Digital liberties group the Center for Democracy and Technology and e-commerce trade group NetChoice raised concerns that the new rules may target too many websites.
"COPAA should stay focused on websites that knowingly communicate with children -- not cast a net so wide it is impossible to comply with," Steve DelBianco, executive director of NetChoice, said by email. "I'm amazed at the ambiguity in determining whether a site is covered by COPPA. Despite two years of deliberation, the FTC still has not provided clarity the e-commerce industry needs."
Web sites that serve a mixed audience could be vulnerable to FTC enforcement under COPPA, he added.
The new rules' definition of when a website is directed to children "could expand COPPA's reach to general audience sites and confuse website owners as to whether these new rules apply to them," CDT said in a statement. This will likely prompt more sites to ask for age verification from all users before allowing access, the group said.
The new COPPA rules come just days after the FTC released a report saying that many mobile kids' apps collect information without getting parental consent.
In the past eight days, privacy group the Center for Digital Democracy has filed two COPPA complaints with the FTC, one against popular mobile children's game Mobbles and the second against television network Nickelodeon and mobile game-maker PlayFirst.
The new FTC rules are a "major step forward," although the CDD will be on the lookout for loopholes, said Jeffrey Chester, executive director the group.
"We are especially gratified that this decision puts to rest the longstanding and disingenuous claims by the digital marketing industry that cookies and other persistent identifiers are not personally identifiable information," he said in an email. "The revised rules also address the increasingly pervasive use of geolocation, behavioral targeting, and social media data collection."
Grant Gross covers technology and telecom policy in the U.S. government for The IDG News Service. Follow Grant on Twitter at GrantGross. Grant's e-mail address is email@example.com.