Cytogenetic damage related to low levels of methyl

mercury contamination in the Brazilian Amazon

MARÚCIA I. M. AMORIM1, DONNA MERGLER2, MARCELO O. BAHIA3

HÉLÈNE DUBEAU4, DANIELA MIRANDA1, JEAN LEBEL2

ROMMEL R. BURBANO1 and MARC LUCOTTE5

1Depto. de Biologia do CCB, Universidade Federal do Pará (UFPA)

2Centre pour l’Étude des Interactions Biologiques entre la Santé et l’Environnement (CINBIOSE)

Université du Québec à Montréal (UQAM)

3Depto. de Patologia do CCB, Universidade Federal do Pará (UFPA)

4Depto. de Ciências Biológicas, Université du Québec à Montréal (UQAM)

5Chaire de Recherche en Environnement H-Q / CRSNG / Université du Québec à Montréal (UQAM)

Manuscript received on May 2, 2000; accepted for publication on July 24, 2000;

presented by Lewis J. Greene

ABSTRACT

The mercury rejected in the water system, from mining operations and lixiviation of soils after deforestation, is considered to be the main contributors to the contamination of the ecosystem in the Amazon Basin.

The objectives of the present study were to examine cytogenetic functions in peripheral lymphocytes within

a population living on the banks of the Tapajós River with respect to methylmercury (MeHg) contamination, using hair mercury as a biological indicator of exposure. Our investigation shows a clear relation

between methylmercury contamination and cytogenetic damage in lymphocytes at levels well below 50 micrograms/gram, the level at which initial clinical signs and symptoms of mercury poisoning occur. The first

apparent biological effect with increasing MeHg hair level was the impairment of lymphocyte proliferation

measured as mitotic index (MI). The relation between mercury concentration in hair and MI suggests that this

parameter, an indicator of changes in lymphocytes and their ability to respond to culture conditions, may be an

early marker of cytotoxicity and genotoxicity in humans and should be taken into account in the preliminary

evaluation of the risks to populations exposed in vivo. This is the first report showing clear cytotoxic effects

of long-term exposure to MeHg. Although the results strongly suggest that, under the conditions examined

here, MeHg is both a spindle poison and a clastogen, the biological significance of these observations are as

yet unknown. A long-term follow-up of these subjects should be undertaken.

Key words: Brazilian Amazon, Mercury, Mitotic Index, Cytogenetics.

INTRODUCTION

Since the late seventies extensive gold mining operations using techniques based on amalgation with

mercury have developed in the Amazon Basin. In

close association with these mining activities, there

Correspondence to: Marcelo de Oliveira Bahia

E-mail: mbahia@ufpa.br

has been important deforestation for population se

tlements and development of agriculture. The me

cury rejected in the water system from mining ope

ations and lixiviation of soils after deforestation 

considered to be the main contributor to the contam

ination of the ecosystem (Roulet et al. 1998a).

Studies conducted in the region of th

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An. Acad. Bras. Ci., (2000) 72 (
498 MARÚCIA I. M. AMORIM et allii

Tapajós River, a major affluent of theAmazon River,

have shown that mercury is present in all environmental compartments (water, soil, plant) (Roulet et

al. 1988b, c; Castilhos et al. 1998, Malm 1998).

The biotransformation of inorganic mercury into

methylmercury in aquatic environments is a well

known process that makes human exposure possible

through consumption of contaminated fish (WHO

1990, 1991). In the region of the Tapajós River,

where fish is the dietary mainstay, methylmercury

exposure levels in humans, measured in hair ranges

from a few μg/g up to 150 μg/g; the median values

reported are in the order of 10 to 20 μg/g (Nakanishi

1992, Pfeiffer et al. 1993, Grandjean et al. 1993,

Lebel et al. 1998).

In vitro studies have shown that methylmercury

is a cytotoxic agent; reduced mitotic index and chromosomal aberrations are induced in human lymphocytes treated in vitro with methylmercury (Bahia et

al. 1999, Nakatsuru et al. 1985, Verschaeve et al.

1985, Betti et al. 1992, 1993a, b). Few studies

have been performed on possible cytotoxic effects

in human populations with methylmercury contamination and authors, reviewing these studies, have

pointed out that the findings are borderline or inconclusive (Nickle 1999, De Flora et al. 1994).

Although there are methodological problems with

each of the studies (small sample size, no control

group, confounding factors not taken into account),

the overall picture suggests that there may be an

association between methylmercury exposure and

cytogenetic deficiencies.

In the early seventies, two studies from Sweden, which included 9 and 23 exposed persons respectively, suggested correlations between blood

mercury levels and lymphocyte structural chromosomal aberrations (Skerving et al. 1970, 1974). In

17 patients with Minamata Disease, Kato and Nakamura (1976) reported a 18.7% frequency of chromosome breakage and a 2.6% frequency of chromosome reunions and rearrangements, however, there

was no control group. A study of 16 fish-eating

subjects from a polluted area in Colombia found

no differences in the frequency of sister-chromatid

exchanges compared to controls; the frequency o

chromosomal aberrations was higher in the expose

group only when achromatic lesions were include

(Monsalve & Chiape 1987). In a larger scale stud

Wulf et al. (1986) analyzed sister-chromatid ex

changes in lymphocytes taken from 147 person

whose diet included seal meat; they showed mea

frequencies 1.7 times higher in the heavy seal-me

eaters as compared to those who ate less; more

over, the frequency of sister-chromatid exchange

increased with increasing blood mercury level

They did not report hair mercury levels, which ma

be a better indicator of longterm exposure.

The objectives of the present study were t

examine cytogenetic functions in peripheral lym

phocytes (mitotic index, polyploidal aberrations an

chromatid breaks) among a population living on th

banks of the Tapajós River with respect t

methylmercury contamination, using hair mercur

as a biological indicator of exposure.

MATERIAL AND METHODS

Population

Cytogenetic study of the analysed population wa

aproved by the Ethics Committees from the Con

selho Nacional de Desenvolvimento Científico e Tec

nológico (CNPq) and the Universidade Federal d

Pará, Belém – Pará, Brasil. The persons who pa

ticipated in this study live in a small village, Brasíl

Legal, situated on the bank of the Tapajos River, a

effluent of the Amazon (3◦59

00S, 55◦3000W

The village is approximately 250 km downstream

from gold-mining operations and the villagers ar

not exposed to mercury vapours. Brasília Le

gal is accessible only by water, a 12 hour boat tri

from Santarém, a city of several hundred thousand

There are minimal health facilities in Brasília Le

gal and electricity for only 3 hours every evening

The adult population (≥ 15 years) is made up o

approximately 250 persons.

Recruitment of study participants was carrie

out from house to house with the help of the loc

community health nursing aides. The study objec

An. Acad. Bras. Ci., (2000) 72 (4)

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CYTOGENETIC DAMAGE DUE TO MERCURY CONTAMINATION 4

tives were explained and villagers were invited to

come to the Health Center where blood and hair

samples were taken, and a questionnaire including socio-demographic information, smoking

and drinking habits, medical and work history was

administered by interview.

A total of 98 adults, ranging in age from 15-81

years, participated in the study. Their age distribution, which is similar to the overall population, is

presented in Table I with other relevant characteristics: sex, smoking and drinking habits, a history of

malaria and previous work in the gold mining region.

For the current smokers, the number of cigarettes per

day ranged from 1 to 4; 4% (3 persons) of the current

drinkers reported drinking more than once or twice

a week and only 2 persons reported previously using marijuana. One third (33.3%) of the men and

two of the women had worked in the gold mining

region, where they would have been exposed to mercury vapours. It is in this area that most of the cases

of malaria were contracted; of the 24 persons with a

history of malaria, 15 (79%) had worked in the gold

mining region.

Cytogenetic Techniques

Blood was obtained in heparinized vacutainers by

venupuncture. In order to avoid potential loss of viability associated with transport and delay, cultures

were prepared on the boat, using electricity provided

by a generator. The blood was stored immediately in

a refrigerator and within a maximum of 4 hours, two

independent cultures were set up by adding 12 drops

of whole blood in 5ml of RPMI 1640 (GIBCO),

containing 20% fetal calf serun (Cultilab) with antibiotics (100 IU penicilin/ml and 100 μg streptomycin/ml, GIBCO) and 4% phytohemoagglutinin

(Cultilab). Cultures were incubated in a controlled

water-bath at 37◦C for 48h. Colchicine (0.8mM,

Sigma) was added to the cultures 2h before harvest

to obtain a maximum of cells at metaphase.

Cells were harvested by centrifugation (1000

rpm/min) and treated during 10 minutes with KCl

(0,075 M, MERCK). They were fixed with Carnoy

fixative 1:3 (glacial acetic acid:absolute methanol).

TABLE I

Characteristics of the study participants.

n %

age category

≥ 15 < 25 35 35.7

≥ 25 < 35 24 24.5

≥ 35 < 45 17 17.3

≥ 45 < 55 12 12.3

≥ 55 10 10.2

sex

women 46 46.9

men 52 53.1

smoking habits

non-smoker 51 52.0

ex-smoker 29 20.4

smoker 27 27.6

alcoholic beverages

non-drinker 37 37.8

drinker 61 62.2

malaria

no 72 74.2

yes 25 25.8

gold mining region

never 78 80.4

yes 19 19.6

Slides were prepared, air-dried and stained for 1

minutes with 3% Giemsa stain (MERCK) diluted 

buffer solution (pH = 6.8).

The slides were analyzed, using light m

croscopy, in the Cytogenetic Laboratory at the Fe

eral University of Pará in Belém, Brazil. For lym

phocyte analyses, one of the two cultures that we

collected for each individual, was selected ra

domly. If the selected culture showed poor prolife

ative potential, the other one was used. At least on

culture was adequate for every person. The mitot

index (MI) (frequency of metaphase nuclei in 100

nuclei) and the number of polyploidal aberration

(PA) in 1000 cell was determined for each indivi

ual. For chromatid breaks, 100 clear metaphas

were analyzed for each culture. The observers we

unaware of subjects’ exposure levels.

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Hair Sampling and Analyses

Hair strands from the root were taken from the occipital region and then placed in plastic bags, with

the root end stapled. Analyses for mercury determination were conducted in the laboratories of the

Environmental Research Chair of the University of

Québec in Montréal, using Cold Vapor Atomic Fluorescence spectrophotometry (CVAF).

Hair strands were cut in one cm segments and

each segment was analyzed for total mercury, according to the procedure described by Bloom and

Fitzgerald (1988) and adapted for hair. Inorganic

mercury determination was done on the first segment

using the methods described by Farant et al. (1981)

and adapted for CVAF. Analytical quality was ensured by including a Health Canada sample of powdered hair in the series. In the present analysis, the

mean value for total mercury of the 2 first centimeters was used.

RESULTS

Hair Mercury Levels

Total hair mercury levels for this population was

log normally distributed and ranged from 0.57 μg/g

to 153.8 μg/g. The latter however was an outlier

and is treated separately in the analyses, the next

highest value was 71.85μg/g. The median level

was 13.50μg/g, with 7.95μg/g and 22.19μg/g, the

25th and 75th quartile values, respectively. Women

have significantly lower levels (median: 10.8μg/g)

as compared to men (median: 17.08μg/g; MannWhitney U = 823.5; p < 0.05). There was no

relation between hair mercury levels and smoking

status, alcohol consumption, age, having worked in

the garimpos or having suffered from malaria.

Mitotic Index

For the participants in this study, the mitotic index

ranged from 8 to 36 per 1000 cells, with a mean

of 25.20 ± 7.8. Table II presents the mean mitotic

indices with respect to the relevant characteristics

of the group. Women had a significantly higher index as compared to men. Although smokers preTABLE II

Mean mitotic index per 1000 cells with respect

to the characteristics of the study participants.

Mitotic Index

mean st. dev.

age category

≥ 15 < 25 26.5 7.8

≥ 25 < 35 24.2 7.4

≥ 35 < 45 22.8 8.7

≥ 45 < 55 23.7 8.3

≥ 55 27.4 7.4

sex

women 27.1 6.8

men 23.2 8.4∗∗

smoking habits

non-smoker 26.0 7.7

ex-smoker 27.3 6.6

smoker 21.5∗ 8.2∗

alcoholic beverages

non-drinker 27.4 6.9

drinker 23.7∗ 8.2

malaria

no 25.7 7.5

yes 22.8 8.5

gold mining region

never 26.0 7.5

yes 22.1 8.6

ANOVA. ∗∗p<0.01; ∗p<0.05.

sented a significantly lower mitotic index as com

pared to ex-smokers and non-smokers, when se

was entered into the model, this difference was n

longer significant (2 factor ANOVA: sex: F = 5.05

p = 0.03; smoking: F = 0.70; ns). The same pa

tern was observed for alcohol consumption, wit

drinkers having a lower mitotic index as compare

to non-drinkers, however, when sex was included i

the model, neither variable was significant (2 facto

ANOVA: sex: F = 1.85; ns; alcohol consumption

F = 1.85; ns). No significant differences were ob

served with age, malaria and having lived in the gol

mining area.

The relation between mitotic index for wome

An. Acad. Bras. Ci., (2000) 72 (4)

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CYTOGENETIC DAMAGE DUE TO MERCURY CONTAMINATION 5

and men with respect to total hair mercury is presented in Figure 1. There appears to be an initial

plateau where mitotic indices vary between 30 and

36; the relation is best described by a second degree

polynomial (r2= 0.64; F = 84.5; p < 0.001) The

outlier (not in the graph), whose HHg is 153.8 μg/g

has a mitotic index of 12.

Polyploides

The frequency of polyploides per 1000 lymphocyte

cells ranged from 0 to 16. The majority of participants (63.9%) did not present this aberration. The

distribution of persons with polyploidal aberrations

(PA) with respect to the characteristics of the group

are presented in Table III. Although proportionally

more men than women presented PA, the difference

did not attain statistical significance. Polyploidal

aberrations were observed significantly more frequently among alcohol drinkers as compared to nondrinkers and among those who had lived in the gold

mining region as compared to those who had not.

When stratified according to sex, these differences

are no longer present.

Figure 2 shows the relation for women and men

for PA frequency and hair mercury level. The lowest level at which PAs are observed is 7.25 μg/g

HHg. Above this level there is an increase in both

the number of aberrations observed as well as the

relative frequency of persons presenting them. Using 7.25 as a cut-off point, the simple regression

line between the frequency of polyploidal aberrations and total hair mercury level is highly significant (r2 = 0.41; F = 51.7; p < 0.001). At HHg ≥

20 μg/g, the prevalence of persons with polyploidal

aberrations is 86.7% as compared to 18.8% for those

with HHg ≥ 10 μg/g <20 μg/g and 8.8% for those

with levels below 10. The differences are highly

significant (Chi square: 48.9, df=2; p < 0.001). A

total of 16 polyploides per 1000 cells were observed

for the outlier.

Chromatid Breaks

Between 1-3 breaks were observed in lymphocytes

for 14 persons (14.6%); for 11 there was only one

TABLE III

Distribution of persons with polypoidal aberrations with respect to the characteristics of

the study participants.

Polyploidal aberrations

n %

age category

≥ 15 < 25 9 25.7

≥ 25 < 35 13 54.2

≥ 35 < 45 7 43.8

≥ 45 < 55 4 33.3

≥ 55 2 20.0

sex

women 12 26.1

men 23 45.1

smoking habits

non-smoker 16 45.7

ex-smoker 6 17.1

smoker 13 37.1

alcoholic beverages

non-drinker 8 21.6

drinker 27 45.0∗

malaria

no 22 31.0

yes 13 52.0

gold mining region

never 23 29.9

yes 11 57.9∗

Chi square: ∗p<0.05.

break, for 2 there were 2 breaks and 1 person pr

sented 3 breaks. The only characteristic that disti

guishes those with breaks from those without is th

level of HHg; those with chromatid breaks hav

significantly higher levels of HHg as compared 

those without (30.46 μg/g ± 10.7 vs 14.5 μg/g 

11.6; ANOVA F=23.3; p<0.001). Among tho

with HHg ≥ 20 μg/g, the prevalence of persons wi

breaks is 37.9%, as compared to 9.4% for those wi

HHg ≥ 10 μg/g < 20 μg/g; none of the persons wi

HHg levels below 10 presented breaks. The diffe

ences are highly significant (Chi square: 19.4, df=

p<0.001).

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An. Acad. Bras. Ci., (2000) 72 (
502 MARÚCIA I. M. AMORIM et allii

Fig. 1 – Relation between mitotic index for men and woman with respect to total hair mercury.

Fig. 2 – Relation for men and woman for polyploidal aberrations frequency and hair mercury level.

DISCUSSION

The findings of this study show a clear relation between methylmercury contamination and cytogenetic damage in lymphocytes at levels well below 50μg/g, the level at which initial clinical signs

and symptoms of mercury poisoning occur (IPC

1990). The first apparent biological effect with in

creasing MeHg hair level was the impairment o

lymphocyte proliferation measured as mitotic index

the proportion of cells in M-phase of the cell cyc

(Rojas et al. 1993). Decreased MI reflects inhibitio

An. Acad. Bras. Ci., (2000) 72 (4)

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CYTOGENETIC DAMAGE DUE TO MERCURY CONTAMINATION 5

of cell-cycle progression and/or loss of proliferative

capacity. During in vitro experiments on chromosomal aberrations, variation in MI is used to monitor induced cellular toxicity. This information on

the degree of cytotoxicity is essential to adequately

select harvest time and test concentration, and is especially important when the results are used in risk

assessment of compounds to which humans may be

exposed. Mitotic index suppression has been suggested for use in dose selection for cytogenetic testing for regulatory purposes (UKEMS 1990). However, this parameter is rarely considered for in vivo

studies.

The relation between mercury concentration in

hair and MI suggest that this parameter, an indicator of changes in lymphocytes and their ability

to respond to culture conditions, may be an early

marker of cytotoxicity and genotoxicity in humans

and should be taken into account in the preliminary

evaluation of the risks to populations exposed in

vivo. In a study of chronic exposure to another metal,

arsenic (As), impairment of lymphocyte proliferation was observed in exposed individuals as compared to controls (Ostrosky-Wegman et al. 1991,

Gonsebatt et al. 1994).

In this Amazonian population, no specific effect of age on proliferative ability of lymphocytes

was observed. These results are similar to other

human studies which reported no variation in lymphocyte proliferative rate with age in a control group

from the United Kingdom (Anderson et al. 1988).

Similarly, the sex-related differences in mitogeninduced lymphocyte proliferation observed here are

in conformity with others. In non-exposed individuals, Anderson et al. (1991), observed higher blastogenic transformation in PHA stimulated lymphocytes from women as compared to men. Although

Gonsebatt et al. 1994 report a greater impairment of

lymphocytes in women exposed to arsenic in drinking water as compared to men, they have no measure

of dose, which may prove to be higher in women.

Sager et al. (1984) reported that the number of cells

in the developing cerebellar external layer in 2-dayold mice was significantly reduced after methylmercury treatment in males but remained unaltered 

females.

The fact that exposure was associated wi

changes in the proliferative potential of lymph

cytes raises the question of possible immunolog

cal implications. There is a large experimental da

base on the immunosuppressive properties of me

als, their inorganic salts and organometallic comp

nents (Koller 1980). Methylmercury, together wi

calcium, lead and As, have shown to cause immun

logical changes in laboratory animals (NRC 1992

The observed reduced lymphocyte proliferation a

sociated with low levels of mercury may transla

into reduced resistance to disease in this Amazonia

population.

The positive results found for polyploidy an

chromatid breaks with mercury exposure and the

appearance following MI perturbations are in agre

ment with the molecular mechanism of action i

ferred from in vitro observations. The genotoxi

ity of mercury is generally attributed to its bindin

with tubulin-SH, causing the impairment of spind

function and chromosome segregational error du

ing cell division (Onfelt 1983, Sager et al. 1983

This has been regarded as the cause of the increase

frequency of polyploidy and aneuploidy in Alliu

and Drosophila (Ramel & Magnusson 1969, 197

Ramel 1969, Fiskesjo 1988). Moreover, in vit

polymerization and depolymerization of micr

tubules is affected by MeHg (Vogel et al. 1985

This could explain some of the multiple effects 

MeHg on the cell cycle, including a lengthened G

and decreased transition probability after short ter

exposure of cycling cells, and a G2 accumulatio

after a longer term exposure (Vogel et al. 1986

Studies on the potentiating effects of organic an

inorganic mercuries on clastogen-induced chrom

some aberrations induced in CHO cells suggest th

they inhibit some of the protein activities involve

in the DNA repair process (Yamada et al. 1993).

The findings of the present study support th

notion that methylmercury has a clastogenic effec

causing chromatid breaks. Mercury like other me

als such as cadmium, chromium, zinc, magnesiu

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504 MARÚCIA I. M. AMORIM et allii

and manganese may be genotoxic through generation of free oxygen radicals (Ochi et al. 1983, Cantoni et al. 1984a, b, Snyder 1988). Methylmercury

is known to generate free radicals through induction

of lipid peroxidation in animal tissue (Ganther 1978,

Shinada et al. 1990). Therefore the observed breaks

could result from free radical damage.

In contrast to inorganic mercury, methylmercury easily passes the placenta barrier at least in

some species. The occurrence of prenatal intoxication in children shows that this is the case also

in humans. It remains to be investigated whether

tissues from exposed fetuses have an increased frequency of cells with polyploids or chromatid

breaks. It is not yet known whether it is associated

with an increased frequency of spontaneous abortions. Theoretically, methylmercury-induced chromosome damage in germline cells could give rise to

abnormal offspring.

This is the first report showing clear cytotoxic

effects of long-term exposure to methylmercury. The group was sufficiently large with a wide

range of mercury exposure, based on a well-known

biological marker, hair mercury. In the situation

of this riverbank population on the Tapajós River,

it is estimated that exposure to mercury has been

present over the past twenty years. Although the results strongly suggest that, under the conditions examined here, MeHg is both a spindle poison and a

clastogen, the biological significance of these observations is as yet unknown. A long-term follow-up of

these subjects should be undertaken. It is noteworthy that lower MIs preceded appearance of chromosomal endpoints such as polyploidy and chromatid

breaks suggesting that MI may prove to be a valuable

early indicator for this health hazard.

ACKNOWLEDGEMENTS

This work was supported by the International Development and Research Center (IDRC) of Canada

as part of the CARUSO project (grant #96-1052-

01/001300-01) and Universidade Federal do Pará.

The authors are grateful to Ms. Glorita Santos,

"Seu" Humberto da Silva, Francisco Borges (i

memoriam), and Ana Maria Rodrigues for technic

help.

REFERENCES

Anderson D, Jenkinson PC, Dewdeney RS, Franc

AJ, GodbertP&Butterworth KR. 1988. Chro

mosome aberrations, mitogen-induced blastogenes

and proliferative rate index in peripheral lymphocyte

from 106 control individuals of the U.K. populatio

Mutat Res 204: 407-420.

Anderson D, Francis AJ, Godbert P, Jenkinson P

& Butterworth KR. 1991. Chromosome aberr

tions (CA), sister-chromatid exchanges (SCE) an

mitogen-induced blastogenesis in cultured peripher

lymphocytes from 48 control individuals sample 

times over 2 years. Mutat Res 250: 467-476.

Bahia MO, Amorim MIM, Burbano RR, Vincent 

& Dubeau H. 1999. Genotoxic effects of mercur

on in vitro cultures of human cells. An Acad Bras C

71(3-I): 437-443.

Betti C, DaviniT&Barale R. 1992. Genotoxic activ

ity of methylmercury chloride and dimethyl me

cury in human lymphocytes. Mutat Res 281: 255

260.

Betti C, Barale R & Pool-Zobel BL. 1993a. Com

parative studies on cytotoxic and genotoxic effects o

two organic mercury compounds in lymphocytes an

gastric mucosa cells of Sprague-Dawley rats. En

Mol Mutag 22: 172-180.

Betti C, Davini T, HE J & Barale R. 1993b. Liq

uid holding effects on methylmercury genotoxici

in human lymphocytes. Mutat Res 301: 267-273.

Bloom N & Fitzgerald WF. 1988. Determination o

volatile mercury species at the picogram level b

low temperature gas chromatography with cold v

por atomic fluorescence detection. Anal Chim Ac

208: 151-161.

Cantoni O, Christie NT, Swann A, Drath DB 

Costa M. 1984a. Mechanism of HgCl2 citotoxi

ity in cultured mammalian cells. Mol Pharmacolog

26: 360-368.

Cantoni O, Christie NT, Robinson SH & Costa M

An. Acad. Bras. Ci., (2000) 72 (4)

AABC 72 4 b 1
CYTOGENETIC DAMAGE DUE TO MERCURY CONTAMINATION 5

1984b. Characterization of DNA lesions produced

by HgCl2 in cell culture systems. Chem Biol Interact

49: 209-224.

Castilhos ZC, Bidone ED & Lacerda LD. 1998. Increase of the background human exposure to mercury

through fish consumption due to gold mining at the

Tapajós River region, Pará State, Amazon. Bull Environ Contam Toxicol 61(2): 202-9.

De Flora S, Benniceli C & Bagnasco M. 1994. Genotoxicity of mercury compounds. A review. Mutat Res

317: 57-79.

Farant JP, Brisset D, Moncion L, Brigasand L &

Chartrand A. 1981. Improved cold vapor atomic

absorption technique for the microdetermination of

total and inorganic mercury in biological samples. J

Anal Toxicol 5: 47-51.

Fiskesjo G. 1988. The Allium test. An alternative in

environmental studies: the relative toxicity of metal

ions. Mutat Res 197(2): 243-60.

Ganther HE. 1978. Modification of methylmercury

toxicity and metabolism by selenium and vitamin E:

possible mechanisms. Environ Health Perspect 25:

71-76.

Gonsebatt ME, Vega L, Montero R, Garcia-Vargas

G, Del Razo LM, Albores A, Cebrian ME &

Ostrosky-Wegman P. 1994. Lymphocyte replicating ability in individuals exposed to arsenic via drinking water. Mutat Res 313(2-3): 293-9.

Grandjean P, Cardoso B & Guimarães G. 1993. Mercury poisoning. Lancet 342: 991.

IPCS (International Programme on Chemical

Safety). 1990. Methylmercury Environmental

Health Criteria, 101. World Health Organization,

Geneva, p. 144.

Kato R & Nakamura A. 1976. Chromosome breakage

associated with organic mercury in human leukocytes

“in vitro” and “in vivo”. Jpn J Human Genet 20:

256-257.

Koller LD. 1980. Immunotoxicology of heavy metals.

Int J Immunopharmacol 2: 269-279.

Lebel J, Mergler D, Branches F, Lucotte M,

Amorim M, Larribe F & Dolbec J. 1998. Neurotoxic effects of low-level methylmercury contam

nation in the Amazonian Basin. Environ Res Sectio

A. 79: 20-32.

Malm O. 1998. Gold mining as a source of mercury e

posure in the Brazilian Amazon. Environ Res 77(2

73-8.

Monsalve MV & Chiappe C. 1987. Genetic effects 

methylmercury in human chromosomes: I. A cyt

genetic study of people exposed through eating co

tamined fish. Environ Mol Mutagen 10: 367-376.

Nakanishi J. 1992. Mercury pollution: Minama

Canada and Amazon. Water Rep 2: 4-5.

Nakatsuru S, Oohashi J, Nozaki H, Nakada S 

Imura N. 1985. Effect of mercurials on lymphocy

functions “in vitro”. Toxicology 36(4): 297-05.

NRC (National Research Council). 1992. Com

mission on Life Sciences, Board on Environment

Studies and Toxicology, Subcommittee on Immun

toxicology Committee on Biological Markers. Bi

logical Markers in Immunotoxicology, NationalAc

demic Press, Washington, D.C., pp. 68-71.

Nickle RA. 1999. Mercury. Top of the hit parade f

eight years. Drug Chem Toxicol 22(1): 129-142.

Ochi T, Takahashi K & Ohsawa M. 1983. A mec

anism for the stimulation by inorganic mercury 

[3H] thymidine incorporation into DNA in cultur

Molt-4F cells. Jpn J Exp Med 53: 187-94.

Onfelt A. 1983. Spindle disturbances in mammali

cells. I. Changes in the quantity of free sulfhydr

groups in relation to survival and C-mitosis in V7

Chinese hamster cells after treatment with colcemi

diamide, carbaryl and ethyl mercury. Chem Biol I

teract 46: 201-17.

Ostrosky-Wegman P, Gonsebatt ME, Montero 

Vega L, Barba H, Espinosa J, Palao A, Cort

nas C, Garcia-Vargas G, Del Razo LM & C

brian M. 1991. Limphocyte proliferation kineti

and genotoxic findings in a pilot study on individu

chronically exposed to arsenic in Mexico. Mutat R

250: 477-482.

Pfeiffer WC, Lacerda LD, Salomons W & Malm 

1993. Environmental fate of mercury from gol

AABC 72 4 b 1

An. Acad. Bras. Ci., (2000) 72 (
506 MARÚCIA I. M. AMORIM et allii

mining in the Brazilian Amazon. Environ Rev 1:

26-37.

Ramel C. 1969. Genetic effects of organic mercury compounds. I. Cytological investigations on Allium

roots. Hereditas 61(1): 208-230.

Ramel C & Magnusson J. 1969. Genetic effects of organic mercury compounds. II. Chromossome segregation in Drosophila melanogaster. Hereditas 61(1):

231-54.

Ramel C & Magnusson J. 1979. Chemical induction

of nondisjunction in Drosophila. Environ. Health

Perspec 31: 59-66.

Rojas E, Herrera LA, Sordo M, Gonsebatt ME,

Montero R, Rodriguez R & Ostrosky-Wegman

P. 1993. Mitotic index and cell proliferation kinetics

for the identification of antineoplastic activity. AntiCancer Drugs 4: 637-640.

Roulet M, Lucotte M, Farella N, Serique G,

Coelho H, Sousa Passos CJ, de Jesus da Silva E,

Scavone de Andrade P, Mergler D, Guimarães

J-RD & Amorim M. 1998a. Effects of recent human

colonization on the presence of mercury in Amazonian ecosystems. Water, Air and Soil Pollution 00:

1-17.

Roulet M, Lucotte M, Saint-Aubin A, Tran S,

Rheault I, Farella N, de Jesus da Silva E,

Dezencourt J, Sousa Passos C-J, Santos Soares

G, Guimarães J-RD, Mergler D & Amorim

M. 1998b. The geochemistry of mercury in central

Amazonian soils developed on theAlter-do-Chão formation of the lower Tapajós River Valley, Pará state,

Brazil. Sci T Env 223: 1-24.

Roulet M, Lucotte M, Canuel R, Rheault I, Tran

S, de Freitas GOG YG, Farella N, Souza do

Vale R, Sousa Passos C-J, de Jesus da Silva E,

Guimarães J-RD, Mergler D & Amorim M. 1998c.

Distribution and partition of total mercury in waters

of the Tapajós River Basin, Brazilian Amazon. Sci T

Env 213: 203-211.

Sager PR & Syversen TL. 1984. Differential responses

to methylmercury exposure and recovery in neuroblastoma and glioma cells and fibroblasts. Exp Neurol

85: 371-82.

Sager PR, Doherty RA & Olmsted JB. 1983. Intera

tion of methylmercury with microtubules in culture

cells and “in vitro”. Exp Cell Res 146: 127-37.

Shinada M, Takizawa Y & Muto H. 1990. Effect o

mercuric chloride on phospholipid peroxidation 

rat. Nippon Koshu Eisei Zasshi 37: 1010-4.

Skerfving S, Hansson K & Lindsten J. 1970. Chro

mossome breakage in human exposed to methylme

cury through fish consumption. Arch Environ Heal

21: 133-139.

Skerfving S, Hansson K, Mangs C, Lindston J 

Ryman N. 1974. Methylmercury-induced chromo

some damage in man. Environ Res 7: 83-98.

Snyder RD. 1988. Role of active oxygen species in met

induced DNA strand breakage in human diploid fi

broblasts. Mutat Res 193: 237-246.

UKEMS. 1990. The third United Kingdom Environmen

tal Mutagen Society collaborative trial. Mutagenes

(Sup. 5): 1-88.

Verschaeve L, Kirsch-VoldersM, Hens L & Susann

C. 1985. Comparative “in vitro” cytogenetic studie

in mercury-exposed human lymphocytes. Mutat Re

157: 221-226.

Vogel DG, Margolis RL & Mottet NK. 1985. Th

effects of methylmercury binding to microtubule

Toxicol Appl Pharmacol 80: 473-86.

Vogel DG, Rabinovitch PS & Mottet NK. 198

Methylmercury effects on cell cycle kinetics. Ce

Tissue Kinet 19(2): 227-42.

WHO, International Program on Chemical Safet

1990. Environmental Health Criteria 101: Methy

mercury. Geneva: World Health Organization, 144

WHO, International Program on Chemical Safet

1991. Environmental Health Criteria 118: Mercur

Geneva: World Health Organization, 168p.

Wulf HC, Kromann N, Kousgaard N, Hansen JC

Niebuhr E & Alboge K. 1986. Sister chromat

exchange (SCE) in Greenlandic Eskimos. Dos

response relationship between SCE and seal die

smoking and blood cadmium and mercury concen

trations. Sci Total Environ 48: 81-94.

An. Acad. Bras. Ci., (2000) 72 (4)

AABC 72 4 b 1
CYTOGENETIC DAMAGE DUE TO MERCURY CONTAMINATION 5

Yamada H, Miyahara T, Kozuka H, Matsuhashi T &

Sasaki YF. 1993. Potentiating effects of organomercuries on clastogen-induced chromosome alterations

in cultured Chinese hamster cells. Mutat Res 290(2):

281-91.

AABC 72 4 b 1

An. Acad. Bras. Ci., (2000) 72 (