Featured Research

from universities, journals, and other organizations

Measuring The Effects Of Very Low Doses: New Study Challenges How Regulators Determine Risk

Date:
January 3, 2007
Source:
University Of Massachusetts Amherst
Summary:
A new study of a large U.S. National Cancer Institute database provides the strongest evidence yet that a key portion of the traditional dose-response model used in drug testing and risk assessment for toxins is wrong when it comes to measuring the effects of very low doses, says Edward J. Calabrese, a scientist at the University of Massachusetts Amherst. The findings, based on a review of more than 56,000 tests in 13 strains of yeast using 2,200 drugs, are published in the journal Toxicological Sciences and offer strong backing for the theory of hormesis, Calabrese and his colleagues contend.

A new study of a large U.S. National Cancer Institute database provides the strongest evidence yet that a key portion of the traditional dose-response model used in drug testing and risk assessment for toxins is wrong when it comes to measuring the effects of very low doses, says Edward J. Calabrese, a scientist at the University of Massachusetts Amherst. The findings, based on a review of more than 56,000 tests in 13 strains of yeast using 2,200 drugs, are published in the journal Toxicological Sciences and offer strong backing for the theory of hormesis, Calabrese and his colleagues contend.

Calabrese says the size of the new study and the preponderance of evidence supporting hormesis, a dose-response phenomenon in which low doses have the opposite effect of high doses, is a breakthrough that should help scientists assess and predict risks from new drugs, toxicants and possibly carcinogens. Calabrese says, "This is a fundamental biological principle that has been missed."

Calabrese says that the field of toxicology got the dose response wrong in the 1930s and this mistake has infiltrated all regulations for low-dose exposures for toxic chemicals and drugs. These low-dose effects can be beneficial or harmful, something that the regulations miss because they are currently based on high-dose testing schemes that differ greatly from the conditions of human exposures.

In this latest study, which uses data from a large and highly standardized National Cancer Institute tumor-drug screening database, Calabrese says the evidence of hormesis is overwhelming. In the study, high doses of anticancer drugs frequently inhibit yeast growth, but at low doses they enhance growth, exactly what the homesis model predicts.

Whether one accepts the hormesis theory is not the critical public policy issue, according to Calabrese. He says that the major issue is that the risk assessments models used by the federal Environmental Protection Agency and the Food and Drug Administration fail to accurately predict responses in the low-dose zone, that is, where people live most of their daily lives.

Calabrese also says challenging the existing dose-response model has profound public policy and health implications. "I believe the hormesis model is the fundamental dose-response and government testing and risk assessment procedures should reflect that," Calabrese says. For example, in environmental regulations, it has been assumed that most carcinogens possess real or theoretical risks at low levels, and therefore must be nearly completely removed from the environments to assure public safety. Some would contend that if hormesis is the correct model for very low levels, that cleanup standards may have to be significantly changed. Others, however, see the evidence as insufficient for such radical change and worry about other factors that can influence the effects of chemicals in low doses. The new study promises to add fuel to the debate, Calabrese says.

Calabrese also suggests that the findings may have important implications for the pharmaceutical industry and medical practices. He says that hormesis is likely to identify new life-saving drugs that were missed through traditional testing and to markedly improve the accuracy of patient dosing, which will not only improve health outcomes but also reduce adverse side effects.


Story Source:

The above story is based on materials provided by University Of Massachusetts Amherst. Note: Materials may be edited for content and length.


Cite This Page:

University Of Massachusetts Amherst. "Measuring The Effects Of Very Low Doses: New Study Challenges How Regulators Determine Risk." ScienceDaily. ScienceDaily, 3 January 2007. <www.sciencedaily.com/releases/2007/01/070102095841.htm>.
University Of Massachusetts Amherst. (2007, January 3). Measuring The Effects Of Very Low Doses: New Study Challenges How Regulators Determine Risk. ScienceDaily. Retrieved July 23, 2014 from www.sciencedaily.com/releases/2007/01/070102095841.htm
University Of Massachusetts Amherst. "Measuring The Effects Of Very Low Doses: New Study Challenges How Regulators Determine Risk." ScienceDaily. www.sciencedaily.com/releases/2007/01/070102095841.htm (accessed July 23, 2014).

Share This




More Health & Medicine News

Wednesday, July 23, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Courts Conflicted Over Healthcare Law

Courts Conflicted Over Healthcare Law

AP (July 22, 2014) Two federal appeals courts issued conflicting rulings Tuesday on the legality of the federally-run healthcare exchange that operates in 36 states. (July 22) Video provided by AP
Powered by NewsLook.com
Why Do People Believe We Only Use 10 Percent Of Our Brains?

Why Do People Believe We Only Use 10 Percent Of Our Brains?

Newsy (July 22, 2014) The new sci-fi thriller "Lucy" is making people question whether we really use all our brainpower. But, as scientists have insisted for years, we do. Video provided by Newsy
Powered by NewsLook.com
Scientists Find New Way To Make Human Platelets

Scientists Find New Way To Make Human Platelets

Newsy (July 22, 2014) Boston scientists have discovered a new way to create fully functioning human platelets using a bioreactor and human stem cells. Video provided by Newsy
Powered by NewsLook.com
Gilead's $1000-a-Pill Drug Could Cure Hep C in HIV-Positive People

Gilead's $1000-a-Pill Drug Could Cure Hep C in HIV-Positive People

TheStreet (July 21, 2014) New research shows Gilead Science's drug Sovaldi helps in curing hepatitis C in those who suffer from HIV. In a medical study, the combination of Gilead's Hep C drug with anti-viral drug Ribavirin cured 76% of HIV-positive patients suffering from the most common hepatitis C strain. Hepatitis C and related complications have been a top cause of death in HIV-positive patients. Typical medication used to treat the disease, including interferon proteins, tended to react badly with HIV drugs. However, Sovaldi's %1,000-a-pill price tag could limit the number of patients able to access the treatment. TheStreet's Keris Lahiff reports from New York. Video provided by TheStreet
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:

Breaking News:
from the past week

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile: iPhone Android Web
Follow: Facebook Twitter Google+
Subscribe: RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins