Levels of Total Mercury and Health Risk Assessment of Consuming Freshwater Stingrays (Chondrichthyes: Potamotrygoninae) of the Brazilian Amazon

Abstract

Mercury is an element with potential risk to fish and those who consume it. Thus, this study aimed to determine the levels of total mercury (THg), carry out a health risk assessment related to the consumption of the freshwater stingrays Potamotrygon motoro, and determine the physical and chemical properties of the water where stingrays occur. Stingrays of the species P. motoro were obtained from the Amazon River, and samples of the animals’ musculature were collected to determine THg levels. Risk assessment was conducted using pre-established formulas of estimated monthly intake (EMI), maximum monthly intake rate (IRmm), and hazard quotient (HQ). Three population scenarios were evaluated, considering both sexes and differences between rural and urban areas. There was no relationship between weight and THg concentration nor between total length and THg concentration. Higher EMI values were observed in rural children; for the IRmm, male children had the lowest consumption levels. For the hazard quotient, there was a similarity between the three age groups when comparing the male and female sexes. In addition, the representatives of the rural area always had lower values than the urban area. Freshwater stingrays, like other elasmobranchs, can be crucial animal species because they act as sentinels in studies that assess harmful chemicals like mercury.

Trends in Mercury Contamination Distribution among Human and Animal Populations in the Amazon Region

“…Floodplain areas were specifically included in the analysis to represent zones of high water retention and the accumulation of mining tailings, which are factors that can contribute to Hg concentrations in the environment [ 84 , 156 ]. Notably, the extent of illegal mining is more widely recognized by initiatives such as RAISG, the data from which indicate an overlap of these activities with the studied areas.…”

Hematological and plasma biochemical profile of two species of freshwater stingrays from the Amazon

“…Due to their high biodiversity and complex polychromatism patterns, these organisms have shown high potential for the aquarium hobby, which is highly coveted in countries such as the United States, Japan, Taiwan, and Germany (Lasso et al 2016). Furthermore, stingrays are also being used as a food source ), and investigations have been carried out on consumption risk analysis in the assessment of mercury (Oliveira et al 2023) and the detection of fraud in the marketing of freshwater stingrays, which are traditionally marketed as being of the genus Potamotrygon, but are Paratrygon aiereba (Andrade et al 2023), which is a critically endangered species (MMA 2022).…”

Occurrence of Four Freshwater Stingrays (Chondrichthyes: Potamotrygoninae) in the Uatumã River Basin, Amazon Region: A Field Study

“…In recent years, there have been significant advances in studies of freshwater stingrays, including studies on contaminants [19], the determination of stingray meat using low-cost analytical tools [20], blood physiological assessment in a natural environment [21][22][23], and blood parasite records [24,25]. Still, despite these studies, most Potamotrygonines are listed as Data Deficient on the IUCN List of Threatened Species due to a lack of information on population rates and geographic dispersion [26].…”