Zinc Ameliorate Oxidative Stress and Hormonal Disturbance Induced by Methomyl, Abamectin, and Their Mixture in Male Rats.

Exposure to mixtures of toxicants (e.g., pesticides) is common in real life and a subject of current concern. The present investigation was undertaken to assess some toxicological effects in male rats following exposure to methomyl (MET), abamectin (ABM), and their combination (MET+ABM), and to evaluate the ameliorative effect of zinc co-administration. Three groups of rats were designated for MET, ABM, and the mixture treatments. Three other groups were designated for zinc in conjunction with the pesticides. Additionally, one group received water only (control), and the other represented a positive zinc treatment. The obtained results revealed that MET was acutely more toxic than ABM. The tested pesticides induced significant elevation in lipid peroxidation and catalase levels, while declined the levels of the other tested parameters e.g., Superoxide dismutase (SOD), Glutathione-S-transferase (GST), Glutathione peroxidase (GPx), Glutathione reductase (GR), Cytochrome P450 (CYP450), testosterone, and thyroxine). Biochemical alterations induced by the mixture were greater than those recorded for each of the individual insecticides. The joint action analysis, based on the obtained biochemical data, revealed the dominance of antagonistic action among MET and ABM. Zinc supplementation achieved noticeable ameliorative effects. It was concluded that zinc may act as a powerful antioxidant, especially in individuals who are occupationally exposed daily to low doses of such pesticides.

In vivo antitumour potential of camel's milk against hepatocellular carcinoma in rats and its improvement of cisplatin renal side effects.

CONTEXT: Camel milk (CM) is recommended for liver disease patients in Egypt for a strong belief that it has a curative effect. OBJECTIVE: The effect of consumption of CM with or without chemotherapeutic drug cisplatin was evaluated on induced hepatocarcinogenesis in rats. MATERIALS AND METHODS: Wistar male rats (56) were divided into eight groups (7 rats each). Group I was control. Hepatocarcinogenesis was initiated by a single dose of intraperitoneal injection of diethylnitrosamine (DENA) (200 mg/kg BW) and promoted by phenobarbitone (500 ppm) in drinking water in groups V, VI, VII and VIII. Treatment started from 28th till 38th week using CM (5 mL/day) and/or cisplatin (5 mg/kg/3 weeks) in groups II, III IV, VI, VII and VIII. Biochemical analysis, lipid peroxidation and superoxide dismutase (SOD) activity in liver tissue were performed. Histopathology of liver and kidney and immunohistochemistry of placental glutathione-S-transferase (P-GST) in liver were performed and analyzed using image analysis. RESULTS: Albumin concentration and SOD activity were 3.13 ± 0.23 and 311.45 ± 41.71 in group VII (DENA & cisplatin), whereas they were 4.3 ± 0.15 and 540.5 ± 29.94 in group VII (DENA, CM and cisplatin). The mean area of altered hepatocellular foci and P-GST altered foci decreased in group VI (DENA and CM) (1049.6 ± 174.78 and 829.1 ± 261) and group VIII (cisplatin and CM) (1615.12 ± 436 and 543.9 ± 127) compared to group V (DENA only) (4173.74 ± 510.7 and 3169.49 ± 538.61). Cisplatin caused chronic interstitial nephritis, which was slightly alleviated in group VIII (CM and cisplatin). CONCLUSIONS: CM had an antioxidant effect and together with cisplatin managed to decrease hepatocarcinogenesis.

Which exposure stage (gestation or lactation) is more vulnerable to atrazine toxicity? Studies on mouse dams and their pups.

Either during gestation or lactation, the experimental mouse dams received one of the following treatments: (a) diet free of pesticide; (b) diet enriched with atrazine (ATZ); 31.0 µg kg-1; (c) diet free of pesticide + oral vitamin E (α-tocopherol; 200 mg kg-1 per mouse); and (d) diet enriched with ATZ (31.0 µg kg-1) + oral vitamin E (200 mg kg-1 per mouse). At the weaning, pups and dams were killed and selected organs and blood samples were collected for analyses. Compared with the control results, ATZ induced alteration in a number of biochemical and histopathological parameters either in the dams or their offspring. The ameliorative effect of vitamin E, based on estimating the "Ameliorative Index; AI" to malondialdehyde (MDA) and superoxide dismutase (SOD) ranged between 0.95 and 1.06 (≈1.0) for the dams and the pups either in gestational or lactational exposure routes. In general, the mouse pups were more vulnerable to ATZ toxicity than their mothers and exposure during gestation was suggested to be more effective than during lactation. The findings may support the need to further investigating the adverse effects of exposure to low doses of commonly used pesticides, especially during pregnancy and breast-feeding as well as effects on newborn child.

Adverse effects of exposure to low doses of chlorpyrifos in lactating rats.

This study was conducted to shed light on the effect of exposure of lactating rat to chlorpyrifos (CPF). CPF was orally administered to lactating rats at 0.01 mg kg(-1) b.wt. (acceptable daily intake, ADI), 1.00 mg kg(-1) b.wt. (no observed adverse effects level, NOAEL) and 1.35 mg kg(-1) b.wt. (1/100 LD( 50)) from postnatal day 1 (PN1) until day 20 (PN20) after delivery. Results indicated decreases in body weight and increases in relative liver and kidney weights of exposed dams. Significant damage to liver was observed via increased plasma levels of aminotransferases (aspartate aminotransferase (AST) and alanine aminotransferase (ALT)) lactate dehydrogenase (LDH) and γ-glutamyle transferase (γ-GT) in a dose-dependent manner. At two high doses of CPF (1.00 and 1.35 mg kg(-1) b.wt.), the lactating mothers showed significant decrease in the activity of cholinesterase (ChE). Lipid peroxidation was significantly increased, while glutathione s-transferase (GST) and superoxide dismutase (SOD) were significantly decreased compared to control. At high dose of CPF (1.35 mg kg(-1) b.wt.), total protein and uric acid levels were significantly increased. CPF caused dose-related histopathological changes in liver and kidney of the CPF-treated dams.

Risk assessment of pesticides and heavy metals contaminants in vegetables: a novel bioassay method using Daphnia magna Straus.

Cucumber and potato samples of known levels of pesticides and heavy metal residues, as respectively measured by gas chromatography and atomic absorption, were subjected to a bioassay method using Daphnia magna in order to assess the potential of the toxic hazard of their contaminants. Based on the estimated lethal time for 50% mortality (LT50) in daphnids, we suggested a classification to categorize toxic hazards in six definite ratings. Either samples of cucumbers (from conventional, greenhouse and organic farming) or potatoes (from conventional and organic farming) were evaluated for toxic hazard of the mixtures of pesticide residues and heavy metals, as well as mixtures of both. Accordingly, a 53.7% of cucumber samples were ranked as "Highly Toxic: HT"; a 18.5% "Moderately Toxic: MT); a 9.3% "Slightly Toxic: ST"; and a 18.5% "Practically Non-Toxic: NT". For potato samples, the ranking pattern to different classes was: Extremely Toxic: ET (LT50=<1h) for 11.1%; Very Toxic: VT (LT50=1-<3h) for 50.0%; HT (LT50=3-<12h) for 13.9%; MT (LT50=12-<24h) for 11.1%; ST (LT50=24-48 h) for 0.0%; and NT (LT50= >48 h) for 13.9% of the samples bioassayed.

Effects of methomyl on lipid peroxidation and antioxidant enzymes in rat erythrocytes: in vitro studies.

Erythrocytes are a convenient model to understand the membrane oxidative damage induced by various xenobiotic pro-oxidants. This study was designed to investigate the possibility of methomyl (Lannate 90% SP), S-methyl N-(methylcarbamoyloxy) thioacetimidate, to induce oxidative stress response in rat erythrocytes in vitro. Erythrocytes were incubated for 4 hours at 37 degrees C with different concentrations (0.0, 0.1, 0.5, 1.0, 1.5 and 2.0 mM) of methomyl. The results showed that methomyl decreased acetylcholinesterase (AChE), superoxide dismutase (SOD) and glutathione S-transferase (GST) activities and increased level of lipid peroxidation (LPO) as well as the percentage of haemolysis. The response occurred in a concentration-dependent manner. The study suggested that methomyl has the capability to induce oxidative damage as evidenced by increasing LPO and perturbations in various antioxidant enzymes.

Persistent organic pollutants (POPs) in Africa: Egyptian scenario.

Persistent organic pollutants (POPs) are organic (carbon-based) compounds that include synthesized substances (pesticides and polychlorinated biphenyls [PCBs]) and other by-product substances generated as a result of human and natural activity (dioxins and furans). Extensive scientific studies have shown that POPs are some of the most dangerous pollutants released into the environment by humans. Great efforts have been made since the early 1960s to enhance chemical management and safety issues. Various conventions have been adopted for this purpose: the Stockholm Convention (SC) is one of the well-known meetings in this context. The SC on POPs (May 2001) focuses on reducing and eliminating releases of 12 POPs coined the 'Dirty Dozen' by the United Nations Environment Program (UNEP). Persistence of such chemicals in soils, air, and water, together with natural processes such as evaporation to the atmosphere and washout by rain and flood, give rise to their ubiquitous distribution in the environment and eventual penetration into food chains and bio-accumulation in humans. Public concern about contamination by POPs increased recently because several of these compounds are identified as hormone disruptors, which can alter normal function of endocrine and reproductive systems in humans and wildlife. African countries are using pesticides, such as dichlorodiphenyltrichloroethane (DDT), lindane, toxaphene, endrin, dieldrin, heptachlor, since more than 50 years for combating agricultural pests and controlling disease vectors, especially malaria. The way in which pesticides are used in Africa caused serious environmental and health problems much more than elsewhere. These problems are represented by accumulation of organochlorine pesticide (OCP) residues in different environmental samples and hosting of at least 50,000 tons of obsolete pesticides, as well as tens of thousands of tons of contaminated soil. Within the framework of the Africa Stockpiles Program (ASP), huge quantities of pesticidal POPs have been completely or partially destroyed in a number of African countries (e.g. Egypt, Namibia, Niger, Senegal, Seychelles, South Africa, Sudan, Tanzania, Uganda, Zambia). At regional level (i.e. African Countries), a strategic plan for monitoring and getting rid of POPs in the continent should be set up and implemented through coordination between all governments. Among issues of top priorities are to find alternative non-combustion technologies for disposing obsolete pesticides, and to use alternative control measures for mosquitoes' management and other vector-borne diseases.

Monitoring of pesticides and heavy metals in cucumber fruits produced from different farming systems.

A total of 216kg of cucumber samples, representing three different types of farming production [e.g., conventional (C), greenhouse (G) and organic (O)], were collected from different locations in Giza governorate (Egypt), and subjected to pesticide residue and heavy metal analyses. Residues of some organochlorine pesticides (OCPs), such as hexachlorobenzene (HCB), heptachlor, aldrin, endrin, dieldrin and o,p'-DDT, as well as organophosphorus pesticides (OPPs), such as chlorpyrifos-methyl, thiometon and phorate were found in a number of samples at concentrations exceeding their MRLs. Lindane was detected in 33.3%, 50.0% and 25.0% of samples from C, G and O cucumber, respectively, without violation. The insecticide methamidophos showed high frequency in the analyzed samples of C, G and O cucumber accounting to 66.7%, 41.7% and 50.0%, respectively, without violation. The majority of the analyzed samples contained detectable concentrations of Zn, Cu, Mn, Fe, Cd, Pb, Cr, Ni and Co. Only, Pb and Cd were found in a number of samples at concentrations exceeding their MLs. Contamination among the three types of cucumber either by pesticides or heavy metals varied from a season to another. Generally, the greenhouse cucumber contained the highest value of total pesticide residues (1.016mgkg(-1)), followed by organic (0.442mgkg(-1)) and then conventional (0.415mgkg(-1)) cucumbers. Heavy metal contamination in the three cucumber types accounted to 4.968, 5.350 and 6.248mgkg(-1), respectively. The study shed light to the problem of multi toxicants in a food commodity such as cucumber; a common element in the daily human diet.

Evaluation of some pollutant levels in conventionally and organically farmed potato tubers and their risks to human health.

A total of 144 kg of potato tuber samples, representing two different types of farming production [e.g., conventional (C) and organic (O)], were collected from different locations in Giza governorate (Egypt), and subjected to pesticide residue and heavy metal analyses. Residues of some organochlorine pesticides (OCPs), such as HCB and heptachlor as well as some organophosphorus pesticides (OPPs), such as methamidophos, thiometon, profenofos, phorate and pirimiphos-methyl were found in a number of samples at concentration levels exceeding their MRLs. The majority of the analyzed samples contained detectable concentrations of Zn, Cu, Mn, Fe, Cd, Pb, Cr, Ni and Co. Specifically, Pb and Fe were found in a number of samples at concentrations exceeding their MLs. Contamination among the two types of potatoes varied from a season to another and contamination of C potatoes was nearly 2 times that of O potatoes either by pesticides or heavy metals. Estimation of dietary intake of pesticides and heavy metals by potatoes revealed that only phorate residues either in conventional or organic potatoes may pose risks to human health. None of the studied heavy metals showed to cause dietary intake risks to human health. The study shed light to the problem of multi toxicants in potatoes.

Environmental impact of pesticides in Egypt.

The first use of petroleum-derived pesticides in Egyptian agriculture was initiated in 1950. Early applications consisted of distributing insecticidal dusts containing DDT/BHC/S onto cotton fields. This practice was followed by use of toxaphene until 1961. Carbamates, organophosphates, and synthetic pyrethroids were subsequently used, mainly for applications to cotton. In addition to the use of about 1 million metric tons (t) of pesticides in the agricultural sector over a 50-yr period, specific health and environmental problems are documented in this review. Major problems represented and discussed in this review are human poisoning, incidental toxicity to farm animals, insect pest resistance, destruction of beneficial parasites and predators, contamination of food by pesticide residues, and pollution of environmental ecosystems. Several reports reveal that chlorinated hydrocarbon pesticide residues are still detectable in several environmental compartments; however, these residues are in decline. Since 1990, there is a growing movement toward reduced consumption of traditional pesticides and a tendency to expand use of biopesticides, including "Bt," and plant incorporated protectants (PIPs). On the other hand, DDT and lindane were used for indoor and hygienic purposes as early as 1952. Presently, indoor use of pesticides for pest control is widespread in Egypt. Accurate information concerning the types and amounts of Egyptian household pesticide use, or numbers of poisoning or contamination incidents, is unavailable. Generally, use of indoor pesticides is inadequately managed. The results of a survey of Egyptian farmers' attitudes toward pesticides and their behavior in using them garnered new insights as to how pesticides should be better controlled and regulated in Egypt.

Pesticide exposure--Egyptian scene.

Pesticides have contributed to dramatic increases in crop yields and in the quantity and variety of the diet. Also, they have helped to limit the spread of certain diseases. But pesticides have harmful effects; they can cause injury to human health as well as to the environment. The range of these adverse health effects includes acute and persistent injury to the nervous system, lung damage, injury to the reproductive organs, dysfunction of the immune and endocrine systems, birth defects, and cancer. Problems associated with pesticide hazards to man and the environment are not confined to the developing countries. Developed nations have already suffered these problems, and still facing some problems in certain locations. For many reasons, the severity of pesticide hazards is much pronounced in Third World Countries. A number of long persistent organochlorines and highly toxic organophosphates, which have been banned or severely restricted, are still marketed and used in many developing countries. The misuse of pesticides by concerned individuals, in addition to lack of or weak national controlling plans are behind the outbreak of adverse effects in developing countries. Since about 25 years, the use of DDT and many other organochlorine pesticides in Egyptian agriculture has been banned. However, these long persistent compounds are still detectable in many different types of environmental samples (e.g., water, fish, sediment, vegetables, fruits, milk, foodstuffs, etc.). Large number of compounds known as "extremely hazardous", "highly hazardous", "probable human carcinogenic", and "possible human carcinogenic", are listed among the pesticides registered and recommended for use in Egypt during the season of 2001/2002. The present article deals with: trends and patterns of pesticide use, impact of pesticides on human health, factors contributing to pesticide risks, environmental impacts of pesticides, and bioaccumulation of pesticide residues in food; giving special concern to the situation in Egypt.