Evaluation of the effects of exposure to heavy metals in rescue dogs and their role as environmental biomonitors after the Brumadinho disaster, Minas Gerais, Brazil

In January 2019, a mining dam collapsed in Brumadinho, Minas Gerais, Brazil. Numerous professionals from fire brigades from several states in Brazil and trained dogs worked to rescue the victims of this tragedy and maintained direct contact with the dam's tailings. To understand the consequences generated by this exposure, a cross-sectional observational study, heavy metals, cytokines and clinical signs were correlated, was carried out with the aim of identifying biological biomarkers and the presence of metals in trained dogs. Hair and serum samples from 30 rescue dogs from the Military Fire Brigade were used to analyze heavy metals, trace elements and cytokines. Among these, 20 dogs were exposed to tailings and 10 were not involved in mining disasters. Cadmium metal obtained a significant result (p = 0.013) when compared with the exposure to waste and a negative correlation (-0.58) with IL-15 (p = 0.01). The clinical signs that presented significant values were dermatological (p = 0.011) and locomotor (p = 0.003). Of the exposed dogs (6/20) 30 %, had neoplasms in the skin and reproductive system. The dogs in the exposed group showed a positive correlation (0.49) between Lead and the number of hours worked (p = 0.02) and a positive correlation (0.48) with Chromium (p = 0.03). The correlation between clinical signs, presence of metals and inflammatory cytokines indicates that dogs can be a promising tool for characterizing long-term occupational exposures and highlights the importance of biomonitoring the health of firefighters who suffer constant environmental exposures.