Mercury in Fish-eating Communities of the Andean Amazon, Napo River Valley, Ecuador

Abstract

This exploratory study aimed to examine the relationship between fish eating habits, human mercury levels, and mercury levels in fish in three communities of the Napo River Valley, Ecuadorian Andean Amazon, a region without gold mining but with significant deforestation and volcanic soils with naturally high mercury levels. By recognizing the politicoeconomic factors which cause deforestation, the cultural factors which influence diet, and the biogeochemical factors which contribute to mercury levels, this study employs an ecosystem approach. Interviews on diet were conducted, hair samples from 99 individuals were collected, and samples of commonly eaten fish were taken. Samples were analyzed using cold vapor atomic fluorescence spectrometry (CVAFS). Two rural communities were found to have higher fish consumption and hair mercury levels (8.71 lg/g and 5.32 lg/g) as compared to an urban community (1.87 lg/g). A sequential analysis of hair established mercury levels by month. No seasonal tendencies were noted. Piscivorous fish (0.36 lg/g) were found to be more contaminated in mercury than herbivorous fish (0.05 lg/g). The study shows that sociocultural factors are important in determining mercury exposure. The two village communities consume different species of fish with different frequencies, leading to differential exposure and mercury concentrations in hair samples. The levels of mercury in these two villages were similar to those found in Brazil where neurobehavioral tests showed a correlation between these relatively low levels of mercury and decreased psychomotor capacities. These findings are concerning and should be followed by further studies on the multiple factors that affect the health status of these exposed communities.

Daily mercury intake in fish-eating populations in the Brazilian Amazon

“…During the last decade, a large number of exposure assessments of fish-eating populations have been conducted in different countries of the Amazon (Barbosa et al, 1997;Lebel et al, 1997;Cordier et al, 1998;Dolbec et al, 2001;Santos et al, 2003;Passos et al, 2003a;Gonc¸alves and Gonc¸alves, 2004;Webb et al, 2004;Do´rea et al, 2005;Bastos et al, 2006;Pinheiro et al, 2006). However, little attention has been given to the importance of mercury intake in these populations, although a limited number of studies have tried to estimate the rates of mercury intake Henshel, 1996, 2000;Bidone et al, 1997;Hacon et al, 1997;Kehrig et al, 1998;Fre´ry et al, 2001).…”

Mercury and methylmercury concentration assessment in children's hair from Manaus, Amazonas state, Brazil

“…cited that among fish consumers, riparian communities present the highest degree of exposure, with mean hair-Hg as high as 38.6 ± 14.4 mg kg -1 (Eve et al, 1996) and 65 ± 58 mg kg -1 (Leino et al, 1996). Overall, urban fish-consumers are the least exposed, presenting mean hair-Hg levels of 2.4 mg kg -1 , 2 mg kg -1 (Passos et al 2003), and 1.9 mg kg -1 (Webb et al 2004).…”

Building Capacity in Small-Scale Mining Communities: Health, Ecosystem Sustainability, and the Global Mercury Project

“…Metallic mercury is also transformed into methylmercury in aquatic systems, which becomes biomagnified in the food chain. Local communities reliant on fish, especially carnivorous fish, as a primary food source are particularly susceptible to accumulation of high levels of methylmercury and to neurological damage in cases of acute intoxication (Ikinguara and Akagi, 1996;Mergler 2002;Webb et al, 2004). Methylmercury can also cause sterility and is easily transferred from pregnant women to their fetuses, with effects ranging from spontaneous abortion to neurological symptoms in the child (WHO, 1990).…”