8.12 Pollution and Human Health

Pollution's health toll

Pollutants cause disease through multiple pathways: pathogens in water cause acute illness (cholera, dysentery, typhoid), toxic chemicals (heavy metals, pesticides) cause chronic disease, and air pollutants cause respiratory/cardiovascular problems. Effects depend on dose, exposure duration, and individual sensitivity — children, elderly, and pregnant people are often most vulnerable.

Dose-response relationships

A dose-response curve shows how organism response changes with pollutant dose. Key values: LD50 (lethal dose killing 50% of a test population) and ED50 (effective dose causing a response in 50%). Lower LD50 = more toxic substance. Some pollutants show a threshold below which no effect occurs; others (like carcinogens) may have no safe threshold.

Specific pollutant-disease links

Lead causes neurological damage, especially in children (lowered IQ). Mercury (biomagnified in fish) causes nervous system damage (Minamata disease). Particulate matter and ozone worsen asthma and cardiovascular disease. Persistent organic pollutants (POPs) like DDT and PCBs bioaccumulate and biomagnify, causing endocrine disruption and cancer risk.

Key terms

LD50

The dose of a substance that kills 50% of a test population; lower LD50 = more toxic.

ED50

The dose that produces a specific effect in 50% of a test population.

Dose-response curve

A graph showing how the severity/likelihood of an effect changes with the dose of a substance.

Minamata disease

Severe neurological disorder caused by mercury poisoning from contaminated fish in Japan.

Persistent Organic Pollutants (POPs)

Chemicals like DDT and PCBs that resist breakdown, bioaccumulate, and biomagnify, causing long-term health risks.

Try an AP-style question

Which health problem is linked to lead exposure in children?

1. Faster physical growth
2. Improved memory and focus
3. Stronger bones and teeth
4. Brain and nervous system damage