The Senate Subcommittee on Superfund and Environmental Health is holding an oversight hearing this morning about efforts to protect public health under Superfund, a federal program that manages the nation's most toxic waste sites.

As Sen. Barbara Boxer noted in her opening remarks, one in four U.S. residents lives within four miles of a Superfund site, including 10 million children. Yet cleanup efforts have slowed to a virtual crawl. Indeed, a year-long investigation conducted by the nonprofit Center for Public Integrity released earlier this year found that:

* Cleanup work was started at about 145 sites in the past six years under President Bush, while the startup rate was nearly three times higher during the last six years of Bill Clinton's presidency;

* The number of sites declared "construction complete" in the six Clinton years averaged 79, while that average dropped to 42 a year under the Bush administration; and

* The EPA's 2007 target for construction completions was 40 sites, but it has been scaled back to 24. The 2008 target is 30 sites, according to the EPA's 2008 budget request.

CPI also found that the number of cleanups being carried out by the polluters responsible for the waste has dropped by more than 50 percent between the two administrations. Companies conducted cleanup activities at 473 sites from 1995 to 2000, but at only but at only 210 sites from 2001 to 2006. Cost recoveries from responsible companies have also dropped markedly, from about $320 million each year in the late 1990s to about $60 million in the past two fiscal years.

As a result, there 517 sites across the country where human exposure and/or contaminated groundwater migration are not under control. The region we consider the South -- Alabama, Arkansas, Florida, Georgia, Kentucky, Louisiana, Mississippi, North Carolina, South Carolina, Tennessee, Texas, Virginia and West Virginia -- is home to 102 of these uncontrolled sites.

EPA officials have blamed the slowdown in cleanups on the difficult nature of the remaining sites. But another reason the program is in such dire straits is due to Congress's 1995 decision to allow a Superfund tax levied on polluters such as the petroleum and chemical industries to expire. President Bush has refused to reinstate the tax, depleting the program's trust fund and forcing taxpayers to bear cleanup costs. This fall marks four years since the trust fund went broke.

Among those testifying at today's hearing is Lenny Siegel of the California-based Center for Public Environmental Oversight, who is asking Congress to take action to replenish the fund. Legislation has been submitted in Congress to renew the polluter pays tax; for more on those bills, click here and here.

NOTE: For some interesting reading on Superfund, check out Superfund365, a project led by Brooke Singer, a New York-based professor of new media who's spending a year traveling around the country documenting some of the most hazardous Superfund sites. For a list of the sites she and her team plan to write about, click here. To read about my own childhood encounters with hazardous waste as documented by the project, click here.