Avaliação dos teores de mercúrio em cabelos de adultos residentes da comunidade quilombola de Cocalinho – Maranhão

Abstract

The Quilombola Community of Cocalinho, located in the municipality of Parnarama, Maranhão, has been suffering for some years due to the arrival of agribusiness companies in the surrounding area. Marked by the expansion of eucalyptus and soybean monocultures in the region, Cocalinho faces the consequences of the intensive use of pesticides in these crops, which have caused environmental contamination, loss of local biodiversity, and health problems among the local population, such as the occurrence of skin diseases, respiratory issues, and chronic pain. This context raises concerns about possible exposure to chemical contaminants such as mercury. Metallic mercury is a highly toxic heavy metal with a high degree of danger to humans and is regulated in the national territory regarding its use. In Brazil, in addition to national regulations, there are state and municipal laws that prohibit the commercialization and use of organomercurial pesticides — that is, in their organic form, which is easily absorbed by human tissues. Mercury is bioaccumulative in the body and can be analyzed through hair, considering that this species can bind to this matrix via the bloodstream or through exogenous contamination. One of the techniques used to determine the concentration of mercury is Atomic Absorption Spectrometry (AAS), which relates absorbance to the analyte concentration. To determine the amount of mercury in the samples, Thermochemical Vapor Generation (TVG) was used, with an infrared radiation source coupled to Cold Vapor Atomic Absorption Spectrometry (CVAAS). The analyses quantified low concentrations of mercury in the hair samples, ranging from 5.77 to 27.02 µg kg-1, which are considered tolerable values according to the World Health Organization (WHO), with recommended levels not exceeding 6 micrograms (µg) of Hg per gram (g) of hair. To complement the study, Cu, Ni, Pb, As, and Cd were analyzed using Inductively Coupled Plasma Optical Emission Spectrometry (ICP-OES) in order to quantify the trace levels of these metals in the hair samples. High levels of Cu were quantified, ranging from 7.26 ± 0.62 to 97.53 ± 5.6 mg kg-1, which may be associated with copper-based pesticides used in soybean monocultures that, upon entering the human body, cause symptoms similar to those reported by the families of Cocalinho. Pb concentrations ranged from 0.0269 ± 0.003 to 1.08 ± 0.06 mg kg-1. Only one sample showed Ni levels, with a value of 1.78 ± 0.07 mg kg-1. No signals were detected for As and Cd in the hair matrix. In light of this, it is necessary to expand the analytical possibilities using other techniques and other types of matrices that can be compared with a reference standard, as well as to investigate other possible sources of chemical contamination that may be related to the health complications affecting the population of Cocalinho.