Adverse Effects
Teflubenzuron
CAS No.
83121-18-0

 
 

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Activity: Insecticide (benzoylurea)
Structure:


Adverse Effects:
Liver
Lymph node haemangiomas
Pancreas
Environmental

Teflubenzuron is an acyl urea derivate classified as an insecticide for use in treatment of infestation with sea lice in salmon. Teflubenzuron is admixed with pelleted diet at a level of 2 g/kg. The intended dosage level of teflubenzuron is 10 mg/kg bw administered once daily for 7 consecutive days. The substance is also used as a pesticide on crops. Very few substances are available for treatment of sea lice in salmon...
January 1999 - Summary Report. Committee for Veterinary Medicinal Products. The European Agency for the Evaluation of Medicinal Products.
http://www.fluoridealert.org/pesticides/teflubenzuron.review.1999.pdf

There is very little information available on the environmental fate and ecological effects of teflubenzuron in aquatic environments. The specific mode of action of teflubenzuron means it is highly toxic to aquatic crustacean invertebrates, but low in toxicity to fish, mammals and birds. As with emamectin benzoate, it is likely that the sediments will act as a sink for teflubenzuron and so sediment associated organisms are more likely to be affected by this chemical...
Ref: Calicide (Teflubenzuron) - Authorisation for use as an in- feed sea lice treatment in marine cage salmon farms. Risk Assessment, EQS and Recommendations (As agreed at the Board Meeting held on 7 th July, 1998 and subsequently updated in July, 1999). Policy No. 29. SCOTTISH ENVIRONMENT PROTECTION AGENCY. Fish Farming Advisory Group.
http://www.fluorideaction.org/pesticides/teflubenzuron.scotlandepa99.pdf

TOXIC chemicals used on salmon farms could be killing off key elements of the marine food chain, according to a report leaked to a leading scientific magazine. ‘New Scientist’ magazine has obtained a copy of a 178-page report which forms part of the ongoing £4 million study into the industry, which was launched by the UK government in 1999. In the leaked document it is alleged that chemicals such as cypermethrin, azamethiphos or teflubenzuron are damaging small crustaceans and other marine wildlife, which could be crucial to the survival of other species. These chemicals are often used by farmers to rid fish of sea lice.
See also April 25, 2002 press release from Friends of the Earth, Scotland.
Ref:
Leaked Report Claims Toxins Are Hitting Marine Food Chain Fish Farming Today- Fish Farming Today. April 25, 2002


Liver (click on for all fluorinated pesticides)

-- Short term repeat dose toxiciity tests in rats, mice and dogs revealed that the major target organ for the toxic effect of teflubenzuron is the liver. The main findings attributed to hepatoxiciity were increased liver weights and liver lesions, such as hepatocellular swellings, collapsed stroma, fatty changes, necrosis and cell infilitration.
-- In a 18-month carcinogenicity study in mice, teflubenzuron was given via the diet at concentrations of 0, 15, 75 or 375 mg/kg feed, equal to 0, 2.1, 10.5 or 53.6 mg/kg bw/day in males and 0, 3.1, 15.4 or 71.7 mg/kg bw/day in females... Non-neoplastic dose-dependent hepatic changes were observed in both sexes of all treated groups, such as hypertrophy, hyperplasia, single cell necrosis, phagocytic cell foci, lipofuscin accumulation and glycogen storage. The incidence of hepatocellular adenomas at 18 months (terminal kill) was significantly increased in males at the two highest dose groups: 22% in the mid-dose group and 32% in the high dose group versus 12% in the concurrent control group and 16% in the historical control group. There were no changes in the incidence of hepatocellular carcinomas. Since the increased incidence of hepatocellular adenomas is likely to be secondary to the hepatoxicity of teflubenzuron and was of a type generally not considered to be of concern for human health if not accompanied by other evidence for carcinogenicity, the mouse study was considered not to provide evidence for carcinogenicity of teflubenzuron.
-- The FAO/WHO Joint Meeting on Pesticides Residues (JMPR) evaluated teflubenzuron in 1994 and established an ADI of 0.01 mg/kg bw/day, based on the dose-related effects in the target tissue liver in the mouse carcinogenicity study submitted.
January 1999 - Summary Report. Committee for Veterinary Medicinal Products. The European Agency for the Evaluation of Medicinal Products.

http://www.fluoridealert.org/pesticides/teflubenzuron.review.1999.pdf

Lymph node haemangiomas (click on for all fluorinated pesticides)

-- In a 120-week long-term toxicity/carcinogenicity study, rats were fed diets containing 0, 20, 100 or 500 mg/kg feed, equal to 0, 1, 4.8 or 24.8 mg/kg bw/day in males and 0, 1.2, 5.9 and 29.9 mg/kg bw/day in females... Histopathological examination indicated an increased incidence of mesenteric lymph node haemangiomas in males in the high dose group (17%) in comparison with rats in concurrent controls (2%), but not when compared to the incidence in historical controls. A significantly increased incidence of pancreatic exocine carcinomas in male rats in the high dose group (4.3%), compared to concurrent controls (0 out of 50) and historical control groups (1.4% or 1 out of 69), was based on a low number of affected rats (2 out of 47) and was therefore not considered to be treatment related.
January 1999 - Summary Report. Committee for Veterinary Medicinal Products. The European Agency for the Evaluation of Medicinal Products.

http://www.fluoridealert.org/pesticides/teflubenzuron.review.1999.pdf

Pancreas (click on for all fluorinated pesticides)

-- In a 120-week long-term toxicity/carcinogenicity study, rats were fed diets containing 0, 20, 100 or 500 mg/kg feed, equal to 0, 1, 4.8 or 24.8 mg/kg bw/day in males and 0, 1.2, 5.9 and 29.9 mg/kg bw/day in females... Histopathological examination indicated an increased incidence of mesenteric lymph node haemangiomas in males in the high dose group (17%) in comparison with rats in concurrent controls (2%), but not when compared to the incidence in historical controls. A significantly increased incidence of pancreatic exocine carcinomas in male rats in the high dose group (4.3%), compared to concurrent controls (0 out of 50) and historical control groups (1.4% or 1 out of 69), was based on a low number of affected rats (2 out of 47) and was therefore not considered to be treatment related.
Ref: January 1999 - Summary Report. Committee for Veterinary Medicinal Products. The European Agency for the Evaluation of Medicinal Products.
http://www.fluoridealert.org/pesticides/teflubenzuron.review.1999.pdf

Environmental (click on for all fluorinated pesticides)

TOXIC chemicals used on salmon farms could be killing off key elements of the marine food chain, according to a report leaked to a leading scientific magazine. ‘New Scientist’ magazine has obtained a copy of a 178-page report which forms part of the ongoing £4 million study into the industry, which was launched by the UK government in 1999. In the leaked document it is alleged that chemicals such as cypermethrin, azamethiphos or teflubenzuron are damaging small crustaceans and other marine wildlife, which could be crucial to the survival of other species. These chemicals are often used by farmers to rid fish of sea lice.
- See also April 25, 2002 press release from Friends of the Earth, Scotland.
Ref:
Leaked Report Claims Toxins Are Hitting Marine Food Chain Fish Farming Today- Fish Farming Today. April 25, 2002

-- There is very little information available on the environmental fate and ecological effects of teflubenzuron in aquatic environments. The specific mode of action of teflubenzuron means it is highly toxic to aquatic crustacean invertebrates, but low in toxicity to fish, mammals and birds. As with emamectin benzoate, it is likely that the sediments will act as a sink for teflubenzuron and so sediment associated organisms are more likely to be affected by this chemical.
--
It is difficult to predict the ecological risk of teflubenzuron to the marine environment because of the current lack of information. Results from field studies referred to in SEPA’s environmental risk assessment suggest that the use of teflubenzuron for sea lice control may present a moderate to high environmental risk. It seems unlikely that teflubenzuron will be widely used for sea lice control in Scotland, but if use does increase, investigation into the potential long-term impacts of this chemical on the marine environment is recommended.
Ref: REVIEW AND SYNTHESIS OF THE ENVIRONMENTAL IMPACTS OF AQUACULTURE. The Scottish Association for Marine Science and Napier University. Scottish Executive Central Research Unit. 2002.
http://www.scotland.gov.uk/cru/kd01/green/reia.pdf

Although teflubenzuron is relatively non-toxic to most marine species (e.g. fish, algae, shellfish), it is potentially highly toxic to any species which undergo moulting within their life cycle. This will therefore include some commercially important marine animals such as lobster, crab, shrimp and some zooplankton species.
Subsequent chemical analysis confirmed that measurable concentrations were generally not present in water after treatment and that levels in sediments were variable but followed the predicted dispersion model with measured levels of teflubenzuron extending initially to about 50m from cages in line with the main direction of current. In the study, teflubenzuron was found to persist longer than 6 months, which was longer than expected and hence additional studies were commissioned by Nutreco at the request of SEPA and VMD. The predicted half-life of teflubenzuron in sediment was from 8 to 92 days depending on sediment type (Myrvold, 1997) and it had been expected that 90% of teflubenzuron should have been degraded within 6 months. The indication of a potential for longer persistence is attributed to the site being a ieworst casels site already enriched and impacted by organic wastes with teflubenzuron being retained by binding with organic material (Trouw, 1999). The results from long-term site monitoring finally reported a half life of 104 to 123 days (Trouw, 1999). From this data, SEPA now intend to apply a half life of 115 days as a decay factor when undertaking site loading calculations for consent applications or reviews.
Chemical analysis of samples collected on-site of indigenous crustacea was also undertaken. It was concluded that there was a risk that sediment dwelling crustacea, such as edible crab (Cancer) and possibly Norwegian lobster (Nephrops), may accumulate teflubenzuron from contaminated sediment. However, it is known that depuration and loss of teflubenzuron does proceed following initial exposure and uptake (McHenery, 1997) and hence levels may be lost from such species before toxic effects occur (moulting).
The half-life of teflubenzuron in sediment suggests that there is a moderate risk of build up in sediment through repeat applications, although the risk of this is reduced where fewer applications are required by correct use of the product strategy.
Ref: Calicide (Teflubenzuron) - Authorisation for use as an in- feed sea lice treatment in marine cage salmon farms. Risk Assessment, EQS and Recommendations (As agreed at the Board Meeting held on 7 th July, 1998 and subsequently updated in July, 1999). Policy No. 29. SCOTTISH ENVIRONMENT PROTECTION AGENCY. Fish Farming Advisory Group.
http://www.fluorideaction.org/pesticides/teflubenzuron.scotlandepa99.pdf

 

 
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