63-73 Doses and Pathogens

APES 2024

Manure from concentrated animal feeding operations is a problem because of

Manure from concentrated animal feeding operations is a problem because of

volume and can also contain hormones and antibiotics that are given to the animals

Manure lagoon

Human-made pond lined with rubber built to handle
large quantities of manure produced by livestock

After the manure is broken down by bacteria, it is

spread onto fields as fertilizers

LD50/ED50=

the amount of toxicant required to kill (affect) 50% of the subjects
• A high number indicates low toxicity

Threshold dose

level where certain responses occur
• Organs can metabolize or excrete low doses of a toxicant

Sometimes a response decreases as a dose increases

U- or J-shaped or an inverted-U dose-response curve

occur with endocrine disruptors

• The hormone system is geared to respond to minute concentrations (e.g., hormones)
• vulnerable to extremely low concentrations of chemicals
• Thousands of studies show that endocrine disruptors affect reproduction, development, immune functions, nervous systems, etc

Acute exposure

high exposure to a hazard for short periods of time
• discrete events: ingestion, oil spills, nuclear accident, etc

Chronic exposure

low exposure for long periods of time

• More common but harder to detect and diagnose
• Affects organs gradually: lung cancer, liver damage
• Cause and effect may not be easily apparent

Chronic disease

Toxic Substances Control Act (1976)

the EPA monitors chemicals made in or imported into the U.S.
• can ban substances that pose excessive risk

Many health advocates think the TSCA is too weak because

Of 83,000 chemicals, only five have been restricted
• Only 10% of chemicals have been tested for toxicity
• Fewer than 1% are regulated
• Almost none have been tested for endocrine, nervous, or immune system damage

As warmer climate zones (equatorial) spread north and south into subtropical and temperate zones

Pathogens, infectious diseases, and vectors are spreading into areas where the disease has not been before

Emergent infectious disease

An infectious disease that has not been previously described or has not been common for at least 20 years

The emergence of new diseases

Since the 1970s, new diseases, or diseases that have been rare for more than 20 years, have been appearing throughout the world at a rate of approx. one per year

Disease

Any impaired function of the body with a characteristic set of symptoms

Infectious disease

A disease caused by a pathogen

Acute disease

A disease that rapidly impairs the functioning of an
organism

Chronic disease

A disease that slowly impairs the functioning of an
organism

Dysentery

caused by untreated sewage in streams and rivers

Mesothelioma

type of cancer caused mainly by exposure to asbestos

Respiratory issues and overall lung function impacted by

elevated levels of tropospheric ozone

Plague

disease carried by organisms infected with the plague bacteria
• Transferred to humans via the bite of an infected organisms

Vector

an organism that transfers a pathogen to a host
• Or through contact with contaminated fluids or tissues ex. mosquito

In low-income countries, the top risk factors leading to chronic disease are

associated with poverty, including unsafe drinking water, poor sanitation, and malnutrition

Risk factors for chronic disease in high-income countries include

increased availability of tobacco, and a combination of less active lifestyles, poor nutrition, and overeating that leads to high blood pressure and obesity