About fish toxicity

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What is fish toxicity?

The toxicity of chemical substances dissolved in water to fish is called “fish toxicity”.

It is also sometimes referred to as “harmful to the aquatic environment”.

 

 

 

Method of fish poison test and its use

Commonly used as fish for fish toxicity test are ” Japanese medaka” and “Carp”, but also “Bluegill”, “rainbow trout”, “guppy”, “zebrafish”, “fathead minnow”, etc. It can be used.

These fish are exposed to a chemical substance (test substance) dissolved in water for 96 hours, and the mortality rate is measured.

The method of measuring “LC50” is the same method.

The higher the mortality rate, the higher the fish toxicity.

 

What is exposure?

 

The dictionary says “to be exposed to bacteria, viruses, drugs, and so on.”

The term “exposure” used here is used because organisms live in water in which chemical substances are dissolved, and they are always “exposed” to chemical substances.

 

 

Hazard type

Aquatic environment acute hazard

Hazard caused to organisms in a short period of time when exposed to water

 

Chronic aquatic environmental hazard

When exposed to water, no hazard can be ascertained immediately, but a hazard that adversely affects living organisms after a period corresponding to the life cycle of aquatic organisms.

 

 

 

Fish toxicity of solvent

The fish toxicity of the solvent, if available, will be noted on the SDS (Material Safety Data Sheet).

In the SDS, what kind of fish was used and how much numerical result was obtained is described, and for those without data (not measured), it is described as “no information”.

 

 

Notation example

Acetone

Aquatic environment acute hazard: Fish, Fat LC50>100mg/L/96H

Chronic aquatic environmental hazard: Not sparingly water-soluble (water solubility 1.00×106mg/L)

 

Toluene

Acute toxicity to aquatic environment: Crustacean brown shrimp EC50 3.5mg/L/96H

Chronic aquatic environmental hazard: No information

 

Methanol

Acute toxicity to aquatic environment:

96 hours LC50 = 15400mg/L (EHC 196, 1998) on fish (bluegill),

96 hours LC50 = 1340mg/L in crustaceans (Brown Shrimp) (EHC 196, 1998)

Chronic aquatic environmental hazard:

Not poorly water-soluble (water solubility = 1.00×106mg/L (PHYSPROP Database, 2005))

 

* Sankyo Chemical Co., Ltd. SDS reference

 

 

 

What happens to the fish after the test?

After the test, two types remain, one that died due to fish toxicity and another that survived.

The response varies depending on the testing institute, but dead animals are removed and are memorialized at each death.

Surviving individuals may not be available for further testing as they may have already taken up exposed chemicals.

Therefore, it seems that people often euthanize after the test.

 

 

 

After all, when is the test to be conducted?

Chemicals, in particular, are sometimes used near rivers and the sea and can flow as wastewater.

It is necessary to conduct a test in advance because it will cause a problem if it affects aquatic organisms if it flows out or is discharged as wastewater.

The fish toxicity test is a test that should be conducted before commercializing chemical products used in the above locations.

 

 

Past fish toxicity incidents

Tianjin Binhai New Area warehouse explosion accident (August 2015, China)

In the Tianjin explosion accident that occurred in August 2015, a large amount of chemical substances in the port flowed into the river due to the explosion.

Mass fish deaths have been found in rivers 6 kilometers away from the site of the explosion.

Originally, it was said that the area where eutrophication proceeded due to the influence of the sluice gate, and a large number of fish often died in the summer when the temperature rises, but when we were concerned about the influence of chemical substances, we proceeded with the investigation and found that the sewage near the explosion occurred. Has detected up to 800 times the standard value of sodium cyanide.

Although the detailed cause has not been clarified, it may be considered as one of the cases of mass death due to the fish toxicity of chemical substances.

 

Mass death in the old Ayasegawa (November 2017, Japan)

In November 2017, a large number of fish died in the Koyase River in Soka City, Saitama Prefecture.

The river is emerald green with over 100 dead fish.

The cause was copper chloride from a nearby factory. The tank that was storing copper chloride was cracked and leaked.

For copper chloride SDS

Hazard to aquatic environment (acute): It was classified into Category 1 from 96 hours LC50 = 0.018mg/L of fish (rainbow trout) (ECETOC TR91, 2003).

Hazardous to the aquatic environment (long-term): Classified into Category 1 since its acute toxicity is Category 1 and its behavior in water and bioaccumulation is unknown as it is a metal compound.

It is written that it is fish toxic.

 

 

You can see again how important it is to check the safety data sheet before using the product.

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