Toxicology basics

Nine short ideas that toxicologists use every day. Each takes a few minutes, has a picture, and ends with a way to use it: on a case you're reading about, or in small changes at home.

9 concepts · 27 minutes in all · best read in order

Dose and response
How much, how often and for how long decide what a substance does. The first question to ask of any claim.
3 min · Use it on a case
NOAEL and LOAEL
The two doses a study gives, and how agencies step down from them to a daily limit.
3 min · Use it on a case
Acute and chronic
A single spike and years of small doses are different questions, and can even affect different organs.
3 min · Use it day to day
Aggregate exposure
One substance from every source, added up. Limits apply to the total, not to each product.
3 min · Use it day to day
Mixtures
People meet many substances at once. The default is to add them up; whether they do more than add is still being studied.
3 min · Use it day to day
Sensitization
Some substances teach the immune system to react. After that, the question isn't only how much, but whether the body has learned it.
3 min · Use it day to day
Reading the odds
Risk is a chance with a base. Absolute and relative risk, how to turn percentages into people, and why a big percentage can be a small change.
3 min · Use it on a case
Cancer and non-cancer
Two ways agencies draw the line. Most effects get a daily limit; cancer often gets a straight line and an extra lifetime chance.
3 min · Use it on a case
Groups and individuals
Limits keep risk low for groups, with room for the people who react more. Your own case depends on where you sit.
3 min · Use it on a case