ACUTE TOXICITY OF CARBAMATE-BASED PESTICIDES FOR FISH

Hejduk I., Z. Svobodova: Acute Toxicity of Carbamate-based Pesticides for Fish. Acta vet. Brno, 49, 1980: 251257 . Ichthyotoxicological examination of carbamate-based pesticides was made according to the norm CSN 466807 "Test of Acute Toxicity for Fish". The following compounds were tested: Novozir MN 80, Elocron WP 50, Furadan 5-G and Fundazol. On the basis of the determined LC so values all compounds have been included among substances highly toxic for fish in the following order: Furadan G-5 > > Novozir MN 80 > Blocron WP 50 > Fundazol. The most susceptible fish species was found to be the rainbow trout followed by Poecilia reticulata and carp. The clinical signs and pathoanatomicallesions of the intoxication with carbamatebased pesticides in fish were not specific. Acute toxicity, LCso, Cyprinus carpio L., Salmo gairdneri Rich., Poecilia reticulata. The increasing chemization in all areas of man's activities has besides its benefits also a negative impact. At present, all newly introduced chemical compounds must be evaluated and tested for all possible effects.This pertains particularly to pesticides whose testing must include also-the ichthyopathological examination in areas of their use as indicated by the protocols gathered at the Fisheries Research Institute in Vodiiany showing high incidence of fish intoxications by pesticides (S v0bodova and Kocova 1973). The present work is focused at the carbamate-based pesticides which are being increasingly employed as herbicides, fungicides, insecticides and acaricides. Materials and Methods The following carbamate-based pesticides were examined for their toxicity for fish: Novozir MN 80, Blocron WP 50, Furadan G-5 and Fundazol. The acute toxicity of these compounds. was determined according to the CSN 46 6807 "Test of Acute Toxicity for Fish". Data on the tested pesticides were obtained from the list of permitted preparations for plant protection. The experimental fish were in good state of health. During the preliminary trial the clinical and pathoanatomical signs of intoxication were observed. Novozir MN 80 is a yellow-brown pulver a characteristic odour. In water it forms a very good suspension. The active substance is 80 % mancozeb (zinc manganate etylen-bis-dithiocarbamidan). For the toxicity test, carp (Cyprinus carpio L.) weighing 5.78 g (5.4-6.5 g), with body length of 5.38 em (4.2 7.3 em) and average Fulton's coefficient of 2.96 (2.55 3.91) were used. Further, rainbow trout (Salmo gairdneri Rich.) fry weighing 2.88 (1.4-4.8 g), with average body length of 5.74 em (4.6-7.3 em) and Fulton's coefficient of 1.49 (1.13-1.74) and specimens of Poecilia reticulata 2.19 em (1.73.0 em) long and not older than 6 months were used.


Materials and Methods
The following carbamate-based pesticides were examined for their toxicity for fish: Novozir MN 80, Blocron WP 50, Furadan G-5 and Fundazol.The acute toxicity of these compounds.was determined according to the CSN 46 6807 "Test of Acute Toxicity for Fish".Data on the tested pesticides were obtained from the list of permitted preparations for plant protection.The experimental fish were in good state of health.During the preliminary trial the clinical and pathoanatomical signs of intoxication were observed.
For testing, carp weighing 7.74 g (5.2-10.5 g) and 6.15 em long (5.6-6.8 em), with Fulton's coefficient averaging 3.27 (2.86 -3.62).The rainbow trout were weighing 2.87 g (1.9-5.7 g), they were 5.76 cm long (4.0-7.7 em) and their Fulton's coefficient averaged 1.37 (1.08-1.55).The Poecilia reticulata specimens were 2.77 em (2.2 -3.4 em) long and aged up to 6 months.N ovozi r MN 80 Toxicity for fish: In the 48-hour interval, the LCi)o of Novozir MN 80 was 24.0 mg.1-1 for the carp, 1.85 mg.l-1 for the rainbow trout, and 2.2 mg.1-1 for Poecilia reticulata..The minimum lethal concentration (LC a) was 15 mg.1-1 for the carp, 1.0 mg.I-I for the rainbow trout and 0.9 mg.1-1 for Poecilia reticulata in the same interval.From the time course of lethal intoxication with Novozir MN 80, given in Fig. I, high toxicity for fish is obvious.Clinical findings: In all fish species exposed to the toxic substance restless movements in the upper half of the aquarium were observed.Increased respiration, occasionally even convulsions of the mouth and opercles were noted.After this relatively long period first signs of lost balance occurred, later progressive increase of uncoordinated movements was evident with turning along the body axis.Before death, excitation with jumping above the water surface and swimming on one side was observed.Pathoanatomical findings: The body surface of affectedfish was polluted with the preparation.Skin slightly more mucous and pale.Eyes unchanged.The gills with smooth margins and increased mucous discharge, polluted with the preparation in fish exposed to its high concentrations.The lower parts of the gills were slightly more mucous.In the body cavity injected hepatic and hepatopancreatic blood vessels were found.

Results
Elocron WP 50 Toxicity for fish: The LC 50 of this compound was 25.5 mg.1-1 for the carp, 2.7 mg.1-1 for the rainbow trout, and 36.0 mg.1-1 for Poecilia reticulata in 48 hours.The minimum lethal concentration (LC s ) was found to be 17.5 mg.1-1 for the carp, 0.35 mg.lr-' for the rainbow trout and 16.0 mg.Ir-' for Poecilia reticulata in the same interval.The relation between the average survival time and the concentration of Elocron WP 50 is given in Fig. 2. The preparation is highly toxic for fish.Clinical findis: Extremely rapid course of intoxication is typical of Elocron WP 50.Upon exposure to high concentration, immediately loss of equilibrium occurred, followed by motor incoordination and movements in the upper part of the aquarium.Later recumbent or vertical position with head downards, occasional jumping above the water surface occurred.The most vigorous excitation was seen in the rainbow trout.In coma, the fish were lying on the bottom of the vessel with mouth and opercles wide-open and typical arch-like bending of the spine.In Poecilia reticulata invariably intensive colour of the body surface was noted.At lower concentrations of the toxic substance restlessness followed by loss of equilibrium occurred.All fish showed high excitability.Pathoanatomical findings: Body surface of intoxicated fish was slightly more mucous.In the carp no changes in skin colour were seen, in the rainbow trout more intensive colours occurred except for the area of the breast fins being very pale.Single haemorrhagiae were found in the eyes.Slightly more mucus was also found on the gills and on the lower part of the opercles.The gills had-smooth edges and normal colour.Injected blood vessels of hepatopancreas and liver were noted.Furadan G-5 Toxicity for fish: The LC 50 was 11.0 mg.1-1 for the carp, 8.5 mg.Ir-' for the rainbow trout and 3.4 mg.1-1 for Poecilia reticulata in 48 hours.The minimum lethal concentration (LC 5 ) was 5.8 mg.1-1 for the carp, 2.9 mg.1-1 for the trout and 2.0mg.1-1 for Poecilia reticulata (see Fig. 3).According to the LC:jo values Furadan G-5 should be included among compounds highly toxic for fish.
Clinical findings: In exposed fish increasing restlessness, vigorous swimming to the water surface and jumping, loss of equilibrium, incoordinated movements followed by abnormal postures and swimming on one side, coma and death.
In the period between the loss of equilibrium and death no excitations were observed except for the rainbow trout showing numerous excitations.In Poecilia reticulata stretched operculums and arch-like bending of the spine was observed in coma and death.The course of poisoning was extremely rapid in all three fish species.The gills had smooth rims, and they were more mucous, of usual colour in the carp, congested in the trout.Haemorrhagiae were found in the eyes of the carp.
Injected blood vessels of the liver and hepatopancreas were found.

Fundazol
Toxicity for fish: The LC so of Fundazol was 190 mg.1-1 for the carp, 1.8mg.l-1for the trout and 110 mg.l-1 for Poecilia reticulata in 72 hours.The minimum lethal concentration (LC s ) was 76 mg.l-1 for the carp, 0.49 mg.1-1 for the rainbow trout and 65 mg.1-1 for Poecilia reticulata.The course of poisoning may be seen from Fig. 4. According to the present results, Fundazol should be included among compounds highly toxic for fish.Clinical findings: The poisoning was not as rapid as with other substances.under study and the test was prolonged to 72 hours.Intoxication started with.mild restlessness increasing with time.Later loss of equilibrium, motor incoor-dination, coma and death followed.In the entire course of poisoning depression.prevailed in all fish.Pathoanatomical findings: In necropsied carp and trout the skin was found.to be more mucous; the skin was polluted and the gills slightly more mucous and.also contaminated in fish exposed to higher concentrations of the compound.
Their colour was unchanged in the carp but pale in the trout.Small haemorrhagiae were found in the eyes of the carp along with injected blood vessels of their hepatopancreas.

Discussion
The acute toxicity tests revealed the following order of toxicity for fish of the' carbamate-based pesticides: Furadan G-5 > Novozir MN 80 > Elocron WP 50 > Fundazol.All these compounds have been included among preparations highly toxic for fish on the basis of their LC s1 values in 48 hours (72 hours for Fundazol).The LC 50 values for Furadan G-5 and Novozir MN 80 were up to 10 mg.1-1 for the rainbow trout and Poecilia reticulata, and 10-100 mg.l-1 for the carp.Both preparations can be characterized as highly toxic for the two above-mentioned fish species, and toxic for the carp.Elocron WP 50 is highly poisonous for the rainbow trout and toxic for the carp and Poecilia reticulata.
Fundazol was found to be highly toxic for the rainbow trout and moderately poisonous for the two remaining, species having the LC oo above 100 mg.1-1 (Table 1).Toxicity of pesticides based on various forms of carbamates for fish varies widely as indicated by earlier data (Will iam s et a1. 1973;Sv0 bod 0 va and Fuka 1974;Wasserschadstoff-Katalog 1975) and by present results.It is likely' that the anticholinesterase activity of various carbamates differs as is the case with the organic phosphorous compounds (S eve I k 1968; Rie dI and Von d r acek 1971).However, besides the concentration of the toxic compounds, also the.possible poisonous effects of the secondary components (adjuvants, solvents) should be considered (Vejvoda 1966;Svob o dova 1971;Kvasnicka and Svobo dova 1977).
The reported acute toxicity test showed the carbamate-based pesticides to be most toxic for the rainbow trout followed by Poecilia reticulata and the carp (Table 1).The widest differences in LC ao between the fish species under study were found for Fundazol being 60-100 times lower for the trout than for the carp and Poecilia reticulata.This difference can partly be ascribed to the fact that Fundazol with low solubility attached to the skin surface and gills of the fish so that besides its toxic effects it also interfered with the physiological function of the gills.This effect made itself felt especially in the rainbow trout, the species most vulnerable to oxygen defficiency as compared to the other two species.
The clinical findings in fish intoxicated with carbamate-based pesticides were similar for all tested preparations.Intoxication was characterized by increasing restlessness, rapid respiration, loss of equilibrium, motor incoordination, swimming on one side, coma and death.In fish poisoned with Furadan G-5 and Fundazol depression predominated.The course of poisoning was extremely rapid with Elocron WP 50 and Furadan G-5.The pathoanatomical findings showed no characteristic features.
It can be concluded that the clinical and pathoanatomicalfindings in fish intoxicated with carbamate-based pesticides do not provide typical symptoms serving for unequivocal diagnosis of the poisoning.