Difference between revisions of "ERF for tooth defects caused by TCDD (study-specific)"

Revision as of 12:23, 4 January 2008

<accesscontrol>seturi_group</accesscontrol>Study-specific E-R functions | Species-specific E-R functions | E-R function for children

Scope

Exposure-response functions for tooth defects caused by TCDD (study-specific) describes study-specific exposure-response functions for either enamel defects in molars or missing or smaller molars.

Definition

Data

Miettinen et al

Rat study

Alaluusua et al 2004

Seveso children study

Causality

List of parents:

• Exposure: TCDD concentration in body fat at the age of 0-14 days (in rats) or 0-5 years (children)
• Response: Probability of a missing third molar in rats, or an enamel lesion in children (studied in adulthood)

Unit

(ng/kg in fat)^-1

Formula

Measurement error models (MEM) and analogy extrapolation models (AEM) are used to derive estimates from the data. Measurement error models are used in situations where the actual item of interest is observed, but the measurement is imperfect. Analogy extrapolation models are used where the actual item of interest is not observed, but instead something similar to the item is used to make inferences about the item.

Exposure MEM

The exposure in the study is not known perfectly. Instead, we use measurements together with information about the error in the measurements to estimate the true exposure.

Response MEM

The response in the study is not known perfectly. Instead, we use measurements together with information about the error in the measurements to estimate the true response.

Selection MEM

The study is supposed to represent a base population, from which the studied individuals are a representative sample. However, there may be non-random selection of study individuals. This may cause bias. Therefore, information about selection bias is used to correct the E-R function.

Confounder MEM

The individuals are exposed to a large number of factors. There may be a systematic difference in other exposures in the exposed and non-exposed individuals. In epidemiology, these are called confounders. This MEM corrects the E-R function for the impacts of confounders.

Shape of curve near data

In each E-R study, some assumption was made about the shape of the E-R function. The same assumption is usually used to derive the result distribution for the E-R function. If the original exposure and response data is available, it is also possible to use another function.

Result