Food Science and Technology

The Acceptable Daily Intake (ADI) The Acceptable Daily Intake (ADI) procedure has been used to calculate permissible chronic exposure levels for humans based on non-carcinogenic effects. The ADI is the amount of a chemical to which a person can be exposed each day for a long time (usually lifetime) without suffering harmful effects. It is determined by applying safety factors (to account for the uncertainty in the data) to the highest dose in human or animal studies which has been demonstrated not to cause toxicity (NOAEL).  The EPA has slightly modified the ADI approach and calculates a Reference Dose (RfD) as the acceptable safety level for chronic non-carcinogenic and developmental effects. Similarly, the ATSDR calculates Minimal Risk Levels (MRLs) for noncancer endpoints. The critical toxic effect used in the calculation of an ADI, RfD, or MRL is the serious adverse effect which occurs at the lowest exposure level. It may range from lethality to minor toxic effects. It ...

In toxicology,  point of departure (POD)  is defined as the point on a toxicological dose-response curve established from experimental data or observational data generally corresponding to an estimated low effect level or no effect level. It marks the beginning of extrapolation to toxicological reference dose  RfD  or reference concentration  RfC . US EPA defines RfD or RfC as follows.  [ Note : In EU, RfD may be called  derived no-effect level (DNEL) .] Reference dose (RfD) : An estimate (with uncertainty spanning perhaps an order of magnitude) of a daily oral or dermal exposure to the human population (including sensitive subgroups) that is likely to be without an appreciable risk of deleterious effects during a lifetime. Its unit is usually  mg/kg bw/day  or  mg/kg . Reference concentration (RfC) : An estimate (with uncertainty spanning perhaps an order of magnitude) of a continuous inhalation exposure to the human...

Dose-Response Assessment The dose-response assessment step of the risk assessment process quantitates the hazards that were identified in the previous step. It determines the relationship between dose and incidence of effects in humans. There are normally two major extrapolations required: From high experimental doses to low environmental doses. From animal doses to human doses. The procedures used to extrapolate from high to low doses are different for assessing carcinogenic effects and noncarcinogenic effects: Carcinogenic effects  in general are not considered to have a threshold and mathematical models are generally used to provide estimates of carcinogenic risk at very low dose levels. Noncarcinogenic effects   (for example neurotoxicity)  are considered to have dose thresholds below which the effect does not occur. The lowest dose with an effect in animal or human studies is divided by safety factors to provide a margin of safety. Figure 1. D...

What is Toxicokinetics? Toxicokinetics Defined Toxicokinetics  is essentially the study of "how a substance gets into the body and what happens to it in the body." Before this term was used, the study of the kinetics (movement) of chemicals was originally conducted with pharmaceuticals and the term pharmacokinetics became commonly used. Similarly, toxicology studies were initially conducted with drugs. Toxicokinetics deals with what the body does with a drug when given a relatively high dose relative to the therapeutic dose. Read more about   differences between pharmacokinetics and toxicokinetics . Processes Four processes are involved in toxicokinetics: Absorption  — the substance enters the body. Distribution  — the substance moves from the site of entry to other areas of the body. Biotransformation  — the body changes (transforms) the substance into new chemicals (metabolites). Excretion  — the substance or its metabolites leave th...