LONDON — British consumers who buy counterfeit beauty products could be exposing themselves to cyanide, arsenic, mercury, lead, human urine, rat droppings and rat poison, according to the City of London Police.

On Monday, the London force’s Police Intellectual Property Crime Unit launched an awareness campaign to highlight the rise in counterfeit beauty products. The campaign — called “Wake up — don’t fake up!” — noted that counterfeit makeup is often produced in unsanitized and unhygienic factories, with rat droppings and rat poison having been found in some cosmetics that police have seized.

Those poisons can cause skin irritation, swelling, rashes and burns, along with long-term health problems, the police said.

The campaign detailed that as part of one criminal operation that the PIPCU dismantled last year, it seized 4,700 counterfeit products purporting to be by a popular U.K. beauty brand, which included products such as foundation, bronzer, lip-gloss, eye shadow and eyebrow pencils. A spokeswoman for the police force declined to comment on the name of the brand.

In the case of electrical beauty devices, the report said, counterfeit devices are not subject to vigorous safety tests, meaning they could cause electrocution, overheat or catch fire.

The report also highlighted that online shopping had made checking the authenticity of a product more difficult for consumers. “Consumers cannot gauge the look and feel of a product as they did before when buying on the high street,” the report said of online shopping. “Generic stock images are also frequently used to deceive customers into believing they are buying the real deal.”

The PIPCU said in the last 18 months, it has suspended more than 5,500 Web sites selling fake luxury branded goods, and has seized 3.5 million pounds, or $5.5 million worth of goods in that time. The unit was set up in September 2013, with funding from the U.K.’s Intellectual Property Office.

Detective superintendent Maria Woodall of the City of London Police, who oversees the PIPCU, commented: “Criminals are exploiting every opportunity to fool customers into buying counterfeits in order for them to make some quick cash — putting people’s health, homes and lives at risk.” She added that the rogue sites often then compromise customers’ payment details. “Criminals behind [counterfeit sites] have used [customers’] payment details to make further purchases or even use their personal details to set up hundreds of illegal sites selling counterfeit goods,” she said.

Among firms that have had counterfeit versions of their products sold recently in the U.K. are MAC, Estée Lauder, Benefit and Urban Decay. Gregg Marrazzo, senior vice president and deputy general counsel at The Estée Lauder Cos. Inc., noted “purchasing…products at authorized stores and counters is the only way to ensure that the product you are receiving is genuine and meets the safety and quality standards expected,” adding that “counterfeit products can quite often appear to be authentic.”

“We continue to work with law enforcement and the courts in an effort to address any outlet distributing or selling counterfeit product to minimize the potential danger that this could cause to consumers,” Marrazzo said.

Urban Decay said its products “are sold exclusively through selected retail channels and our Web site.”

“If some of our products are sold elsewhere, it is without our knowledge and we therefore encourage our customers to be vigilant,” the company said.

To guard against purchasing fake products, the PIPCU advised customers that legitimate designer beauty products are “rarely discounted,” and to check details, such as whether the trader has a postal address and to check the spelling and grammar of Web sites as an indication that they’re fake. It also advised shoppers that the Web site brand-i.org holds a list of genuine e-commerce sites and approved shops.

Sales of counterfeit goods in the U.K. are significant, with the City of London Police saying that British consumers spend at least 90 million pounds, or $141.5 million, on counterfeit goods each year.