London, July 22 (IANS): Emissions from the burning of fossil fuels are threatening the effectiveness of the radiocarbon dating technique that has been used for decades to accurately calculate the age of a wide range of artefacts, says a new study.

Burning fossil fuels, such as coal and oil, gives out a type of carbon into the atmosphere that confuses the trusted dating technique, BBC reported on Tuesday.

It cited scientists as saying that by 2050, new clothes could have the same radiocarbon date as items 1,000 years old. Developed by Willard Libby in the late 1940s, the method measures carbon-14, a radioactive form of the element. It is produced in the atmosphere and then absorbed by plants through photosynthesis.

Animals that eat the plants ingest the carbon-14. Scientists are able to work out the age of almost anything organic by comparing the level of carbon-14 to non-radioactive carbon in the sample.

"As carbon-14 decays over time the fraction will decrease so that's how we use it for dating," the study's author Heather Graven was quoted as saying.

"But we can also change this ratio of radioactive carbon to total carbon, if we are adding non-radioactive carbon and that's what's happening with fossil fuels, we get this dilution effect."

The research has been published in Proceedings of the National Academy of Sciences.