The Science of the Total Environment 289 Ž2002. 41᎐47
Human exposure to mercury in San Jorge river basin,
Colombia ž South America/
Jesus OliveroU , Boris Johnson, Eduardo Arguello
En¨ ironmental and Computational Chemistry Group, Uni¨ ersidad de Cartagena, A.A. 6541, Cartagena, Colombia
Received 12 June 2001; accepted 7 August 2001
Abstract
During May᎐September 1999 human hair samples were collected from the village of Caimito, a fishing community
of the state of Sucre ŽColombia., in the San Jorge River basin area, and analyzed for total mercury Žt-Hg. by cold
vapor atomic absorption spectroscopy. T-Hg was measured in both male and female people aged 15᎐65 years, whose
diet mainly consists of fish collected in nearby marshes. Average hair t-Hg concentration in people from Caimito was
4.91" 0.55 ␮grg Ž n s 94., similar to the value previously detected in fishermen living in the gold mining area, 50 km
east. Males had similar t-Hg concentrations Ž4.31" 0.42 ␮grg; n s 56. to females Ž5.78" 1.21 ␮grg; n s 38. and
there was no difference in t-Hg levels between groups of different age. Mercury content in hair was weakly but
significantly associated Ž R s 0.20, Ps 0.05. with fish consumption. 䊚 2002 Elsevier Science B.V. All rights reserved.
Keywords: Mercury; Hair; River; Fish; Colombia
1. Introduction
Mercury ŽHg. is a recognized environmental
contaminant since the Minamata disaster in the
late 1950s. The incorporation of any Hg species in
aquatic environments results in the biotic and
abiotic formation of methylmercury, a highly toxic
U
Corresponding author. Tel.: q11-57-5669-8179; fax: q1157-5669-8323.
E-mail address: [email protected] ŽJ. Olivero..
compound that is accumulated by fish. Humans
can absorb Hg through placental exposure, ingestion of mother’s milk and fish consumption
ŽBoischio and Henshel, 1996.. Toxicity associated
with Hg depends on the metal species. Exposure
to inorganic Hg induces color vision loss ŽCavalleri and Gobba, 1998., peripheral neuropathy
ŽChu et al., 1998., while organic Hg has been
associated with teratogenicity ŽLeonard et al.,
1983; De Flora et al., 1994. and neurotoxicity
ŽLebel et al., 1996; Murata et al., 1999; Myers et
al., 1995., particularly during late gestation
0048-9697r02r$ - see front matter 䊚 2002 Elsevier Science B.V. All rights reserved.
PII: S 0 0 4 8 - 9 6 9 7 Ž 0 1 . 0 1 0 1 8 - X
42
J. Oli¨ ero et al. r The Science of the Total En¨ ironment 289 (2002) 41᎐47
ŽGrandjean et al., 1999.. Hg toxicity derived from
fish consumption is a potential threat to public
health that has made necessary its monitoring in
the environment. Analysis of Hg in hair of the
exposed population helps to establish the actual
risk of Hg intake due to the consumption of
contaminated fish, the main source of mercury in
the diet ŽWHO, 1991.. In Colombia, mercury
contamination has been associated with informal
sector gold mining activities, where the metal is
released into the water during gold extraction and
into the atmosphere after amalgam burning. This
process has lead to mercury accumulation in fish
and humans living in this area ŽOlivero et al.,
1995; Olivero and Solano, 1998.. The objective of
this study was to document the t-Hg contents in
the human community living in the village of
Caimito, state of Sucre, Colombia. Caimito is
located approximately 50᎐100 km west the larger
gold mining zone in this country, the South of
Bolıvar,
and apparently there are no gold extrac´
tion activities in this area. Therefore, these study
provided the opportunity to collect hair t-Hg data
from fish-eating people living in a watershed with
low Hg incorporation from gold mining activities.
2. Materials and methods
2.1. Sample collection and handling
Hair samples were collected from sites in the
San Jorge river basin area located near the village
of Caimito between May and September, 1999.
This village is located in northwestern Colombia
Ž8⬚46⬘᎐8⬚48⬘ N and 75⬚6⬘᎐75⬚8⬘ W.. Fishing and
agriculture are the major economic activities for
people from this locality. Hair samples were collected from 94 people aged 15᎐65 Ž37.3" 14.9.
years who gave their consent for interviews and
sample collection after contacting them through a
community leader. Hair samples were cut from
the occipital region and stored in white envelopes. In the lab, samples were washed with
neutral detergent and air-dried. A standardized
questionnaire was used to interview the participants in this study ŽKiesswetter et al., 1997.. Demographic information, dietary habits, occupatio-
nal history, lifestyle and possible neurological
symptoms of Hg poisoning were recorded during
an interview before hair collection. Previous studies have shown a relationship between Hg and
heart disease ŽSalonen et al., 1995.. Accordingly,
blood pressure measurements were conducted as
a marker of cardiovascular function.
2.2. Mercury analysis
Total Hg analysis was performed by cold vapor
atomic absorption spectroscopy after acid digestion as previously reported ŽSadiq et al., 1991..
Quality control procedures included the analysis
of blank samples, precision and accuracy measurements through the analysis of the standard
reference material Dorm-1. The t-Hg concentration obtained for the certified material was 4.1"
0.5 ␮grg Žcertified value s 4.6" 0.3 ␮grg.. The
detection limit, defined as three times the standard deviation of the blank was 0.024 ␮grg.
2.3. Statistical treatment of data
Data are presented as mean " standard error
of duplicate determinations. In samples below the
detection limit, a mean value equal to half of the
detection limit value was used to include all the
collected data in the statistical analysis ŽBatzevich, 1995.. The Kolmogorov᎐Smirnov test was
used to test for normal distribution. Because most
of the samples did not follow a normal distribution, t-Hg data were log transformed and the
evaluations of the differences between mean t-Hg
concentrations were performed using ANOVA.
Comparisons between two groups were done using the Student’s unpaired t-test. To assess correlations between variables Spearman rank order
test was used. For all statistical analysis, the criterion for significance was P- 0.05.
3. Results
Hair t-Hg concentrations in people from
Caimito grouped by age are shown in Fig. 1. The
average t-Hg concentration for all hair samples
was 4.91" 0.55 ␮grg. Differences among age
J. Oli¨ ero et al. r The Science of the Total En¨ ironment 289 (2002) 41᎐47
Fig. 1. Concentration of total Hg in hair for people from
Caimito grouped by age. Data are presented as boxplots,
where solid lines indicate Žfrom bottom to top. the 10, 25, 50
Žmedian., 75 and 90th percentiles, respectively. Black circles
are outliers.
groups were not significant as shown by ANOVA
Ž P) 0.05.. There was no statistical difference Ž P
s 0.697. between Hair t-Hg concentrations in
males Ž4.31" 0.42 ␮grg; median: 3.095 ␮grg;
n s 56. and females Ž5.78" 1.21 ␮grg; median:
3.741 ␮grg; n s 38.. Most t-Hg concentrations
varied between 0.5 and 10 ␮g Hgrg. One subject
had higher hair t-Hg than the remaining 94 subjects. His hair t-Hg was 340 ␮grg and was not
included in the statistical analysis.
A weak but significant correlation was observed
between frequency in fish consumption and hair
t-Hg concentration Ž R s 0.20, Ps 0.05. as shown
in Fig. 2. No correlations were found between
t-Hg in hair and age Ž R s y0.02, Ps 0.79. or
blood pressure Žsystolic: R s y0.103, Ps 0.320;
diastolic: R s y0.054, Ps 0.605.. Interestingly,
some correlations were observed for t-Hg in hair
and qualitative subjective symptoms such as frequency of coughing Ž R s 0.270, Ps 0.01., emotional unstability Ž R s 0.230, Ps 0.03., and in a
less extent with stomachache Ž R s 0.181, Ps
0.081..
43
to determine the impact of gold mining in the
environment of ecosystems in Colombia. In this
regard, we have previously reported Hg concentrations in environmental and human samples in
the gold mining area ŽOlivero et al., 1995, 1997;
Olivero and Solano, 1998.. One particular concern
has been to establish if mercury contamination
exists in sites without marked gold mining activity. Caimito is located on the San Jorge river
basin, approximately 50 km west from the main
gold mining area in Colombia, the South of
Bolıvar.
Although the San Jorge River watershed
´
is not used for gold extraction, nickel and iron
mining are extensive upstream this waterbody.
Hair t-Hg concentrations found in Caimito were
similar to those found in fishermen from the gold
mining area in Colombia but greater than those
found in Cartagena ŽOlivero et al., 1995., a coastal
city located approximately 280 km downstream
the gold mining area. Table 1 shows different
reports of hair Hg concentrations for people from
different countries. Remarkably, hair t-Hg levels
in people from Caimito were much lower than
those found in gold mining sites in Brazil but
similar to those reported for fishermen living in
low polluted places. According to this literature
review, gold mining together with chlor-alkali
plants are the main important sources of mercury
contamination around the world. In fact, the
greater mercury levels in hair samples have been
4. Discussion
The major goal of our research group has been
Fig. 2. Total Hg in hair vs. fish consumption for people from
Caimito.
44
J. Oli¨ ero et al. r The Science of the Total En¨ ironment 289 (2002) 41᎐47
Table 1
Hair mercury levels in people from different countries
Country
Bangladesh
wTotal Hg in hairx
a
0.44" 0.19 ␮grg
0.02᎐0.95 ␮grgb
n s 219c
1.51᎐59.01 ␮grg
21% having less than 10 ␮grg
Brazil
ŽAmazon,
Negro river.
Brazil
9.0 ␮grg
ŽAmazon,
Tapajos river.
Brazil
Brasilia Legal: 11.75" 7.95 ␮grg Ž n s 220.
ŽAmazon,
Sao Luis do Tapajos:
´ 19.91" 11.96 Ž n s 327.
State of Para
´. Santana de Ituqui: 4.33" 1.94 Ž n s 321.
Brazil
Fishermen: 23.9" 9.3 ␮grg Ž n s 11.
ŽAmazon,
Other men: 14.3" 9.4 ␮grg Ž n s 34.
Tapajos River. Women: 12.6" 7.0 ␮grg Ž n s 46.
Brazil
6.54" 5.45 ␮grg
ŽAmazon,
n s 53
Balbina Reservoir.
Brazil
34.2 ␮grg
ŽAmazon,
n s 55
Tapajos river.
Brazil
25 ␮grg
ŽAmazon,
Maximum: 151 ␮grg
Tapajos river.
Brazil
4.3 ␮grg
ŽAmazon region.
Brazil
65 ␮grg
ŽTucurui water 0.9᎐240 ␮grg
reservoir.
Brazil
16.6" 10.5 ␮grg
ŽAmazon.
Canada
Sportfishers
ŽMontreal.
Vietnamese: 1.2 ␮grg Ž n s 9.
Bangladeshis: 1.1 ␮grg Ž n s 9.
Majority-community: 0.7 ␮grg Ž n s 25.
China
1.69" 4.98 ␮grg
ŽHarbin.
0.11᎐36.3 ␮grg
n s 64
China
Fertile: 3.3 ␮grg Ž n s 49.
ŽHong Kong.
Subfertile: 4.23 ␮grg Ž n s 117.
Vegetarians: 0.4 ␮grg Ž n s 16.
Colombia
Fishermen: 5.23" 5.78 ␮grg
ŽBolivar.
Miners: 2.83" 3.27 ␮grg
Other activities: 2.40 " 2.02 ␮grg
Colombia
4.91" 0.55 ␮grg
ŽSucre.
Ž n s 94.
French Guyana
Pregnant woman: 1.6 ␮grHgrg
Other adults: 3.4 ␮grg
Children: 2.5 ␮grHgrg
Indonesia
3.13" 4.7 ␮grg
ŽMedan.
0.20᎐19.89 ␮grg
n s 55
Remarks
Reference
Fish consumption
Holsbeek et al. Ž1996.
Fish-eating population
Barbosa et al. Ž2001.
Gold mining
Dolbec et al. Ž2000.
Brasilia Legal and Sao Luis do Tapajos
´
are located in the gold mining area
Santana de Ituqui is not in this area
250 km downstream from gold mining
area
Santos et al. Ž2000.
Lebel et al. Ž1998.
Reservoir with no known gold mining
Kehrig et al. Ž1998.
Gold mining
Barbosa et al. Ž1997.
Gold mining
Malm et al. Ž1995.
Gold mining
Palheta and Taylor
Ž1995.
Leino and Lodenius
Ž1995.
Gold mining
Gold mining
Akagi et al. Ž1994.
Hg levels associated with
fish consumption
Kosatsky et al. Ž1999.
Exposure to inorganic Hg from
occupationalrenvironmental source
Feng et al. Ž1998.
Fish, major source of Hg
Gold mining area
Dickman and Leung
Ž1998.;
Dickman et al. Ž1998.
Olivero et al. Ž1995.
San Jorge river basin area
Village of Caimito
Fish consumption
Olivero et al. Ž2001.
ŽThis study.
Cordier et al., 1998
Exposure to inorganic Hg from
occupationalrenvironmental sources
Feng et al. Ž1998.
J. Oli¨ ero et al. r The Science of the Total En¨ ironment 289 (2002) 41᎐47
45
Table 1 Ž Continued.
Country
wTotal Hg in hairx
Remarks
Reference
Japan
41 ␮grg
Estimated from methylmercury in
cord tissue
Mothers with children having congenital
or infantile Minamata disease
Neurological subjective symptoms
of Minamata disease
Fish and shellfish major sources of Hg
Akagi et al. Ž1998.
Diseased people Žnot including
Minamata disease.
Nakagawa Ž1995.
21.9 ␮grg
3.7᎐71.9 ␮grg
3.5 ␮grg
0.13᎐13 ␮grg
0.38" 0.32 ␮grg
Fish consumption
Abe et al. Ž1995.
Artisanal gold mining
Appleton et al. Ž1999.
People who died suddenly
Hac et al. Ž2000.
10.39" 6.85 ␮grg
1.93᎐42.61 ␮grg
n s 181
0.77 ␮grg n s 233
0.18᎐2.44 ␮grg
0.947 ␮grg n s 29
0.16᎐5.4 ␮grg
Pregnant women
Exposure through Hg-contaminated
sea food
School children. Hg levels correlated
with seafood consumption
Gold fields. Low levels of Hg in hair
consistent with low Hg levels in
consumed fish
Renzoni et al. Ž1998.
Japan
ŽMinamata.
Japan
ŽTokushima.
Japan
ŽTokyo and
surroundings.
Papua New Guinea
ŽLake Murray.
Philippines
ŽMindanao Island.
Poland
ŽGdansk.
Portugal
ŽMadeira.
Spain
ŽTarragona.
Tanzania
ŽLake Victoria.
3.8᎐133 ␮grg
n s 24
Male: 5.0" 3.4 ␮grg n s 83
Female: 2.1" 1.1 ␮grg n s 108
4.62" 2.75 ␮grg
0.63᎐24.64 ␮grg
n s 243
2.08" 36.5 ␮grg
n s 133
Harada et al. Ž1998.
Feng et al. Ž1998.
Batista et al. Ž1996.
Ikingura and Akagi
Ž1996.
a
Mean or median.
Range.
c
Sample number.
b
found in people living in Brazil, where gold mining is extensive ŽMalm, 1998.. Other countries
where mercury levels in hair are considerable
high are Japan, Papua New Guinea and Portugal.
It is clear that even for relatively low-contaminated places, hair Hg may correlate with fish
consumption, as observed in this work. However,
high Hg concentrations in hair do not depend
solely on fish consumption frequency. Average
t-Hg levels in fish from Caimito were below 0.5
␮grg, and the fish with the higher consumption
frequency, the phytoplanktivore Prochilodus magdalenae, had a mean t-Hg concentration not
greater than 0.1 ␮grg ŽPaz, 2000.. This observation might account for the low observed correlation between T-Hg in hair and fish consumption.
Despite the low levels of hair t-Hg, the mild
association observed between emotional unstability and hair t-Hg concentration is a qualitative
indication that additional data should be collected to establish possible neurological damage
related to Hg poisoning among the people from
Caimito. Several authors have suggested that hair
Hg levels below 10-20 ␮g Hgrg, as those found in
this study, could induce subtle neurotoxic effects
such as neurobehavioral and motor dysfunction
ŽDolbec et al., 2000; Harada et al., 1998; Grandjean et al., 1998., as well as affect fetal brain
development ŽMyers and Davidson, 2000.. People
from Caimito depend on fishing for both local
consumption and as an economical activity. Frequently, fishermen drink water directly from the
marshes or the river. These waterbodies usually
receive sewage from cities and communities upstream without any treatment, a common practice
all over the country, and consequently, it is common the presence of intestinal parasites in these
people. The low but positive correlation between
46
J. Oli¨ ero et al. r The Science of the Total En¨ ironment 289 (2002) 41᎐47
coughing and stomachache, two signs of Ascaris
infections ŽHlaing et al., 1990., and mercury levels
in hair, may be the result of the poor sanitary
conditions present in these communities.
5. Conclusions
Hair t-Hg mercury levels in people from the
San Jorge River basin were similar to those found
by Olivero et al. Ž1995. in people living in the
gold mining area in Colombia. Data analysis suggested the source of mercury was the fish consumption. Mercury monitoring and neurological
studies should be conducted to assess the impact
of mercury intake by fish consumption in the
health of people from Caimito.
Acknowledgements
This work was sponsored by ORCYTrUNESCO, Montevideo ŽUruguay. and the Universidad de Cartagena. The authors thank the people
of Caimito, and also Claudia Mendoza, Rafael
Olivero, Adolfo Consuegra, Roberto Hurtado,
Ana Gutierrez, and Beatris Solano and for their
assistance during sampling collection and mercury analysis.
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