One way to scare consumers out of buying fake designer cosmetics? Tell them what they contain.

City of London Police said Monday that they’ve found rat droppings, arsenic and lead in counterfeit makeup, as they announced a public safety campaign to warn the public against purchasing such products online.

“Laboratory tests have shown counterfeit perfume often contains poisonous chemicals including cyanide and even human urine,”  a police statement reads. “While fake cosmetics such as eyeliner, mascara, lipgloss and foundation have been found to contain toxic levels of chemicals and harmful substances such as arsenic, mercury and lead.”

Rat droppings and human urine may be ending up in these products because they’re often produced in unregulated factories overseas with no oversight on hygiene, Detective Superintendent Maria Woodall told the BBC. And their profits fund organized crime, she added.

Authorities estimated that consumers in the United Kingdom spend at least 90 million pounds — more than $141 million — annually on fake cosmetics.

Woodall said counterfeit hair curlers and driers can electrocute the people using them, and the authorities have had cases of fake makeup causing swelling.

“These are coming into direct contact with your skin. They’re very dangerous and who knows what the side effects will be because until they go on face skin, you’re not going to know,” she said. “We’re talking about human urine in perfume.”

These products show up in online stores and auction sites. Over the past 18 months, City of London Police’s property crime unit has seized more than 3.5 million pounds worth of fake cosmetics and suspended more than 5,500 Web sites peddling such products, according to police.

So how can consumers stay clear of fake makeup? Police warn that luxury brands rarely offer discounts, and they advise checking the spelling and URL on Web sites selling the items.

“Often the people behind these sites do not pay a lot of attention or care to this detail,” police said. “Fraudsters may also try to deceive you by slightly changing the spelling of a well-known brand or shop in the Web site address.”

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