dose Low Carcinogenesis Low dose Anticarcinogenesis Hormesis can be seen in the same animal species Richard Wilson, Harvard University Frank Pompei, Exergen Amherst, MA Tuesday, June 11th 2002
Regulatory posture for 30 years
If an increase in tumors in any site is seen after administration of a chemical,
label it carcinogenic and ban it.
This has led experimentation e.g. NTP
Choose most sensitive gender/species Ignore anticarcinogenic effects Allow ad-libitum feeding (simpler and "more sensitive" )
Sir Richard Peto and others; if the cancer is identical to one that occurs naturally, adding a small dose is (differentially) linear (Taylor's theorem) But what do data say?
It has long been known that alcohol consumption displays hormetic effects (reduction in mortality at low doses and increase in high doses) This is attributed to addition of two effects: reduction in incidence of stroke increase in cancer (and antisocial behavior)
Annual Death Rate By Daily Alcohol Consumption
Death Rate (Per 100,000) 2000 1500 1000 500 0 0 0.5 1 2 3 4 5 6 Number Average of Drinks Per Day
Alcohol-augmented conditions Cardiovascular disease All causes
Percentage of chemicals classified as carcinogens.
Percentage of chemicals classified as anticarcinogens
About 5% of cases show anticarcinogenic responses in one site and carcinogenic responses in another. They add to what is seen in alcohol
Carcinogenic responses are easiest to see when there is an increase in rare tumors Anticarcinogenic responses can only be seen as a reduction in common tumors. The sum will display hormesis even if each is individually linear with dose
Schematic picture showing how this leads to hormesis
Kociba's ...