Dragica Brkic

Carbofuran in water: Subchronic toxicity to rats.

Carbofuran toxicity on rats was studied during subchronic exposure. Female and male rats were administered carbofuran in drinking water in concentrations of 25, 100 and 400ppm for a period of 90 days. Clinical symptoms, water consumption, body weight gain, organ weight, pathological and histopathological changes in the liver and kidneys were observed and biochemical and haematological examinations were carried out. The results obtained show that carbofuran administered to rats caused a significant decrease in water consumption as well as in brain, serum and erythrocyte cholinesterase activities. Statistically significant increases in relation to the control were found in the serum enzyme activities. The haematological data showed that carbofuran had no significant effect on Hb concentration and total RBC, but total WBC showed a significant statistical decrease. The histopathological changes in liver and kidneys were observed. However, cell regeneration in the liver and kidneys was found in all test groups.

Development of water based pesticide system

It is well known that emulsifiable concentrates (EC), besides good properties have problem with a high solvent content thus are not environmental friendly and can cause problems for users. The interest in developing oil-in-water emulsions (EW) instead emulsifiable concentrates is increasing due to toxicological problems with solvents. Oil-in-water emulsions can reduce phytotoxicity, ecotoxicity and dermal toxicity, have a higher flash point than EC and are safer in transport and storage; also EW are more compatible with water based SC formulations for blends of active ingredients. Plant protection often includes the use of some pyretroides as active ingredients, for example Cypermethrin, alone or combined with Chlorpyrifos. It is a very old product which is formulated as EC formulation. In this study oil-in-water emulsion (EW) was developed with the same active ingredients. The EW formulation was tested and the results show that it was stable and therefore could be used in plant protection.

Environmental exposure to organophosphorus nerve agents

Exposure to organophosphorus nerve agents, the most deadly chemical warfare agents, is possible in a variety of situations, such as destruction of chemical warfare agents, terrorist attacks, armed conflicts or accidents in research laboratories and storage facilities. Hundreds of thousands of tons of chemical munitions were disposed of at the sea in the post World War II period, with European, Russian, Japanese and US coasts being the most affected. Sulfur mustard, Lewisite and nerve agents appear to be the most frequently chemical warfare agents disposed of at the sea. Addressing the overall environmental risk, it has been one of the priorities of the world community since that time. Aside from confirming exposure to nerve agents in the alleged use for forensic purposes, the detection and identification of biological markers of exposure are also needed for the diagnosis and treatment of poisoning, in addition to occupational health monitoring for specific profiles of workers. When estimating detrimental effects of acute or potential chronic sub-lethal doses of organophosphorus nerve agents, released accidentally or intentionally into the environment, it is necessary to understand the wide spectra of physical, chemical and toxicological properties of these agents, and predict their ultimate fate in environmental systems.

Toxicity of clomazone and its formulations to zebrafish embryos (Danio rerio)

Herbicides are the most widely used group of pesticides but after reaching water bodies they are able to cause adverse effects on non-target organisms. Different formulations using the same active ingredient are frequently available, which raises the issue of potential influence of different formulation types on herbicide toxicity. The present study evaluated the toxicity and teratogenic effects of the active ingredient clomazone and its two formulations (Rampa® EC and GAT Cenit 36 CS, both containing 360g a.i./l of clomazone) on zebrafish embryos. The crucial difference between the two formulation types is the way of active substance release. This investigation is the first report on zebrafish embryotoxicity of both clomazone and its formulations. The technical active ingredient and formulations caused mortality and diverse teratogenic effects, showing different levels of toxicity. The LC50 values for the technical ingredient, Rampa® EC and GAT Cenit 36 CS were 61.4, 9.6 and 92.5mg a.i./l, respectively. Spontaneous movements in 22 hpf embryos decreased under exposure to both the technical ingredient and formulations. A significant number of underdeveloped embryos was detected after exposure to clomazone and Rampa® EC, while no underdevelopment was noted in embryos exposed to GAT Cenit 36 CS. Exposure to the technical ingredient and formulations led also to a series of morphological changes and interfered with the growth of zebrafish embryos. The EC50 based on detection of edemas, spine and tail tip deformations and gas bladder absence (120hpf) was 12.1, 10.1 and 24.1mg/l for technical clomazone, Rampa® EC and GAT Cenit 36 CS, while teratogenicity index (TI) based on LC50/EC50 ratio was 5.1, 1 and 3.8, respectively. The data in this study showed that the emulsifiable concentrate formulation (Rampa® EC) caused statistically significantly higher toxicity, and the aqueous capsule suspension (GAT Cenit 36 CS) lower toxicity than technical clomazone. It indicates that different formulations with the same active ingredient may have different environmental impacts, which is why risk assessment based only on active ingredient toxicity might not be sufficient in terms of preventing formulation effects on the environment.

Some arguments in favor of a Myriophyllum aquaticum growth inhibition test in a water–sediment system as an additional test in risk assessment of herbicides

The present study compares the practicability, reproducibility, power, and sensitivity of a Myriophyllum aquaticum growth inhibition test in a water-sediment system with the recently accepted Myriophyllum spicatum test in an equivalent testing system and the standard Lemna sp. test. Special consideration was given to endpoints based on M. aquaticum control plant growth and variability of relative growth rate and yield: shoot length, fresh weight, dry weight, and root weight. Sensitivity analysis was based on tests performed with 3,5-dichlorophenol, atrazine, isoproturon, trifluralin, 2,4-dichlorophenoloxyacetic acid, and dicamba. Growth rates for average M. aquaticum control plants were 0.119 d(-1) and 0.112 d(-1), with average estimated doubling time 6.33 d and 6.74 d for relative growth rate fresh weight and shoot length, respectively. Intrinsic variability of M. aquaticum endpoints was low: 12.9%, 12.5%, and 17.8% for relative growth rate shoot length, relative growth rate fresh weight and yield fresh weight, respectively. The power of the test was fairly high. When the most sensitive endpoints were used for comparison, the 2 Myriophyllum species were similarly sensitive, more sensitive (in the case of auxin simulators), or at least equally sensitive as Lemna minor to other tested herbicides. The M. aquaticum 10-d test with a 7-d exposure period in a water-sediment system has acceptable sensitivity and can provide repeatable, reliable, and reproducible results; therefore, it should not be disregarded as a good and representative additional test in environmental risk assessment.

Occupational and Environmental Aspects of Organophosphorus Compounds

Besides being a potential risk to humans and other living organisms, organophosphorus (OP) compounds also poses a risk to the environment. Production and placing pesticides on the market are under national and international legislative framework, although in many developing countries the regulation is still inadequate or not properly enforced. Occupational exposure to OPs includes any job which involves either direct or indirect contact with OP compounds, while public exposure to OPs may occur through contaminated food or from hand-to-mouth contact with contaminated surfaces, inhalation and dermal contact.

Hematological effects of herbicide Avalon® (bentazon+dicamba) in rats

Hematological effects of the herbicide Avalon (GAL-57), a mixture of bentazon and dicamba, were tested on rats. Avalon was administered by gavage at three and four dose levels (250, 500, 1000 and 1250 mg/kg weight/day) for 28 and 90 days. Hematological parameters, number of erythrocytes, leukocytes and platelets, hemoglobin concentration, hematocrit and erythrocyte indexes (MCV, MCH and MCHC) were monitored. The results showed that the herbicide Avalon caused decrease in the values of hemoglobin, hematocrit and erythrocyte indexes (both males and females). The changes (mostly) correlated with the doses administered and, in most cases, a lower susceptibility of females than males was observed. The herbicide GAL-57 had no adverse effect on the number of leukocytes, erythrocytes and thrombocytes (both sexes, all doses tested). The results showed that the herbicide Avalon causes weak anemia to the animals tested. Reversibility was apparent during the recovery period of 28 days.

Oil dispersion with abamectin as active ingredient.

Abamectin was developed as an insecticide, nematocide and acaricide for use on a variety of agricultural and horticultural crops. The products with this active ingredient can be found on the market mostly formulated as emulsifiable concentrate (EC). Usually producers recommend using the EC formulation of abamectin together with some kind of adjuvants (natural oils) to improve efficacy of the active ingredient. To overcome the efficacy problem we tried to formulate the active ingredient abamectin as oil dispersion (OD). Oil dispersion, preferably based on naturally derived oils could improve pesticide efficacy. This type of pesticide formulation contains oil instead of water as in classical suspension concentrate and typically has better retention and coverage. In the case of abamectin, in this investigation soybean oil was used with the mixture of different nonionic emulsifiers. Content of abamecetin in formulation was 1.8 %. The developed formulation was tested for few important parameters. The obtained physicochemical properties for the above mentioned formulation have shown that it is stable and could be used in plant protection.

Acute oral toxicity study of GAL-57 (bentazon+dicamba) herbicide in rats.

An acute oral toxicity study of the herbicide GAL-57 (Avalon), a mixture of bentazon and dicamba as active ingredients, was investigated on rats, using a new method that has been used in the past several years (2001). Clinical observations symptoms and mortality were performed for all animals in different time intervals after treatment, and gross necropsy was performed at the end of observation period. Clinical symptoms (decreased activity, prone position, abnormal limb position, decreased righting reflex, decreased grip and limb tone, decreased body and abdominal tone, dyspnoea) of marked degree were noted after administration of 2000 mg/kg, and animals were dead in the period of 30-60 minutes after the treatment. GAL-57 did not cause any clinical sings at single 300 mg/kg bw dose. The physical condition and behavior of animals (males and females) were normal, and it is not differ in reaction to the control. According to the methodology used in the present study, it could be concluded that the acute oral LD-50 value of the GAL-57 proved to be between 300 and 2000 mg/kg body weight in rats, and the product was ranked into Poison group III according to Serbian criteria, category 4 of the Global Harmonized Classification System, and Category III of the EPA classification.

Subacute and subchronic toxicity of Avalon(®) mixture (bentazone+dicamba) to rats.

Subacute and subchronic toxicity of the herbicide Avalon(®), a mixture of bentazone and dicamba, were tested on rats. Avalon(®) was administered at dose levels of 250, 500 and 1000mg/kg body weight/day for 28 and 90 days. Alanine aminotransferase (ALT), aspartate aminotransferase (AST) and alkaline phosphatase (ALP) activities were monitored together with biochemistry parameters. The results showed that the mixture caused increases in the activities of ALT, AST and ALP, elevated concentrations of sodium, albumin and albumin/globulin ratio in males. In females, ALT activity, cholesterol and phosphate levels were increased. The changes generally were dose related and, in most cases, females exhibited lower susceptibility than males. The effects of a mixture are, in the most cases, different from the effects of the individual substances. The effects of bentazone were not prevalent which would be expected taking the composition of the mixture into account.