Map exposure pathways
Trace how a toxin moves from its source to a person's body to decide who is actually exposed.
- Source, pathway, receptor idea: An exposure pathway only exists if a toxin travels from a source, along a route, to a person who actually contacts it.
- Air, water, soil, and food as carriers: Knowing a toxin can ride in air, water, soil, or food anchors why route matters for who gets exposed.
Prerequisites are inferred: pending teacher review.
Re-learn the skill with worked practice and clear examples.
An exposure pathway links a source, a route through air, water, soil, or food, and a route of entry into the body. All three must connect for exposure to occur.
Pesticide is sprayed on a field (source). Wind carries the spray as a fine mist into a nearby schoolyard, where children are outside. Which best describes the completed exposure pathway?
Reviewed- A.Source: field; carrier: air; route of entry: breathing the mist
- B.Source: children; carrier: soil; route of entry: skin only
- C.There is no pathway because pesticide is not a toxin
- D.Source: schoolyard; carrier: water; route of entry: swallowing
Show the worked solution ▾
Answer: A. Source: field; carrier: air; route of entry: breathing the mist
- Step 1: Name the source: The pesticide is released at the sprayed field, so the field is the source.
- Step 2: Follow the carrier and entry: Wind (air) carries the mist to the children, who breathe it. Air carrier plus breathing it in completes the pathway.
Why it's right: The field is the source, air is the carrier, and breathing the mist is the route of entry: a complete, correctly ordered pathway.
- B: The children are exposed, not the source, and the carrier here is air, not soil.
- C: Pesticide is a toxin; harm does not require it to be 'natural' or not.
- D: The carrier is wind-borne air, not water, and the children breathe it rather than drink it.
Aligned to Environmental health: exposure pathway mapping · reading level ~grade 9
- A health department maps a 'completed pathway' for a contaminated well: source (leaking tank) → groundwater → drinking water → swallowing: to decide whether to warn residents.
Fill these in as you work through the lesson.
- Toxin (the harmful substance itself):
- Exposure (happens only when the substance reaches a body):
- Source (where the substance starts):
- Route of entry (breathe, swallow, or touch):
An exposure pathway needs a where the toxin starts, a route it travels, and a person who finally makes with it.
- Lead from old pipes dissolves into tap water that families drink. Name the source, the route, and how it enters the body.
- Why is a buried toxin that nobody ever touches, breathes, or eats not yet an exposure?
- Smoke from a factory drifts over a neighborhood and people breathe it. Which route of entry is this?
A factory dumps a chemical into a creek. Downstream, a family uses creek water for cooking and bathing. List the source, the route the chemical travels, and at least one way it could enter a person's body.