People walk inside an Apple retail store in Shanghai August 25, 2011. (Photo: Aly Song / Reuters)

Even as Apple has made impressive gains in the China market—its stores here are often packed and occasionally even faked by retailers hoping to cash in on the company’s recognition—domestic environmental groups are questioning whether Apple is being a good corporate citizen in the country. A new report by a group of Chinese NGOs says suspected Apple suppliers are linked to some serious pollution cases, and Apple has refused to respond to specific allegations. The groups say they have found environmental problems at 27 Chinese manufacturers who they believe are suppliers to Apple. The allegations include severe pollution of a lake in the central city of Wuhan, complaints about noxious gases in Taiyuan and incomplete record keeping of hazardous waste by a plant in Beijing. Because Apple does not usually reveal its suppliers, the environmentalists have in many cases not been able to conclusively link the polluting companies to Apple, and are pushing the tech giant to provide answers.

This latest report is part of an investigation that was launched in 2009. The Chinese environmental groups began by looking at the sources of heavy metal pollution in China. Their investigations turned up links to suppliers of global IT companies, and last summer the groups outlined pollution cases and called on 29 multinationals to respond. In January they found serious problems with pollution and workplace health hazards at Chinese factories that supply some of the world’s biggest tech firms, and singled out Apple for the strongest criticism. Not only did factories that make parts for the company’s popular iPhones and iPads expose workers to toxic substances, but the NGOs say that Apple has largely avoided their inquiries. A spokesman for the Cupertino, Calif.-based company told the New York Times this week that Apple “is committed to driving the highest standards of social responsibility throughout our supply chain.” The Financial Times reported Wednesday that Apple had contacted Ma Jun, director of the Institute of Public and Environmental Affairs, one of the report’s contributors, to say that some of the Chinese manufacturers weren’t Apple suppliers and begin a dialogue over the allegations.

Apple conducts its own audits of suppliers and publishes regular responsibility reports. Its 2011 progress report addressed some of the problems raised by the Chinese environmentalists. It acknowledged the poisoning of workers who used toxic cleaners to wipe screens at a Suzhou factory run by the Taiwanese firm Wintek, and a spate of worker suicides last year of workers for Foxconn, a company that makes gadgets for big name clients including Apple, Sony, HP and Dell. But aside from Wintek and Foxconn, Apple kept other company names secret and thus “succeeded in avoiding true public supervision of its supply chain,” the environmental groups claim in their latest report.

The report praised the responses of several companies including Vodaphone, Siemens and Nokia for making “significant progress toward responsible supply chain management.” Even Foxconn, which has been under intense scrutiny after 12 employees in their late teens or early 20s jumped from company buildings in the first half of 2010, ranked slightly higher than Apple on the NGOs’ tally of responses.