[Toxicology of suicide cases in the state of Rio Grande do Sul, Brazil, 2017 to 2019Perfil toxicológico de los casos de suicidio en Rio Grande do Sul (Brasil), 2017-2019]

Morphometric Evaluation of the Recurrent Laryngeal Nerve of Wistar Rats Exposed to Pesticides

The literature has been shown that exposition by inhalation to chemical compounds can cause vocal disorders and dysphagia in humans, in addition to other symptoms that are manifested according to the type, concentration and duration of exposure to the substance. Cypermethrin and dichlorvos are pesticides widely used in agriculture, public health, veterinary, and home environments. Despite the scientific evidence that cypermethrin and dichlorvos can cause neurodegenerative damage and motor alterations, there are no studies evaluating the toxic effects of these pesticides on the morphology of structures responsible for vocal mobility, especially to the Recurrent Laryngeal Nerve (RLN). Considering the association between vocal disorders in humans and variations in RLN and morphometry, the aim of this study was to evaluate the possible alterations in the microstructure of RLN secondary to subchronic exposure to cypermethrin (pyrethroid) and dichlorvos (organophosphate) in Wistar rats. The experimental protocol (approved by CEUA-UFCSPA: 321/15 and 323/15) consisted of 15 male Wistar rats, allocated in 3 groups: Control (n = 5, exposed to water), Cypermethrin (n = 5, exposed to cypermethrin - 1/10 of the inhalation median lethal concentration [LC50] - 0.25 mg/L) and dichlorvos (n = 5, exposed to dichlorvos - 1/10 of the LC50 - 1.5 mg/L). Inhalation exposure was performed for 4 hours, 5 times per week, for 6 weeks. The nerves were collected, histologically processed and analyzed using morphometric parameters measured using ZEN 2.6 (Zeiss - Germany). The cypermethrin and dichlorvos groups showed significant changes (P < 0.001, ANOVA) in the g-ratio and in the thickness of the myelin sheath of the RLN when compared to the control animals, however, none of the other parameters evaluated showed statistically significant differences. These findings indicate that repeated inhalation exposure to commercial products of cypermethrin and dichlorvos is able to modify the structure of the RLN and possibly generating vocal changes and / or dysphagia.

Characteristics of deaths by suicide in postmortem studies in Brazil: A systematic review and meta-analysis

INTRODUCTION

Suicide is one of the leading causes of death, with a trend for its increase in Brazil in past decades. This study aimed to review the characteristics of suicides in Brazilian postmortem studies.

METHODS

Studies investigating suicide deaths in Brazil, and based on autopsy or psychological autopsy were included. Proportions were pooled across studies with the use of random and fixed effects models.

RESULTS

6777 references were retrieved from six databases (searches up to January, 2023), and 45 studies included. In autopsy studies (k = 37, n = 16,231), substance use at toxicological analysis was found in 36.42% of cases (95% CI: 30.05-43.32), previous suicide attempts in 23.92% (95% CI: 6.73-57.78). In psychological autopsy studies (k = 8, n = 139), previous suicide attempts were reported in 28.09% (95% CI: 19.74-38.28), psychiatric conditions/symptoms in 90.67% (95% CI: 67.79-97.82), family history of suicidality in 21.33% (95% CI: 13.5-32.03). Most suicide deaths were reported in males and took place at the victim's home, hanging was the most frequent suicide method. Included studies presented significant limitations in quality assessment.

CONCLUSION

Future studies should present more robust methodology, including bigger samples, the use of controls, and validated methodology.