(Dow Jones) The securities industry isn't alone in its concerns about sweeping regulatory changes being thrust into motion too quickly. Some high-profile bureaucrats agree.

Kathleen Casey, one of the Securities and Exchange Commission's five commissioners, wants her agency to proceed with caution while implementing the Dodd-Frank financial regulatory reform law.

"The likely impact will be enormous and we have no idea of the actual costs in years to come," she says. Those costs "will be more substantial and more significant than legislators and regulators have considered."

Concerns about a rush to regulate were a recurring theme at the annual SEC Speaks conference Friday. The Washington D.C. event is sponsored by the Practising Law Institute, a non-profit continuing education service for lawyers.

The sentiments mirror those raised earlier by the Securities Industry and Financial Markets Association, or Sifma, a trade group for mid-sized and large brokerages. It argues that investors would likely pay higher costs if a possible fiduciary standard for brokers who give personalized investment advice prohibited certain practices, such as commission-based compensation or purchasing municipal bonds from a broker who underwrote the offering.

Sifma voices support for a new federal fiduciary standard of care for investment advisers and certain brokers, yet is pushing a slow-but-steady approach to change. It also says it will "work with the SEC to ensure that the broker-dealer role is not hindered," it wrote.

Some of the SEC's five commissioners question whether they can adequately consider the numerous rulemakings and studies required by Dodd-Frank in the timeframes set by Congress.

"This has less to do with resources than with the capacity of the commission," Casey says.

The rigorous mandate set by Congress includes completing numerous studies and rulemakings within 12 to 18 months subsequent to Dodd-Frank's enactment last July. Short public comment periods and time frames in which to consider those responses threaten to undermine the commission's strength and make the agency's upcoming new rules more susceptible to legal challenges. Casey says Congress needs to consider providing more time.

Casey is one of two Republican appointees on the commission, but isn't alone in raising concerns. "We need to take great care as we move forward," says Commissioner Luis Aguilar, a Democrat. He called the current pace of work at the SEC "inhumane."