L1 Special Topics in Environmental Toxicology

These flashcards contain key information and concepts from the PH 179 lecture on Environmental Toxicology to aid in exam preparation.

What is the main objective of the PH 179 course?

To understand types of toxic substances in the environment and their effects on health, environment and ecosystems.

What are the components of course grading in PH 179?

Mid-term exam (35%), Final exam (35%), Refresher quizzes (30%).

What types of questions are in the mid-term and final exams?

Closed book exams with multiple choices, short answer, and essay questions.

What is the significance of the No Observed Adverse Effect Level (NOAEL)?

It is the highest exposure level at which there is no significant increase in adverse effects.

Explain the difference between acute and chronic exposure to toxicants.

Acute exposure refers to a high level of exposure over a short period, while chronic exposure involves low levels over a long duration.

What does the term 'bioaccumulation' refer to?

It refers to the accumulation of toxic substances in an organism from the environment over time.

What does the reference dose (RfD) represent in toxicology?

RfD is an estimate of the daily exposure to a toxicant that is not expected to cause adverse effects.

What determines the route of exposure to a toxicant?

Routes can include skin (dermal), gastrointestinal (oral), respiratory (inhalation), and others.

Why is the liver significant in the metabolism of toxicants?

The liver is the primary organ for metabolizing toxicants, converting them into more water-soluble forms for excretion.

How do reactive oxygen species (ROS) relate to toxicity?

ROS can cause damage to cells, leading to adverse health effects, such as DNA damage and cell death.

What is the therapeutic index (TI)?

TI is the ratio of the toxic dose (TD50) to the effective dose (ED50); a larger TI indicates a safer drug.

Describe a case study associated with water intoxication. What occurred?

In 2007, Jennifer Strange died after drinking ~6 liters of water in 4 hours during a contest, leading to water intoxication.

What are the primary enzymes involved in Phase I metabolism in the liver?

Cytochrome P-450 enzymes are key in Phase I metabolism, adding polar groups to toxicants.

What is the impact of long half-life toxicants in the environment?

Toxicants with long half-lives can persist and accumulate in the environment, leading to greater ecological and health risks.

What does the term 'toxicity' refer to?

Toxicity refers to the degree to which a substance can harm humans or animals.

Identify one method of detoxification of reactive oxygen species (ROS).

Superoxide dismutase is an important enzyme that detoxifies reactive oxygen species.

What role do transporters play in the absorption of toxicants?

Transporters can facilitate the movement of toxicants across cell membranes, influencing their bioavailability.

What is the impact of hydrophobic vs. hydrophilic properties on the distribution of toxicants?

Lipophilic (hydrophobic) toxicants can easily cross cell membranes, whereas hydrophilic molecules may require active transport.

How is the severity of a harmful effect determined in toxicology?

Severity is determined by factors such as dose duration and the toxicity of the substance.

What are some common environmental toxicants mentioned in the course?

Common toxicants include formaldehyde, mercury, lead, asbestos, and pesticides like glyphosate.

What is meant by 'dose-response relationship'?

It describes the relationship between the dose of a toxicant and the magnitude of the response it produces.

Discuss the role of kidney in the excretion of toxicants.

The kidneys filter blood to excrete polar, water-soluble toxicants in urine while reabsorbing lipophilic ones.

What health risks arise from drinking too much water?

Risks include hyponatremia and water intoxication, leading to symptoms such as headache and neurological effects.