Hair as a Biomarker of Long Term Mercury Exposure in Brazilian Amazon: A Systematic Review

Abstract

Many studies have assessed mercury (Hg) exposure in the Amazonian population. This article performs a literature search of the studies that used hair as a biomarker of Hg exposure in the Brazilian Amazonian population. The search covered the period from 1996 to 2016 and included articles which matched the following criteria: (1) articles related to Hg exposure into Brazilian Amazon; (2) articles that used hair as a biomarker of Hg exposure; (3) articles that used analytical tools to measure the Hg content on hair and (4) articles that presented arithmetic mean and/or minimum and maximum values of Hg. 36 studies were selected. The findings show that most of the studies were performed along margins of important rivers, such as Negro, Tapajós and Madeira. All the population presented mean levels of Hg on hair above 6 µg g−1 and general population, adults, not determined and men presented levels of Hg on hair above 10 µg g−1. The results show that most of the studies were performed by Brazilian institutions/researchers and the majority was performed in the State of Pará. The present study identified that Amazonian population has long-term been exposed to Hg. In terms of future perspectives, this study suggests the implementation of a strategic plan for environmental health surveillance in the region in order to promote health and benefit Amazonian population.

Prevalence and factors associated with mercury exposure in riverside communities in the Brazilian Western Amazon

“…Average Hg concentrations higher than those recommended by the Pan American Health Organization (PAHO) were found, limited to 7.0 mg.g -1 , when quantifying hair samples (16) . There are cases that exceed PAHO's limit value by more than 10 times (9) .…”

Health Risk Assessment of Mercury Exposure from Fish Consumption in Munduruku Indigenous Communities in the Brazilian Amazon

“…The cohort studies conducted in the Faroe Islands and New Zealand indicate that even in low doses, the consumption of mercury-contaminated fish during pregnancy can cause important cognitive alterations in children [48,49]. The mercury neurotoxic potential effects in children and adults of the Amazon have been reported in recent publications [50][51][52][53][54]. The most common effects in children are cognitive problems, neurodevelopmental impairment, and psychomotor disorders.…”

Mercury and Prenatal Growth: A Systematic Review

“…First, the heterogeneity of biomarkers used to measure mercury made it difficult to compare results between all studies. We identified two comprehensive reviews of mercury biomarkers which informed our comparisons [ 61 , 62 ], but there is a degree of uncertainty in our current knowledge of how mercury accumulates and is distributed across tissues. Consequently, it was not possible to compare mean mercury concentrations between biomarkers, and we were unable to identify with confidence which study populations experienced the highest levels of prenatal mercury exposure.…”

“…Neonatal hair which begins growing in the third trimester may also be used to identify methylmercury exposure during this time, because hair contains amino acids which readily and permanently bind with MeHg [ 65 ]. Maternal hair which has grown throughout the pregnancy reflects longer-term methylmercury exposure [ 65 ], and it tends to correlate well with maternal and foetal blood Hg [ 61 , 62 ]. Concentrations of Hg in the placenta correlate with foetal Hg, and this matrix is most useful to measure elemental and methylmercury which can both cross the placental barrier [ 68 ].…”