Researchers began with field studies in China and collected thousands of fish over several years. They compared lakes with more pesticide contamination to lakes with little contamination. Populations in contaminated lakes had few older fish, while cleaner lakes had many older fish. The team interpreted this pattern as earlier death rather than a failure to reproduce.
Chemical analysis showed chlorpyrifos was the only compound consistently linked to signs of getting old. Scientists measured shorter telomeres and more lipofuscin in fish livers. In lab tests, long-term low doses similar to the wild caused progressive telomere shortening, more cellular aging and lower survival. Short, high doses caused quick toxicity and death but did not speed telomere shortening.
Chlorpyrifos is largely banned in the European Union but still used in China, parts of the United States and many other countries. The aging effects appeared at concentrations below current US freshwater safety standards.
Difficult words
- contamination — presence of harmful chemicals or dirt in something
- interpret — to explain the meaning of somethinginterpreted
- telomere — end part of a chromosome that protects DNAtelomeres
- lipofuscin — brown pigment in cells that shows aging
- compound — a chemical made of two or more parts
- concentration — amount of a substance in a volumeconcentrations
Tip: hover, focus or tap highlighted words in the article to see quick definitions while you read or listen.
Discussion questions
- Would you be worried if your local lake had pesticide contamination? Why or why not?
- What two measures did scientists use to show aging in fish (name them)?
- Should a chemical be banned if it harms animals? What would you decide and why?
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