Macrophage activity and histopathology of the lymphohematopoietic organs in male Wistar rats orally exposed to single or mixed pesticides.

The noxious effects of low or effective dose exposure to single or mixed pesticides on macrophage activity and the lymphohematopoietic organs were investigated. Male Wistar rats were orally exposed to dichlorvos, dicofol, endosulfan, dieldrin and permethrin, either as single or combined mixtures during a 28-day study containing eight groups: one group received a semipurified diet (non-treated); two groups received a semipurified diet containing low dose mixture (dieldrin 0.025 mg/kg, endosulfan, 0.6 mg/kg, dicofol 0.22 mg/kg, dichlorvos 0.23 mg/kg, permethrin 5 mg/kg) or an effective dose mixture (dichlorvos 2.3 mg/kg, dicofol 2.5 mg/kg, endosulfan 2.9 mg/kg, dieldrin 0.05 mg/kg and permethrin 25.0 mg/kg), respectively; the other five groups received a semipurified diet containing each single pesticide in effective doses. At sacrifice, the thymus, spleen, mesenteric lymph nodes, Payer's patches and bone marrow were removed for histological analysis. Peritoneal macrophages were obtained to determine the phagocytosis and spreading indexes and tumoral necrosis factor alpha (TNF-α), nitric oxide (NO) and H2O2 production. Exposure to pesticide mixtures did not alter the percentage of macrophage phagocytosis and spreading, TNF-α production or the NO and H2O2 release when compared to the non-treated group. Neither was there any apparent evidence that a pesticide mixture at low or effective doses altered the histological structure of the lymphohematopoietic organs. The findings indicate that short-term treatment with pesticide mixtures did not induce an apparent immunotoxic effect in male Wistar rats.

Ação de mistura de praguicidas no sistema reprodutor de ratos Lewis macho / Mixing action of pesticides on reproduction system of male lewis rats

Levantamento feito pelo Programa de Análise de Resíduos de Agrotóxicos em Alimentos (PARA) apontaram resíduos de agrotóxicos em alimentos frescos à disposição da população brasileira. Esses resíduos apresentaram-se acima do permitido, ou representavam ingredientes ativos não autorizados para determinadas culturas. Situações como estas têm aumentado a preocupação quanto a exposição prolongada de consumidores a múltiplos agentes potencialmente nocivos. Há pouca informação experimental sobre se, e como, exposições múltiplas ou a misturas podem afetar a saúde. O presente estudo objetivou avaliar os efeitos de uma mistura de cinco praguicidas sobre o sistema reprodutor do rato macho. Para compor a mistura que foi adicionada à ração em níveis de NOEL/NOAEL ou LOEL/ LEL/LOAELs, foram selecionados cinco praguicidas cujos resíduos foram detectados em tomates pela ANVISA em 2004. Foram constituídos oito grupos de acordo com o tipo de ração: Grupo 1- ração basal, sem praguicidas; Grupo 2 (“Baixas doses” ou praguicidas de acordo com seus respectivos NOEL/NOAELs) - diclorvós 0,23 mg/kg, dicofol 0,22 mg/kg, endosulfan 0,6 mg/kg, dieldrin 0,025 mg/kg, permetrina 5,0 mg/kg; Grupo 3 (“Doses efetivas”, de acordo com respectivos LOEL/LEL/LOAEL) - diclorvós 2,3 mg/kg, dicofol 2,5 mg/kg, endosulfan 2,9 mg/kg, dieldrin 0,05 mg/kg, permetrina 25,0 mg/kg e Grupos 4 a 8 - rações contendo cada praguicida em separado, em concentrações de acordo com os respectivos LOEL, LEL ou LOAEL. Os animais foram sacrificados no final da 8ª. semana de tratamento. O modelo utilizado permitiu verificar que a mistura em “baixas doses” aumentou o peso relativo dos testículos, mas não causou alterações morfológicas nesse órgão, nem alterou a dinâmica da espermatogênese e função testicular...

Decreased sperm motility in rats orally exposed to single or mixed pesticides.

The Brazilian Agency of Sanitary Vigilance (ANVISA) conducted a study that demonstrated the presence of residues of several pesticides in fresh fruits and vegetables that were available for purchase by the general populace. In order to evaluate potential adverse health effects of low-level exposure to agrochemicals, the reproductive toxicity of the pesticides dicofol, dichlorvos, permethrin, endosulfan, and dieldrin was evaluated in rats dosed with these chemicals individually or as mixtures. Sixty male Lewis rats (6 wk old, 200 x g) were randomly allocated to 8 groups: (1) control group, received basal diet; (2) 5 groups designated a to e received the diet containing each pesticide individually, at the respective effective doses: lowest-observed-adverse-effect level (LOAEL) for dieldrin and endosulfan, lowest-observed-effect level (LOEL) for dicofol, and lowest effect level (LEL) for dichlorvos and permethrin, respectively, depending on the published data; (3) effective dose group, which received a mixture of pesticides added to basal diet at the respective doses reported to produce adverse effects; and (4) low dose group, which received a pesticide mixture added to the basal diet, where each pesticide was at its no-observed-effect level (NOEL). After 8 wk of treatment, reproductive parameters were evaluated. Sperm morphology, daily sperm production (DSP), sperm transit time through the epididymis, hormonal levels, and histopathological evaluation of testis and epididymis did not differ significantly among the groups. However, sperm motility was significantly decreased in animals that received a mixture of dieldrin, endosulfan, dicofol, dichlorvos, and permethrin, as well as in the group receiving dicofol alone. Exposure to the individual pesticides endosulfan, dichlorvos, and permethrin did not markedly affect sperm motility. The impairment of sperm motility in the mixture of pesticides at the NOEL level indicates that reproductive effects not seen with individual pesticides may occur in presence of several pesticides due to an additive effect. However, the pesticide mixtures did not appear to affect DSP or spermatogenesis despite reduced sperm motility.