On the toxicity of some pesticides for fish [Translation from: Izv.gos.nauchno-issled.Inst.ozern.rybn.Khoz. 121, 95-96, 1977]

In the piscicide laboratory of GosNIORKh over a series of years was carried out the ichthyological evaluation of different agricultural pesticides, used both in our country and abroad. In all more than 300 different chemical substances were tested. Here, it was established that around 10% of them possessed high ichthyotoxic properties. Experiments were conducted under laboratory conditions on aquarium fish in groups, and also on representatives of different species of lake ichthyofauna. The basic criterion of evaluation of toxicity was the death of experimental fish during 120 hours. This short paper summarises the findings of this reasearch and offers a table presenting acute toxicity of pesticides for fish.

The half-lives of biological activity of some pesticides in water

In the absence of analytical methods, the half-lives of biological activity of pesticides can be estimated by bioassays. To determine the half-lives of biological acivity of pesticides to fish, static bioassays were conducted in the laboratory with ten different formulations of pesticides using Labeo rohita as a bio-indicator. The half-lives of biological activity for ten different pesticides in soft water at pH 7.5 and 27°C, ranged from 4.6 days to 11.8 days. The half-life of biological activity of Sumithion 50% EC was only 4.6 days. In contrast, Dimecron 50% EC degraded very slowly and its half-life of biological activity on L. rohita was about 11.8 days. Sumithion 50% EC, Padan 50% SP, EPN 45% EC, Diazinon 40% EC and Diazinon 10 G degraded in less than five to seven days indicating that these pesticides are desirable for rice-fish culture. Contamination by pesticides with long-term residual toxicity in waters may eventually cause high levels of fish mortality.

Compliance Program report of findings: FY 79 pesticides and metals in Fish Program (7305.007)

Because fish bioaccumulate* certain chemicals, levels of chemical contaminants in their edible portion must be closely monitored. In recent years, FDA has conducted several surveys designed to determine the occurrence and levels of selected chemicals or groups of chemicals in fish. Previous fish surveillance programs included the Mercury in Wholesale Fish Survey (FY 71), the FY 73 and 74 Comprehensive Fish Surveys, the Canned Tuna Program (FY 75), the Kepone and Mirex Contamination Program (FY 77), and the FY 77 Mercury in Swordfish Program. In addition, recent Compliance Programs for Pesticides and Metals in Foods and Pesticides, Metals, and Industrial Chemicals in Animal Feed have specified coverage of fish and fish products. Because of previous findings and the sustained high level of fish imported into the United States, a separate compliance program dealing solely with chemical contaminants in fish was initiated by the FDA Bureau of Foods in FY 78. The program includes all domestic and imported fish coverage except that directed by the Bureau of Veterinary Medicine for animal feed components derived from fishery products. The earlier surveys indicated that "bottom feeder" species such as catfish generally had the highest levels of pesticides and polychlorinated biphenyls (PCBs). For this reason, coverage at these species has been emphasized. Similarly, tuna has received special attention because it is the most prevalent fish in the U.S. diet and because of potential problems with mercury. Halibut, swordfish, and snapper also were emphasized in the sampling because of potential problems with mercury levels determined in previous years. The findings in this program were used in detecting emerging problems in fish and directing FDA efforts to deal with them. Care must be exercised in drawing conclusions about trends from the data because this Compliance Program was not statistically designed. Sampling objectives and sources may vary from year to year; thus the results are not directly comparable.

Investigation of unusual mortalities of bottlenose dolphins along the mid-Texas coastal bay ecosystem during 1992

An investigation was conducted into the deaths of more than 220 bottlenose dolphins (Tursiops truncatus) that occurred within the coastal bay ecosystem of mid-Texas between January and May 1992. The high mortality rate was unusual in that it was limited to a relatively small geographical area, occurred primarily within an inshore bay system separated from the Gulf of Mexico by barrier islands, and coincided with deaths of other taxa including birds and fish. Factors examined to determine the potential causes of the dolphin mortalities included microbial pathogens, natural biotoxins, industrial pollutants, other environmental contaminants, and direct human interactions. Emphasis was placed on nonpoint source pesticide runoff from agricultural areas, which had resulted from record rainfall that occurred during the period of increased mortality. Analytical results from sediment, water, and biota indicated that biotoxins, trace metals, and industrial chemical contamination were not likely causative factors in this mortality event. Elevated concentrations of pesticides (atrazine and aldicarb) were detected in surface water samples from bays within the region, and bay salinities were reduced to <10 ppt from December 1991 through April 1992 due to record rainfall and freshwater runoff exceeding any levels since 1939. Prolonged exposure to low salinity could have played a significant role in the unusual mortalities because low salinity exposure may cause disruption of the permeability barrier in dolphin skin. The lack of established toxicity data for marine mammals, particularly dermal absorption and bioaccumulation, precludes accurate toxicological interpretation of results beyond a simple comparison to terrestrial mammalian models. Results clearly indicated that significant periods of agricultural runoff and accompanying low salinities co-occurred with the unusual mortality event in Texas, but no definitive cause of the mortalities was determined. (PDF file contains 25 pages.)

Study and investigation of the various reactions of Mazandaran Province shoreline against wind waves

Determining of beach states and study of manner sediment transmission in beach profile, involves the evaluating the actions of hydrodynamic forces dominated over the beaches, in this research through determining the beach states by the help of Hanson and short method, different reactions of Mazandaran’s shoreline against wind waves was studied and investigated. For this reason, First, the kind of hydrodynamic forces dominated over the beaches of this province was studied and beaches of the this province was distinguished as wave–dominated beaches, afterwards eight stations are chosen throughout the shoreline and the waves qualities and the sediments regarding to different depth was evaluated in these stations by using software and laboratory actions. In this way the parameter of dimensionless fall velocity each station was calculated and the beach states and their changes according to time was studied. Finally, the gained information is located in the software area of Arc GIS, and the waves dynamics and the way of erosion and accretion was evaluated in each station. In this research by study of air photographs during a thirty years period we found that was no remarkable changes at shoreline in western and central parts and each type of change depends upon the delta, while eastern part of coast at the location of breakwaters in neighbouring of Farahabad Station, accretion features is quiet evident. In the main results of this research, it became obvious that the beach state in the stations Neca, Farahabad, Larim, Naftchal, Mazandaran university, Babolsar, Noor is dissipative and the beach in Nashtarood station is in intermediate (ridge and runnel) state to the extend that in the dissipation beaches from east to west, the degree of dissipation of the beaches is decreased continuously.

Pesticide induced physiological and behavioural changes in an estuarine teleost Therapon jarbua (Forsk)

Static bioassays were conducted with pesticides like PP'-DDT, Dimethoate (Rogor) and Carbaryl (Sevin) to determine the median lethal concentrations (LC sub(50)) on an estuarine teleost Therapon jarbua (Forsk). The respiration rates of fishes exposed to pesticides, as well as those of controls were determined. Respiration abnormalities were noticed in treated fishes. The metabolic rates are generally higher in treated fishes than in the controls. The behaviour of fishes exposed to LC sub(25) (96h) concentrations of pesticides is discussed. Estuarine fishes appear to be more sensitive and susceptible to pesticides than fresh water fishes. The pesticides affect the locomotory and swimming behaviour of fishes. Loss in weight of fishes exposed to LC sub(50) (96 h) concentration of pesticides was also estimated. The present report gives a comprehensive account of the toxic nature of these pesticides to fishes.

Endosulfan: a hidden menace

A clean and healthy environment is paramount to human existence. While pesticide use has successfully sustained agricultural and food production in our lifetime as well as safeguarded human health by controlling insect pests, it has also caused many tragedies including population declines in our wildlife, fatalities in workers exposed to pesticides in its manufacture and use, and the increasing incidence of dreaded human illnesses such as cancer. A delicate balance should be achieved to mitigate the adverse impact of pesticide use to the environment and at the same time ensuring short- and long-term agricultural productivity. Endosulfan has been effectively used as a pesticide, but much evidence on its chronic and sub-lethal effects on humans and wildlife have been gathered in recent years. More research still needs to be done to determine its effects from long-term exposure at very low levels. Endosulfan is highly toxic to fish and other aquatic animals and, thus, not recommended for use in aquatic ecosystems. However, in some countries, it has been incorrectly used as a molluscicide in rice paddies, which could have an adverse impact on the rice-fish farming systems and on other surrounding aquatic ecosystems. It is clear that such practices should be stopped and users must strictly observe the recommended application methods. Agricultural productivity should be achieved with less pesticide by using integrated pest management programs which make use of biological, cultural, and physical control agents and lower doses of safer pesticide on a need only basis. The benefits of biotechnology should also be used to develop more effective and safer products and techniques. This is a valid approach and one that will require a unified and concerted effort among suppliers and users of pesticides in order to ensure that resources are used to our best advantage with minimal risk.

The effects of two pesticides on Clarias gariepinus

Bioassays were carried out to determine the toxicity of two pesticides, Roundup and Gramoxone on Clarias gariepinus. The acute toxicity of both pesticides decreased towards the end of the bioassay period. The calculated safe concentrations for Roundup and Gramoxone are 0.99 ppm - 0.99 ppm and 0.09 ppm - 0.9 ppm respectively. Histological examination revealed that there were pathological changes in the gills and liver even when the fish were subjected to sub-lethal levels

Concentrations of Polychlorinated Biphenyls (PCB’s), Chlorinated Pesticides, and Heavy Metals and Other Elements in Tissues of Belugas, Delphinapterus leucas, from Cook Inlet

Tissues from Cook Inlet beluga whales, Delphinapterus leucas, that were collected as part of the Alaska Marine Mammal Tissue Archival Project were analyzed for polychlorinated biphenyls (PCB’s), chlorinated pesticides, and heavy metals and other elements. Concentrations of total PCB’s (ΣPCB’s), total DDT (ΣDDT), chlordane compounds, hexachlorobenzene (HCB), dieldrin, mirex, toxaphene, and hexachlorocyclohexane (HCH) measured in Cook Inlet beluga blubber were compared with those reported for belugas from two Arctic Alaska locations (Point Hope and Point Lay), Greenland, Arctic Canada, and the highly contaminated stock from the St. Lawrence estuary in eastern Canada. The Arctic and Cook Inlet belugas had much lower concentrations (ΣPCB’s and ΣDDT were an order of magnitude lower) than those found in animals from the St. Lawrence estuary. The Cook Inlet belugas had the lowest concentrations of all (ΣPCB’s aver-aged 1.49 ± 0.70 and 0.79 ± 0.56 mg/kg wet mass, and ΣDDT averaged 1.35 ± 0.73 and 0.59 ± 0.45 mg/kg in males and females, respectively). Concentrations in the blubber of the Cook Inlet males were significantly lower than those found in the males of the Arctic Alaska belugas (ΣPCB’s and ΣDDT were about half). The lower levels in the Cook Inlet animals might be due to differences in contaminant sources, food web differences, or different age distributions among the animals sampled. Cook Inlet males had higher mean and median concentrations than did females, a result attributable to the transfer of these compounds from mother to calf during pregnancy and during lactation. Liver concentrations of cadmium and mercury were lower in the Cook Inlet belugas (most cadmium values were <1 mg/kg and mercury values were 0.704–11.42 mg/kg wet mass), but copper levels were significantly higher in the Cook Inlet animals (3.97–123.8 mg/kg wet mass) than in Arctic Alaska animals and similar to those reported for belugas from Hudson Bay. Although total mercury levels were the lowest in the Cook Inlet population, methylmercury concentrations were similar among all three groups of the Alaska animals examined (0.34–2.11 mg/kg wet mass). As has been reported for the Point Hope and Point Lay belugas, hepatic concentrations of silver were re