Indukowane niegenotoksycznymi kancerogenami (NGCs) zmiany metylacji DNA rozpatrywane są jako mechanizm ich toksycznego, w tym rakotwórczego działania. Zbadano wpływ fenobarbitalu (PB), na poziom metylacji regionu promotorowego genu p53 w wątrobie szczurów szczepu Wis tar. Zmiany metylacji genu p53 korelowano z syntezą DNA, aktywnością metylotransferaz DNA (DNMTs) oraz z masą wątroby. Samce szczurów szczepu Wistar otrzymywały PB w dawce wynoszącej 98,2 mg/ kg m.c. x dzień-1 jednorazowo, 3-krotnie i 14-krotnie. Wykazano, że PB wywoływał hipermetylację w badanych sekwencjach rejonu promotorowego genu p53. Indukowana PB hipermetylacja genu występowała w przebiegu całego okresu doświadczalnego. Stymulację syntezy DNA, która poprzedzała wzrost masy wątroby oraz indukcję DNMTs, wykazano tylko po 1 i 3 dawkach związku. Kontynuowanie narażenia zwierząt na PB (14 dawek) nie wywoływało zmian w syntezie DNA i aktywności DNMTs w porównaniu do kontroli. Przypuszcza się, że indukowana PB de novo metylacja rejonu promotorowego genu p53, nie była związana z aktywnością DNMTs.
Dopuszczanie środków ochrony roślin przed ich wprowadzeniem do obrotu i stosowania jest regulowane ujednoliconymi przepisami obowiązującymi na obszarze Wspólnoty Europejskiej. W związku z tym kraje Wspólnoty Europejskiej mają obowiązek wdrażania restrykcyjnych zasad stanowiących podstawę do oceny środków ochrony roślin i określenia ich bezpieczeństwa dla ludzi i środowiska. W artykule przedstawiono aspekty oceny toksykologicznej oraz znaczenie regulacji prawnych obowiązujących we wszystkich krajach członkowskich Unii Europejskiej w procesie rejestracji środków ochrony roślin. Wprowadzenie w procesie rejestracyjnym oceny ryzyka wynikającego z zabiegów środkami ochrony roślin poszerza margines bezpieczeństwa dla użytkowników takich środków ochrony roślin oraz wyznacza nowe standardy bezpieczeństwa w pracach agrochemicznych.
Diklofop, herbicyd z grupy pochodnych kwasu fenoksypropionowego, nie wykazuje właściwości induktorów CYP1A i słabo stymuluje aktywność CYP2B w wątrobie szczura. Natomiast wyniki sugerują, że badany związek hamuje aktywność fenolowej formy UDP-glukuronylotransferazy.
Many environmental factors, including pesticides, cause immunological system disorders by inducing changes in humoral and cellular response. They may stimulate or trigger immunological autoaggression, hypersensitivity and allergy, as well as lead to immunosuppression, thus increasing the incidence of infectious diseases and cancers. Such activity is also attributed to organophosphorus compounds used in agriculture as insecticides, and commonly in households as biocides. The aim of the study was to define possible mechanisms of the immunotoxic activity of the chlorpyrifos (an organophosphorus compound) on experimental animals following their exposure to the compound via the oral route. The present study attempts to define the influence of chlorpyrifos on the profile of subpopulations of immunoactive cells: B, T, CD4+, CD8+, and NK, and on their phagocytic activity in an experimental in vivo model. For this purpose, the Wistar rats, were exposed orally to increasing doses of chlorpyrifos: 0.1 LD50, 0.15 LD50, 0.2 LD50, 0.3 LD50 and 0.4 LD50 for 28 days. In the study animals, we failed to demonstrate a statistically significant decrease in the phagocytic activity of the granulocyte.
Background. Current studies have indicated many environmental factors, such as pesticides, that cause immune system disorders through inducing changes in humoral and cellular responses thereby increasing the risk of contracting infectious diseases and cancer. The literature suggests that low exposures to certain organophosphorus pesticides stimulate the immune system, whilst high exposures result in decreased function. Precise mechanisms for the fall in immunocompetence are often unclear, however it can be predicted that the intimate interaction between the nervous and immune systems can potentially lead to toxicity. Objectives. To determine the effects of organophosphorus pesticide, chlorpyrifos that is often used in Poland, on selected immunological responses, such as immune-competent cell proportions formed experimentally in-vivo by cells of Wistar rats during subchronic exposures after 45 and 90 days. Materials and Methods. The test was carried out on ten male and ten female Wistar rats in each of three test groups, who received 3 chlorpyrifos doses for 90 days intragastrically, according to OECD guidelines (No. 401). Two control groups were given olive oil. After completion, the animals were deeply anaesthetised by a mixture of ketamine (Vetaketam) and xylazine (Vetaxym). Immuno-competent cells were profiled by a commercial monoclonal antibody method. In order to measure the dynamics of any changes, the aforementioned immunological responses were investigated after 45 days using the same procedures for obtaining the relevant biological test material. Results. Test animals exposed to chlorpyrifos had altered number of white bood cells which were either increased or decreased relative to controls after 45 and 90 days for all exposure levels used. Conclusions. The study demonstrated changes in white-blood cell (lymphocyte) response profiles, reflecting an immunomodulation although such changes were equivocal, where both suppression and stimulation were observed.
Background. Faulty but still operating agricultural pesticide sprayers may pose an unacceptable health risk for operators. The computerized models designed to calculate exposure and risk for pesticide sprayers used as an aid in the evaluation and further authorisation of plant protection products may be applied also to assess a health risk for operators when faulty sprayers are used. Obj ective. To evaluate the impact of different exposure scenarios on the health risk for the operators using faulty agricultural spraying equipment by means of computer modelling. Material and methods. The exposure modelling was performed for 15 pesticides (5 insecticides, 7 fungicides and 3 herbicides). The critical parameter, i.e. toxicological end-point, on which the risk assessment was based was the no observable adverse effect level (NOAEL). This enabled risk to be estimated under various exposure conditions such as pesticide concentration in the plant protection product and type of the sprayed crop as well as the number of treatments. Computer modelling was based on the UK POEM model including determination of the acceptable operator exposure level (AOEL). Thus the degree of operator exposure could be defined during pesticide treatment whether or not personal protection equipment had been employed by individuals. Data used for computer modelling was obtained from simulated, pesticide substitute treatments using variously damaged knapsack sprayers. These substitute preparations consisted of markers that allowed computer simulations to be made, analogous to real-life exposure situations, in a dose dependent fashion. Exposures were estimated according to operator dosimetry exposure under ‘field’ conditions for low level, medium and high target field crops. Results. The exposure modelling in the high target field crops demonstrated exceedance of the AOEL in all simulated treatment cases (100%) using damaged sprayers irrespective of the type of damage or if individual protective measures had been adopted or not. For low level and medium field crops exceedances ranged between 40 - 80% cases. Conclusions. The computer modelling may be considered as an practical tool for the hazard assessment when the faulty agricultural sprayers are used. It also may be applied for programming the quality checks and maintenance systems of this equipment.
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