What Is Acceptable Daily Intake (ADI) and How to Calculate It
Little Pro on 2018-05-10
Acceptable daily intake (ADI) is a very import concept in chemical risk assessment. It is defined as the maximum amount of a chemical that can be ingested daily over a lifetime with no appreciable health risk. In this article, we will give you an introduction to ADI and show you how to calculate it.
Background
Humans can get exposed to various chemical substances via oral route (i.e, eating food, drinking groundwater, hand to mouth transfer). It is necessary to determine the maximum amount of a chemical that can be ingested on a daily basis to protect human health. That is why we need to calculate the Acceptable Daily Intake (ADI). For pesticide residues and food contaminants, ADI may also be called Tolerable Daily Intake (TDI). The US Environmental Protection Agency has replaced ADI and TDI with the single term, reference dose (RfD).
For food additives or food contact additives and other consumer risk assessment, we calculate the ADI first, compare it with estimated exposure levels to determine whether risks are accpetable.
Unit of ADI
The unit of ADI for a chemical substance is mg/kg bw/d or mg/kg bw. It means xxx mg per kg body weight per day or mg per kg body weight.
How to Calculate Acceptable Daily Intake (ADI)
The ADI is normally derived from the lowest no observed adverse effect level (NOAEL) determined from long-term animal (in vivo) studies. The ADI is calculated by applying a safety or uncertainty factor, which is commonly 100, to the NOAEL obtained from the most sensitive test species. The 100-fold safety factor is based on the need to take into account both the differences in species and differences in toxicokinetics and toxicodynamics.
- ADI = Long-term NOAEL (lowest value)/100
Example of ADI Calculation
Let's assume that we have obtained the following results for 1 chemical substance from long-term in vivo animal toxicology studies.
- Reproductive toxicity (rat): NOAEL = 50mg/kg bw/d
- Chronic toxicity (rat): NOAEL = 30mg/kg bw/d
- Carcinogenicity (mice): NOAEL = 10mg/kg bw/d
Then the ADI can be calculated as follows:
- ADI = 10mg/kg bw/d /100 = 0.1mg/kg bw/d
What this really means is that if a 60kg person intakes less than 6mg (60 * 0.1) of the substance per day, there should be no risk.
Reference
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