EPA announces new chemical toxicity plan
30 March 2009
The US Environmental Protection Agency (EPA) has announced a new strategy for evaluating the toxicity of chemicals, after facing growing pressure to reform chemical safety regulations that have been in place for over three decades.
New regulations mean the agency will now rely less on animal testing to assess toxicity and risk, focusing instead on using advanced tools from fields like genomics, molecular biology and computational sciences.
The traditional risk assessment approach relies heavily on data generated through animal dosing studies, but the EPA must increasingly navigate complicated issues like cumulative exposures and genetic susceptibilities, even as the number of chemicals that require investigation continues to grow.
Although the EPA is charged with developing safety information on several thousand chemicals in the environment, the agency admits that the current system it uses to gather toxicity data is time-consuming, expensive and often fails to yield adequate information to determine which chemicals pose the most immediate dangers.
But the agency hopes its new strategic plan, released on last week, will enable access to data that can strengthen the basis for its chemical risk assessments and also reduce uncertainties around those final judgments.
The EPA has been accused of making questionable determinations about the toxicity of certain chemicals in the past, with Congress, chemical companies and others publicly questioning some of the agency's conclusions in recent years.
Congressional watchdog sounded the alarm
The congressional Government Accountability Office (GAO) in January recommended a complete overhaul of the EPA's Toxic Substances Control Act (TSCA), which regulates the introduction of new or already existing chemicals in the US. In fact, GAO concluded that the EPA 'lacks adequate scientific information on the toxicity of many chemicals that may be found in the environment - as well as on tens of thousands of chemicals used commercially in the United States.'
But now, sequencing of the human genome and concurrent investments in high throughput screening and other techniques have spurred biotechnology advances that enable a broad scale examination of the molecular and cellular targets of chemicals.
The EPA's new strategy aims to build understanding of the networks of genes that interact with the environment to produce so-called 'toxicity pathways' that create negative health effects upon exposure to certain agents. After identifying these toxicity pathways, the EPA wants to develop in vitro bioassays that will enable it to assess the effects of thousands of chemicals on these various pathways.
'Broadening this approach to the many toxicity pathways present in living systems allows a new avenue for identifying those chemicals that pose the greatest potential hazard,' the agency explains in its 35-page report detailing the new strategy. 'Knowledge of the toxicity pathways triggered by any one chemical will also allow targeting of specific in vivo tests to more fully characterise the potential hazard and risk.'
The EPA says its new strategy could significantly alter the tests that it requires to gauge chemical safety. The total number of tests and data required will not necessarily increase, but the types of tests being requested could change substantially.
The American Chemistry Council (ACC), a US chemical industry trade association, says it supports the 'development, standardisation and validation' of new alternative toxicology test methods. But the group warns that considerably more research will be needed to develop the science before high-throughput screening molecular approaches can be applied to chemical regulation.
'This research must include developing key science-based interpretation tools so that results from these advanced technologies can be translated into meaningful information that can be used effectively in decisions about priority setting and chemical safety,' says ACC spokesperson Tiffany Harrington.
Rebecca Trager, US correspondent for Research Europe
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