Difference between revisions of "Mixtures/multiple exposures"

Revision as of 14:43, 13 March 2007

Scope
Mixtures/multiple exposures describes the ways to deal with exposures to mixtures (multiple exposures). Some information is given about multiple exposures to chemicals only.

Description

Different interactions between chemicals are addition, antagonism and synergism.

Addition of chemicals is a non-interactive process. This means that in a chemical mixture the different chemicals do not affect the toxicity of each other. All chemicals individually contribute to the toxicity of the mixture and act in a similar way. The contribution of a chemical in a mixture depends on the dose of the chemical in the mixture.

Antagonism is the negative effect of chemicals on each others toxic action. The different chemicals have an inhibitor effect on each other.

Synergism is the positive effect of chemicals on each others toxic mechanism. The different chemicals have a strengthened effect on each other

Methods can be based on determine the hazard of each individual component in a mixture (component based methods) or determine the hazard of the whole mixture. For component based methods it’s necessary to determine the combination of the chemical mixture, the different target organs and mode of action (MOA) of the individual chemicals.

Component based methods include:

• Hazard index (HI), toxicity equivalent factors (TEF), relative potency factors (RPF) - all applicable for chemicals which do have the same toxic effect and toxic mode of action.
• Response addition - applicable for chemicals with different toxic effect and different mode of action
• cumulative RPF - applicable for a mixture which contains chemicals with the same toxic effect, but different mode of action)
• Binary weight of evidence (BINWOE) - applicable for interaction between chemicals. For using this method the interaction between chemicals in a mixture should be known.

Whole mixtures methods include:

• Cancer slope factors - the dose-response of different chemicals in a mixture is measured (the risk of developing a tumour (response) after exposure to a chemical mixture (dose) is determined)
• reference dose and reference concentration - estimate of the daily exposure of a human population to a chemical mixture at which no health effect will occur
• effect-directed analysis - determine which chemical or complex of chemicals have a biological effect
• pattern recognition techniques and multivariate regression models - determine whole mixtures and there possible health effect
• toxicogenomic - effect of a wide variety of chemicals in a mixture on molecular level can be detected

Information about non-chemicals not yet available

References

To be included (if wanted?) - ask Anne

Definition

Information limited to chemicals, which is not useful for this study. I (Anne) will try to find out if there is any info on combined exposure to noise and air pollution.

Causality

Data

Formula

Unit

Result

For multiple exposures to noise and air pollution (as in case study) no information/ methods have been found yet.

Category:Kuopio workshop