What is a non threshold carcinogen?

What is a non threshold carcinogen?

Doses without a carcinogenic risk (no effect levels) can be determined for threshold based carcinogens. For non-threshold based genotoxic carcinogens, a no effect level would be a dose or exposure of zero.

Do carcinogens have a threshold?

While it has been generally accepted that genotoxic carcinogens have no dose threshold for their carcinogenic potential, there is increasing evidence that very low doses in fact are incapable of inducing tumours or preneoplastic lesions.

What is a non-genotoxic carcinogen?

Non-genotoxic carcinogens are substances that induce cancer through indirect stimulation of hyperplastic responses, without altering DNA, chromosome number or structure.

What is a non-threshold?

Linear no-threshold (LNT) is a model used in radiation protection to estimate the cancer risk caused by ionizing radiation. The LNT model assumes that radiation doses greater than zero will increase the risk of excess cancer or heritable disease in a simple proportionate manner in the low-dose range.

What is a non-threshold substance?

The substance which is not reabsorbed and excreted entirely from the body is called as Nonthreshold substance. For example, creatinine is a non-threshold substance.

Why are carcinogens assumed to have no threshold?

A practical no-observed-effect level could occur with genotoxic carcinogens. Effective detoxification, scavenging mechanisms and lack of activation could prevent DNA interaction. Critical DNA adducts are subject of error-free repair, which might be considered a major mechanism provoking a no-effect threshold.

What are the characteristics of non-genotoxic carcinogens?

Non-genotoxic carcinogens have been shown to act as tumor promoters (1,4-dichlorobenzene), endocrine-modifiers (17beta-estradiol), receptor-mediators (2,3,7,8-tetrachlorodibenzo-p-dioxin), immunosuppressants (cyclosporine) or inducers of tissue-specific toxicity and inflammatory responses (metals such as arsenic and …

What does hormesis mean?

Hormesis is a term used by toxicologists to refer to a biphasic dose-response to an environmental agent characterized by a low dose stimulation or beneficial effect and a high dose inhibitory or toxic effect.