Mercury in Environmental and Biological Samples From a Gold Mining Area in the Amazon Region of Brazil

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Mercury in environmental and biologicalsamples from a gold mining area in theAmazon region of Brazil

ARTICLE in SCIENCE OFTHE TOTAL ENVIRONMENT · JUNE 1995

Impact Factor: 4.1 · DOI: 10.1016/0048-9697(95)04533-7 · Source: PubMed

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The Science of the Total Environment 168 (1995) 63-69

Mercury in environmental and biological samples from agold mining area in the Amazon region of Brazil

Dulcideia Palheta”, Andrew Taylor* b

a Trace Elem ents Laboratory, Robens Inst itute of Health and Safeiy, Universiry of Surrey, Guildford, Surrey GU.2 5XH, UK

bDepartmertt of Clinica l Biochemtim, St. Luke’s Hospital, Guildford, Surrey GUI 3NT UK

Received 2 September 1994; accepted 1 November 1994

Abstract

A massive ncrease n gold mining in the Amazon region of Brazil has ed to an enormous discharge of metallicmercury into the aquatic ecosystem. o investigate he dispersion otal and inorganic mercury concentrations weremeasured n water fish and animal tissues and in blood urine and hair from members of the local populations.

Mercury concentrations n river water sediments nd fish were high compared with those of non-contaminated areas.Cattle and pigs kept in the area and with access o the contaminated ivers had concentrations of mercury of 0.1-1.28pg/g and 11.7-15.7 pg/l in hair and blood respectively. These results are approximately twice those measured nspecimens rom control animals. Mean mercury concentrations n blood urine and hair of residents were increasedat 11.4 pg/l 22.8 pg/l and 4.3 pg/g respectively and the urine mercury of workers rom the gold mining sites wereup to 155 pg/l. The results demonstrate widespread ontamination of the environment by mercury with transfer ofthe metal to fish and animals sed or food and nto the inhabitants of the region. Further investigations or possibleadverse health effects need to be undertaken.

Keywords: Mercury; Gold mining; Amazon region; Blood; Hair; Urine

1. Introduction

Methylmercury is highly toxic to the centralnervous system and to the developing fetus [l]. It

*Corresponding author, Trace Elements Laboratory,Robens Institute of Health and Safe ty, University of Surrey,Guildford, Surrey GU2 5XH, UK.

has a long biological half-life and accumulatesthrough the food chain as was demonstrated inthe Minamata Bay incident where waste mercurydischarged into sea water was methylated andconcentrated into fish 5000-50 OOO-fold [2,3]. In-dividuals who ate the fish had symptoms ofdysarthria, ataxia and tunnel vision and therewere increased rates of miscarriage and fetal mal-formations among pregnant women. Toxicity

0048-9697/95/ 09.50 0 1995 Elsevier Science BV. All rights reserved.SSD I 0048-9697 95)04533-S


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64 D. Palheta, A . Taylor / The Scienc e of the Total Environment I68 1995) 63-69

caused by exposure to elemental mercury withdamage to the peripheral and central nervous

systems, the kidney and the fetus, has long beenrecognised [4,5].

In the last 10 years there has been a largeincrease in gold mining activity in the Amazonregion of Brazil [6,7]. Extraction of alluvial goldrequires the use of metallic mercury to form anamalgam of gold and mercury, and amounts in

excess of 100 tonnes/year are employed in Brazil.The amalgam is subsequently heated with release

of mercury vapour into the air. There is aIsodischarge of enormous amounts of mercury intothe Amazonian aquatic ecosystem with an imme-diate risk to the environment and to fish. Domes-tic and ‘farm’ animals who drink river water arealso exposed to increased amounts of mercury.Humans in these areas will be exposed to the

ATLANTIC OCEAN

Fig. 1. Diagramatic plan of the Gurupi gold field, Para, Brazil with water mercury concentrations represented by the size of theoatterned blocks


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D. Palheta, A. Taylor / The Science of the Total Enuironment 168 1995) 63-69 65

Table 1Samples collected for measurement of mercury

Source Specimen n Specimen n Specimen n

Water River 8 Tap 1Fish 7 diferent 38

speciesPig BloodSheep BloodCattle BloodHuman Blood

13 Hair 156 Hair 6

10 Hair 1023 Hair 35 Urine 25

metal in an occupational setting and/or via con-sumption of locally produced fish and meat. To

determine the actual dispersion of mercury andpossible health risks associated with gold extrac-tion, one area has been investigated with themeasurement of total and inorganic mercury inwater, fish and animal tissues, and in blood, urineand hair from members of the local populations.

2. Materials and methods

2.1. Collection of specimensSpecimens were collected at sites within the

Gurupi gold field in the northeast of the Brazilianstate of Para (Fig. 1). The village of Cachoeirawas selected as a base since it is an importantmarket and gold trading centre within the area.

Water. Samples of river water from sites along

Table 2Measurement of total mercury in blood, tissues and urine

the Gurupi, Piria and Macaco Rivers, and drinkingwater from the village of Cachoeira were col-

lected into containers with 0.2 ml KBrO, (0.1M)-KBr (1% m/v) and 0.2 ml HCl per 20 mlwater. Specimens were kept at 4°C until analysis.

Fish. Species regularly used as food were caughtin the rivers or bought from markets, their localnames were Piaba, Tucunare, Cachorrinho dePadre, Acara, Traira, Pacu and Mandii. Thespecimens were later identified by the NaturalHistory Museum, London as Characidae, Cichlusp. Cemicichla sp. Geophagus sp. Hophias mal-abtzricus c.f. Myleus sp. and Pimelodus sp. respec-

tively. Portions of edible tissues were removed foranalysis and stored at -20°C.Domestic animals. Specimens of hair and blood

were collected from pigs, sheep and cattle whichgrazed alongside and drank water from the Gu-rupi and Piria Rivers. A further series of speci-mens were obtained from animals at the ParaAgricultural College, not within the Gurupi area.

Human specimens. Blood, urine and hair wereobtained from villagers who live alongside theGurupi River, from residents of Cachoeira and

from ‘garimpeiros’ - the men who work at thegold fields. All blood, urine and hair specimenswere kept at 4°C until analysis.

The numbers of specimens collected for analy-sis are given in Table 1.

Hg added( /-G/l)

Hg found( /G/l)

BloodEndogenousInorganic mercuryMethylmercury

UrineEndogenousInorganic mercuryMethylmercury

Tissue homogenateEndogenousInorganic mercuryMethylmercury

- 5.2(+ 100) 105.8(+100) 116.8

- 3.7(+50) 51.6(+50) 45.5

- 11.2(+ 100) 104.9(+ 100) 103.2

102110

9691

- 7.294.9 11.494.6 11.0

Reproducibility(CV%‘o)

5.43.05.6

13.03.17.1

Accuracy and precision (number of replicates = 10).


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Table 3

D. Palheta, A. Taylor / The Scienc e of the Total Environment 168 1995) 63-69

Speciation of inorganic and organic mercury in urine

Hg added Hg found( /-G/l) ( cLg/l)

Recovery(%o)

Reproducibility(CV%o)

Endogenous - 2.8 - 9.5Inorganic mercury (+50) 54.0 102.5 3.3Methylmercury (+50) 4.2 2.5 4.7

Measurement of inorganic mercury. Accuracy and precision (number of replicates = 10)

2.2. Determination of mercuryTissue samples were homogenised for analysis

[8], hair was dissolved in 40% m/v NaOH [9] andblood wa s examined without pre-treatment [lo].

Concentrations of mercury were measured bycold-vapour atomic absorption spectrometry. To-tal mercury was measured using a stannous chlo-ride-cadmium chloride solution as the reductant.When a stannous chloride solution was used, onlythe inorganic mercury was determined [9].

Urine and water samples were digested at roomtemperature with KIMnO,-H,SO,, for the mea-surement of total mercury using stannous chlo-ride as the reductant. A second analysis, withoutdigestion, yielded the inorganic mercury concen-

trations [ 111.These procedures were evaluated using speci-mens spiked with mercuric chloride or meth-ylmercury. Recoveries of added mercury, and pre-cision were determined for all sample types.

3. Results

3.1. Accuracy and precision of the analyticalprocedures

The results for the recovery and reproducibility

Table 4Total and organic mercury concentrations in fish---Species No. of

samples

-

experiments are shown in Table 2 and demon-strate that the procedure measured mercury ac-curately and with good precision. The protocol todifferentiate between inorganic and organic mer-

cury species was also demonstrated to be effective(Table 3).

3.2. Mercury concentrations in water and biologicalsamples

Water mercury concentrations are shown inFig. 1. River water collected around the goldmining areas contained up to 800 rig/l mercurycompared with < 200 rig/l in the drinking waterand in river water upstream from the miningoperations. The highest concentrations were in a

lake which drained the mining area and in theRiver Gurupi close to the areas where the miningactivity was at its most intense. Concentrationsfell as tributaries and other sources caused theriver to increase greatly in size, with an effectivedilution of the mercury.

Total mercury concentrations in the fish speci-mens are given in Table 4. Higher levels occuredin carnivorous compared with plant eating species.The proportion of organic mercury in the samplesvaried from 87 to 100%.

Total mercury( /G/g)

Organicmercury (%)

Characidae 4 0.19 87Cichla sp. 3 0.11 91Crenicichla sp. 8 0.21 94Geophagus sp. 2 0.03 90Hoplias malabaricus 13 0.61 95

cf Myleus sp 2 0.04 100Pimelodus biochii 6 0.18 98


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D. Palheta, A. Taylor / The Scienc eof he Tota l Environment 168 1995) 63-69 67

Exposed animals Control animals

NS

Pigs Cattle Sheep

Fig. 2. Concentrations of mercury (@g/l) in blood samplesfrom pigs, cattle and sheep raised in the Gurupi gold field(exposed) and the Para Agricultural College (control). Signifi-cance between results from the two groups: *,P < 0.001; NS,not significant.

Total mercury levels in blood and hair from

domestic ‘farm’ animals are shown in Figs. 2 and3. Higher concentrations are evident in specimensfrom pigs compared with cattle and sheep, but forall animals the levels were higher than in similarspecies living in the agricultural college where

2.0

1 o

Control animals

Fig. 3. Concentrations of mercury (pg/g) in hair samplesfrom pigs, cattle and sheep raised in the Gurupi gold field(exposed) and the Para Agricultural College (control). NS, nosignificant difference between results from the two groups.

there was no exposure to mercury. These differ-ences were statistically significant for the cattle.

Blood, urine and hair mercury concentrationsin garimpeiros, residents of Cachoeiro and thoseliving along the Gurupi River are given in Table5.

4. Discussion

Uncontaminated freshwater mercury concen-trations are < 10 rig/l. Thus, the concentrationsdetermined in the Gurupi and Piria Rivers con-firm significant contamination from the gold re-covery procedures. All the mercury in the water

Table 5Mercury concentrations in human subjects

Sample Group

Blood Garimpeiros(/G/O Villagers

River dwellers(Reference range)

Urine Garimpeiros(M/l) Villagers

(Reference range)

Hair Garimpeiros@pm) Villagers

River dwellers(Reference range)

Reference range from Minoia et al. [14] and Taylor (151.

Rangeof results

2.0-29.32.7-9.61.0-64.71.7-9.9

1.0-1551.0-2.50.1-6.9

0.4-32.00.8-4.60.2-15.0


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68 D. Palheta, A. Taylor /The Scienceof the Tota l Environment 168 1995) 63-69

specimens was in the organic form. These in-creased levels were obtained during the rainy

season when the rivers were exceptionally full andexpansive (several hundred metres wide). Evenhigher concentrations might be anticipated atother times of the year. Levels of up to 600 rig/lwere determined in Minamata Bay while else-where in the Amazonian region, river waters havebeen found with mercury concentrations as highas 8.6 pg/l [6]. The Brazilian National Councilfor the Environment has set a safety limit of 200“g/l, a level which was clearly breached duringthe period of this study. Thus, water used fordrinking, agricultural and recreational purposesrepresents a hazard to the inhabitants of thisarea.

Previous measurements of mercury in fish mus-cle of specimens from uncontaminated rivers wereN 0.06 pg/g. The higher concentrations in someof the fish reported here demonstrate the accu-mulation of mercury from the water, possibly viasmaller aquatic organisms. The major proportionof the mercury in fish was in the organic formindicating probable methylation of the dischargedmercury.

Domestic animals foraging, grazing anddrinking around the contaminated rivers also ac-cumulated mercury, some to much higher concen-trations than in unexposed controls. High levelsin hair are more usually derived from externalcontamination where airborne mercury is in-creased. Mercury in blood reflects recent andcurrent exposure to mercury and as a conse-quence of the foraging and scavenging lifestyle ofthe pigs these animals accumulated more mer-cury, both the test and control groups, than didthe sheep and cattle. The cattle grazing aroundthe river had significantly increased blood mer-cury concentrations compared with the controls.Some of the pigs also had very high (> 50 pg/l)blood mercury levels, but the group data were notsignificantly different from the controls. However,the exposed animals were much younger (< 1year of age) than the controls and would haveaccumulated less mercury from usual dietarysources. The results indicate that mercury accu-mulated in at least some of the domestic animalsand would provide a further source to humans if

used as foodstuffs. Additional measurements inmeat and milk should be undertaken to de-

termine the realistic hazard from these products.The human subjects included in this study wereexposed to several different sources of mercury;amalgam ation and heating processes(garimpeiros), further gold refining activitieswithin the villages, eating of contaminated fishand meat and intake of contaminated river water.Our results confirm that occupationally and non-occupationally exposed subjects accumulate mer-cury, and in discussions with the sampling teamsome individuals described symptoms which wereconsistent with mercury toxicity.

Despite the widespread publicity which has at-tended this topic [12] there are fe w publishedreports of the concentrations of mercury in hu-man subjects living or working in these regions[13]. The results from this study clearly indicatethat widespread environmental contaminationwith mercury exists and that further monitoringof environmental, animal and human specimens isnecessary.

References

RI

t21

131

[41

[51

[61

[71

181

F. Bakir, Methylmercury poisoning in Iraq, Science, 191(1973) 230-241.J.O. Nriagu, The Biogeochemical Cycle of Mercury inthe Environment, N.-Holland/Elsevier, Amsterdam,1979.M. Harada, Minamata disease: organic mercury poison-ing caused by ingestion of contaminated food, in E.P.F.Jelliffe and D.B. Jelliffe (Eds), Adverse Effects of Foods,Plenum Publishing, 1982, pp. 135-148.J.J . Putman, Quicksilver and slow death, Natl. Geo-graphic, October (1972) 507-527.T.W. Clarkson, Mercury poisoning, in S.S. Brown (Ed),Clinical Chemistry and Chemical Toxicity of Metals,Elsevier/N.-Holland, Amsterdam, 1977, pp. 189-200.WC. Pfieffer, Mercury concentrations in inland watersof gold mining areas in Rondonia, Brazil. Sci. TotalEnviron., 87/88 (1989) 233-240.L.D. Lacerda, W.C. Pfieffe r, R.V. Marins, S. Rodrigues,C.M.M. Souza and W.R. Bastos, Mercury dispersal inwater, sediments and aquatic biota o f a gold miningtailing deposit drainage in Pocone, Brazil, Water AirSoil Pollut., 55 (1991) 283-294.L. Magos, Selective atomic absorption determination ofinorganic and methylmercury in undigested biologicalsamples. Analyst, 96 (1971) 847-853.


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[9] L. Magos and T.W. Clarkson, Atomic absorption de-termination of total, inorganic and organic mercury inblood, J. Of f. Assoc. Anal. Chem., 55 (1972) 966-971.

[lo] D.C. Shanna and P.S. Davis, Direct determination ofmercury in blood by use of sodium borohydride, Chn.Chem., 25 (1979) 769-772.

[ill G. Lindstedt, A rapid method for the determination ofmercury in urine, Analyst, 95 (1970) 264-267.

[12] MS. Serrill, The poisoned Amazon, Time, January 10(1994) 30-31.

[13j J. Finkelman, G. Corey and R. Calderon (Eds), Environ-

mental Epidemiology: A Project for Latin America andthe Caribbean, Pan American Center for HumanEcology and Health (WHO), Mexico DF, Mexico, 1993.

[14] C. Minoia, E. Sabbioni, P. Apostoli, R. Pietra, L. Poz-zoli, M. Gallorini, G. Nicolaou, L. Alessio and E.Capodaglio, Trace element reference values in tissuesfrom inhabitants of the European Community. I. Astudy of 46 elements in urine, blood and serum ofItalian subjects, Sci. Total Environ., 95 (1990) 89-105.

[15] A. Taylor, Usefulness of measurements of trace ele-ments in hair, Ann. Clin. Biochem., 23 (1986) 364-378.

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Mercury in Environmental and Biological Samples From a Gold Mining Area in the Amazon Region of Brazil