg/kg MeHg every 2 days, with a total of nine dietary exposures to MeHg) and acute MeHg administration (a single dose of 20 µg/kg MeHg). The control data for both treatments were collected every 2 days for 18 days, with a total of nine sessions (day 1 until day 18). Data of fish exposed to MeHg were collected every 2 days, totaling nine sessions (day 19 until day 36). Chronic treatment significantly increased the EOD rate in G. sylvius (p < .05), especially with the final treatment (day 32 until day 36). Acute treatment resulted in an initial increase in the EOD rate, which was maintained midway through the experiment (day 26 until day 30; p < .05). The present study provides the first insights into the effects of MeHg on EODs in weak electric fish. The EOD rate is a novel response of the fish to MeHg administration.