Organochlorines

Question 1

What is a pesticide?

Answer 1

Substances meant to seduce and destroy pests

Can be chemicals or other substances

Question 2

What are the two major statutes that regulate pesticide use in the US?

Answer 2

FIFRA: Federal insecticide, fungicide, and rodenticide act

FFDCA: Federal food, drug, and cosmetic act

Question 3

What are sources of organochlorines?

Answer 3

Naturally through biological, physical, and chemical processes

includes: bacteria, fungi, plants, marine organisms etc

Question 4

T/F: Organochlorines are persistent in the environment

Answer 4

TRUE

chlorination of organic compounds reduces reactivity which will increase stability in the environment

Question 5

T/F: Organochlorines are water soluble

Answer 5

FALSE

They are lipophilic and have a reduced solubility in water

Question 6

What generation organochlorines are used as pesticides?

Answer 6

Second generation - synthetic compounds

*first generation are highly toxic and have been discontinued (arsenic/cyanide)

Question 7

What are the two main groups of organochlorines?

Answer 7

1. DDT type (banned)
2. Chlorinated alicyclics

These are neurotoxicants with different MoA

Question 8

What are the effects of DDT organochlorine bioaccumulation?

Answer 8

These compounds have long half-lives, up to 15 years - this gives small organisms a lot of time to take up and accumulate DDT in the fatty tissue, which can lead to toxic levels and death

Question 9

What is biomagnification?

Answer 9

Takes place when organisms higher in the food chain eat the smaller organisms lower in the food chain such that the environmental chemical is biomagnified (higher contaminant levels)

Question 10

What biomagnification effect did DDT have on the environment?

Answer 10

Caused a major decline in the population of the bald eagle and other bird of prey due to DDTs estrogen like activity –> decreased calcium in egg shells, making them weak –> poor survival

Question 11

T/F: Organochlorines are banned in the US, so there is no chance of exposure

Answer 11

FALSE

although they are banned - there is still potential for exposure since they are used in other countries and can be illegally imported

Question 12

In what situations will animal be exposed to toxic levels of organochlorides?

Answer 12

• when the label directions are not followed
• miscalculation of concentrations for spraying or dipping
• contaminated sources of feed or water
• unsecured or unlabeled packages or containers
• lack of PPE

Question 13

What is the primary route of organochlorine absorption?

Answer 13

• Dermal - (most common) - damaged skin allows absorption
• GI - absorption is enhanced by fat or solvents

Other: Aerosols

Question 14

Where are organochlorines stored in the body?

Answer 14

They are lipophilic - so they are stored in body fat

**when the patient needs to metabolize fat for energy - the toxin can be redistributed throughout the bloodstream causing a re-exposure

Question 15

Most organochlorines can be measured in the _____ fraction

Answer 15

lipid

and other tissues either as a base chemical or metabolite

Question 16

What is the mode of action of DDT-type organochlorines?

Answer 16

Neuronal membrane permeability or transport of Na and K is altered – Axonal Na channels remain OPEN and K channels do not open completely = Continued neurotransmitter release and hyperexcitablity of the nerve

Question 17

What is the mode of action of Chlorinated alicyclic organochlorine pesticides?

Answer 17

They are GABA antagonists - they bind but do not activate to GABA - blocking the actions of GABA –> Chloride ion channels don’t open —> Inhibition of CL flow into the nerve will inhibit repolarization and cause hyper excitability of the nerve

Question 18

T/F: Organochlorine metabolites can be re-absorbed

Answer 18

TRUE

Biliary excretion is the major rout of decontamination: metabolites are lipophilic and can be re-absorbed

Excreted in milk, urine, feces

Question 19

What clinical signs will be seen in an animal with oraganochlorine toxicosis?

Answer 19

all signs will vary depending on exposure and patient factors..

CNS hyperstimulation is the main clinical sign

salivating, vomiting, weakness, incoordination, tremors, muscle fasciculation etc etc coma, death

Question 20

What pathological lesions will be present upon acute organochlorine toxicosis?

Answer 20

no specific lesions acutely

secondary changes will be noted from trauma from convulsions, congestion/edema of various organs

Question 21

T/F: There is no specific antidote for organochlorine pesticides

Answer 21

TRUE

decontamination is an important part of the treatment process

Question 22

T/F: Disruption of neuronal Na and K permeability is associated with the toxic effect of chlorinated alicyclic-type organochlorines

Answer 22

FLASE

This is the mechanism for the DDT type