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Two of the UK's biggest clubs have announced they will host onsite drug testing for the first time.
Charity The Loop will operate at Drumsheds in London and the Warehouse Project in Manchester, checking any confiscated or surrendered substances.
If testers find something potentially dangerous - stronger than usual, contaminated, or sold as something it's not - they'll put a warning out to clubbers.
The Loop's CEO Katy Porter tells BBC Newsbeat it doesn't endorse drug-taking, but accurate information can save lives if people choose to use them.
The charity's mainly tested at summer music festivals since 2013, but has been granted permission by the government to test at both venues.
Katy says being able to test throughout the year allows The Loop to monitor trends in the "ever-changing" drug market more accurately.
"Every point in time that we're testing, we're getting real-time information," she says.
"So if we have a pause in that, we've got some delay in terms of understanding."
Katy says an example of those trends came during the summer, when one in ten MDMA pills tested contained 200 milligrams - a much higher strength than normal.
Katy says more recent testing has seen the frequency increase to one in four pills.
"That poses risk for people, if they think they might be taking something of lower strength and it turns out to be much stronger than they think it is," she says.
The charity will perform "back-of-house" tests out of sight of the public, as opposed to "front-of-house" tests where people can take drugs to have them tested.
Drug checking is widely supported by event organisers and authorities as part of an approach known as harm reduction.
They will take measures to stop drugs getting into venues and arrest anyone supplying drugs, but most accept it's impossible to stop people from taking them completely.
Harm reduction tries to make people aware of the risks and warn them about any unusual or dangerous substances in circulation.
Sam Spencer, from Drumsheds, said testing at the venue was "a significant move" towards keeping audiences safer.
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