A company exhibits sex dolls at the 17th China Adult Toys and Health Care Products Exhibition in Guangzhou, Guangdong Province on November 6, 2015. Photo: CFP

As China's sex toy industry penetrates more and more people's bedrooms, experts have again called for industrial standards to be established to better regulate the almost unsupervised sector.More sex toys were sold on this year's Singles' Day on November 11 - the country's annual online shopping spree - than in previous years.A search of online retail platform Taobao for sex dolls yielded 61,900 hits as of press time. The three most popular models on the site, which cost between 150 to 600 yuan ($23-92) each, have been ordered 10,900 times in November so far.According to the Guangzhou-based New Express newspaper, an online pharmacy sold 500 sex dolls on November 11 and another sex doll store owner claimed that 2,500 sex dolls were sold on the same day.Citing Taobao data, the newspaper said that the number of sex toys being bought online has grown by 50 percent annually in recent years, with an estimated 30 million Chinese people buying sex toys online in 2015.Data released by market research firm Analysys International showed that the B2C market volume of sex toys in China topped 3.38 billion yuan in 2013, up 73.6 percent on the previous year. The figure will grow at 58 percent annually in the next three years, Analysys estimated.According to a survey conducted by sex toy company JINGVO International in 2014, over 75 percent of the 10,000 respondents said they would like to try sex toys. Some 43 percent said they tend to purchase sex toys online, China Economic Net reported.The survey also found the main group that buys sex toys are couples and that they tend to see product quality as the most important factor.The Taobao data also showed that 65 percent of customers are aged between 18 and 29 and those aged between 30 and 39 make up 26 percent of buyers, New Express reported.Li Jihong, deputy secretary-general of the Sexology Association of Guangdong Province, claimed that the industry's growth is caused by the gender imbalance, New Express reported.Peng Xiaohui, a sexologist at Wuhan's Central China Normal University, told the Global Times on Wednesday that people's increasing open-mindedness has contributed to the booming industry."The younger generation is more sexually active and has a stronger purchasing power and willingness to try these things," Peng said, adding that the more sex education people receive, the more the domestic market for sex toys will grow and develop.The production of sex-related products was overseen by the food and drug administration until 2012. Now, different products are managed by different government departments including the family planning department and the health authorities. However there is no specific department responsible for regulating the production of sex toys, said an Analysys report issued in February.Chinese sexologists have called for a standardization of the industry since 2012, but little has been done."As China produces 70 percent of the world's sex toys, some big manufacturers that conduct international trade will use international standards such as a FDA certification, while the domestic market remains poorly-regulated," Tony Tong, founder of New Kinsey, a Shanghai sexology research institute, told the Global Times.According to research conducted by Su Weiguo, chairman of the China Council on the Science of Sex, some vibrators are made from industrial silicone rather than materials designed for human contact.Tong said that low-quality silicone that can easily get dirty may lead to bacterial infections and the inflammation of sexual organs.Tong added that polyvinyl chloride (PVC) products tainted with the carcinogenic plastics were common on the market 20 years ago, and can still be found in some cheap products today.Su's research also found that battery-powered vibrators are sometimes made with faulty insulation that could give users a shock in a sensitive place."I clean my sex doll after I use it. Some parts of it have become mouldy, but there is no inflammation or other diseases. It is safe," a sex doll user told the Global Times.Many comments on Taobao sex toy stores complain about the "sour and sticky" plastic smell of the products as well as their dirty packages. Others wrote of feeling "uncomfortable" after using the products, with some claiming their genitals became inflamed. A few sex doll users wrote that their shoddy inflatable lovers exploded during sex.