Lecture 3 and 4 - Environmental toxins

What are some of the most common toxicants in dogs?

-Ibuprofen

-Chocolate

-Ant and roach baits

-Rodenticides

-Acetaminophen

-Pseudoephedrine (sudafed)

-Thyroid hormone

-Bleach

-Fertilizer

-Hydrocarbons

What are the most common toxicants in cats?

-Canine flea/tick meds

-Other topical insecticides

-Venlafaxine

-Glow jewelry

-Lilies

-Liquid potpourri

-NSAIDs

-Acetaminophen

-Anticoagulant rodenticides

-Amphetamines

What are some of the most common toxicants in horses?

-Botulism (haylage contamination)

-Ionophores

-Cantharidin

-Hemlock

-Red maple

-Oleander

-Yew

-Pyrrolizidine alkaloids (ragwort)

-Rodenticides and pesticides

-Fumonsins (moldy grain)

What are some of the most common toxicants in livestock?

-Lead

-Nitrates

-Bluegreen algae

-Salt (pigs)

-Copper (sheep)

-Various grasses

-Bracken fern

-Aflatoxins (contaminated grains)

-Ergotism (mycotoxin)

-Zeralenone (mycotoxin - pigs)

What is an important principle of toxicology?

-Most toxicant exposures are environmental

-Need to measure, monitor, and manage environment 

Explain mechanisms of toxicity

-Lipophilic chemicals become trapped in adipose

-Mitotoxicants (interfere with mitochondrial metabolism)

What are the clinical effects of DDT in birds? In fish? In invertebrates?

-Birds: moderately and acutely toxic, causes reproductive problems, causes eggshell thinning 

-Fish: highly acutely toxic, affects membrane function and enzyme systems

-Invertebrates: Moderately acutely toxic, causes reproductive, developmental, cardiovascular, and neurological changes

How is mercury toxic?

-Inhalation of vapors

-Interfere with cellular metabolism

What is the minamata disease outbreak?

-Consumption of mercury contaminated fish

-Caused poor coordination, seizure and epilepsy, deformed limbs, mental retardation

What are the ecosystem impacts of microplastics?

-Habitat disruption

-Ingestion by plankton and filter feeders

-Bioaccumulation in food webs

What are the human health concerns for microplastics?

-Chemical leaching from plastics

-Microplastics in food products

What are mitigation strategies for microplastics?

-Policy interventions

-Public awareness

-Innovations in material science

What is risk?

Probability that a particular hazard will occur under specific exposure conditions

What is a hazard?

Capability of a substance to cause an adverse effect

What is a risk assessment?

Process by which hazards, exposures, and risk are determined

What is the risk equation?

Risk = toxicity x exposure

What are the 4 components of a risk assessment?

1. Toxicant identification

2. Toxicant evaluation

3. Exposure evaluation

4. Risk estimate

What is toxicant identification? What does it involve?

-Characterization of innate adverse toxic effects of different agents

-Physical/chemical properties, exposure properties, host factors

What is the dose-response assessment?

Relationship between dose and incidences of adverse effects

What is exposure evaluation?

Measurement or estimation of intensity, frequency, and duration of exposures

What is the risk estimation?

Estimation of incidence of health effects under various exposures