Blood lead levels, δ-ALAD inhibition, and hemoglobin content in blood of giant toad (Rhinella marina) to asses lead exposure in three areas surrounding an industrial complex in Coatzacoalcos, Veracruz, Mexico

Abstract

The Coatzacoalcos Region in Veracruz, Mexico houses one of the most important industrial complexes in Mexico and Latin America. Lead is an ubiquitous environmental pollutant which represents a great risk to human health and ecosystems. Amphibian populations have been recognized as biomonitors of changes in environmental conditions. The purpose of this research is to measure exposure to lead and evaluate hematological and biochemical effects in specimens of giant toads (Rhinella marina) taken from three areas surrounding an industrial complex in the Coatzacoalcos River downstream. Lead levels in toads' blood are between 10.8 and 70.6 μg/dL and are significantly higher in industrial sites. We have found a significant decrease in the delta-aminolevulinic acid dehydratase (δ-ALAD) activity in blood from 35.3 to 78 % for the urban-industrial and industrial sites, respectively. In addition, we have identified a strong inverse relationship between the δ-ALAD activity and the blood lead levels (r = -0.84, p < 0.001). Hemoglobin and mean corpuscular hemoglobin levels, as well as the condition factor, are found to be lower at industrial sites compared with the reference sites. Our results suggest that the R. marina can be considered a good biomonitor of the δ-ALAD activity inhibition and hematological alterations at low lead concentrations.

Monitoring Physiological Responses in Giant Toad (Rhinella marina) from Coatzacoalcos, Mexico: A Comparative Study after 8 Years

“…The giant toad or cane toad (R. marina), Figure 1 is a species of anuran, omnivorous, and opportunistic amphibian [7], with high somatic and hepatosomatic index [8], high biomass, and a voracious appetite [9], which makes it susceptible to the bioaccumulation of organic and inorganic pollutants and their toxicological effects [10,11]. This amphibian is native to South America, Central America, and Mexico [12].…”

“…In Mexico, it is not listed in the species with special protection or in danger of extinction [13]. It has been used as a bioindicator in the evaluation of air pollution [14], infectious diseases [15], organochlorine pesticides [16], endocrine disrupters [17], pollution by lead [11], and other persistent organic pollutants (POPs) [10].…”

“…One of the sites has a higher record environmental pollution is the region of the lower Coatzacoalcos River Basin (Veracruz); region highly impacted due to industrial activities and urbanization that have contributed to the deterioration of ecosystems since the 1960s. Currently, Coatzacoalcos is considered one of the most polluted regions in Mexico [22,23], to such a degree that, in environmental matrices such as water, soil, air, or sediment, and even in fauna, the presence of POPs, volatile organic compounds (VOCs), dioxins, heavy metals, among others, has been detected [11,[24][25][26][27]. Some of these pollutants have been associated with genotoxic or enzymatic effects in aquatic and terrestrial organisms at this site [10,11,28,29].…”

“…Currently, Coatzacoalcos is considered one of the most polluted regions in Mexico [22,23], to such a degree that, in environmental matrices such as water, soil, air, or sediment, and even in fauna, the presence of POPs, volatile organic compounds (VOCs), dioxins, heavy metals, among others, has been detected [11,[24][25][26][27]. Some of these pollutants have been associated with genotoxic or enzymatic effects in aquatic and terrestrial organisms at this site [10,11,28,29]. In this context, the objective of this chapter is to present and compare the results of a monitoring of physiological responses (biomarkers) in R. marina carried out in the lower basin of the Coatzacoalcos river in different years as a follow-up of the environmental quality of the region.…”

Biochemical changes in certain enzymes of Lysapsus limellium (Anura: Hylidae) exposed to chlorpyrifos

“…In addition, we investigated chlorpyrifos (CPF) degradation in water collected from each sampling sited. Enzymatic biomarkers are usually used to detect biological effects of exposure to pesticides on amphibian larvae and adults (Robles-Mendoza et al, 2011;Peltzer et al, 2013;Ilizaliturri-Hernández et al, 2013;Attademo et al, 2014a). These endpoints provide important lines of evidences in ecotoxicological risk assessments (den Besten et al, 2003).…”