Intake Limit Value
To evaluate humans' health risks it is common practice of risk assessors to compare the intake with a health based limit value (HBGV), like the ADI (Acceptable Daily Intake) and the ARfD (Acute Reference Dose) of chemical substances. A HBGV is the "Non Observed Adverse Effect Level" (NOAEL) of these substances for humans. Exceeding the HBGV is then to be considered a potential health risk for the consumer. You can read more about this in this portal under HBGVs and BMDLs.
For BMDLs the approach is slightly different. A BMDL is a limit value for a certain effect in experimental animals such as rats or mice, dogs or monkeys, or humans. A Margin of Exposure is needed to overcome the variations between human consumers or for differences with experimental animals. For BMDLs there is a health risk when the ratio of the intake and the BMDL is less than the MoE. This means that the critical intake level equals the BMDL ÷ MoE.
Based on the above it is possible to derive an "Intake Limit Value" (ILV). This limit value is the dose level above which the intake is becoming a health risk.
(1) HBGVs have a MoE of 1, and the ILV equals the HBGV.
(2) For BMDLs the ILV equals the BMDL ÷ MoE. As an example: the ILV is 0.55 ug per kg per day for a substance with a BMDL10 of 55 ug per kg per day with a MoE of 100.
(3) When using a slope factor for carcinogenic substances the ILV is to be calculated in a somewhat different manner. Its ILV for a lifetime cancer risk is 0.0001 (1 case per 10,000) ÷ slope factor . The unit of the slope factor is [mg per kg body weight per day]-1 giving an ILV in mg per kg per day. As an example: for a genotoxic compound with a slope factor of 0.055 [mg per kg per day]-1 the ILV is 0.0018 (0.0001 ÷ 0.055) mg per kg per day. And, intake levels greater than 0.0018 mg per kg per day have a cancer risk of more than 1 person per 10,000. For other cancer risks such as 1 case in 1,000,000 consumers one needs to adjust the calculation accordingly.
Limit of Rejection
According to article 14 of EU-Regulation 178 of 2002 (also known as the General Food Law or GFL), the official control authorities can reject food and feed if it is "unsafe" for the consumer. To know whether food or feed is unsafe, an exposure assessment of the situation is needed. For this risk assessors use a procedure where intake of a chemical is compared with a permissible exposure level as described previously.
Based on this approach it is possible to calculate the concentration in food where the HBGV or MoE of a BMDL is just exceeded. This is called the Limit of Rejection (LoR). It means that all samples with a concentration above the LoR are to be considered unsafe, and that the food and feed can be rejected by the official control authorities according to article 14. So the LoR can be used as a control value to reject contaminated food or feed. The EAST tools in this portal calculates the LoR when evaluating a concentration of a chemical in a food commodity. Beware that a LoR is not to be used in the EU for substances for which a MRL or ML exists, as the MRL and ML are legal standards whereas the LoR is just a guidance value.
To calculate the LoR, one can use the following formula. Take care of the correct units.
Note that the number for the body weight of the consumer can be ignored when the consumption quantity Q is provided in kg commodity per kg body weight per day.
The Maximum Consumption Quantity
A similar type of entity like the LoR is the Maximum Consumption Quantity (MaCQ). This is the amount of food or feed to be ingested to exceed the ILV for a given concentration of the chemical.
This number can be used for a semi-quantitative exposure assessment. If the MaCQ is a very low value, e.g. 1 gram, for a commonly available food commodity (e.g. staple food), then it can be assumed that exposure poses a health risk for consumers without knowing the actual food ingestion quantity. At the same time it can be assumed that there is no exposure risk if the MaCQ is extremely large, e.g. more than 1 kilogram for most foods. Besides the value can be used if the contamination is only found in a limited quantity (for example in one bottle or tin). The EAST tool in this portal will calculate the MaCQ when you are evaluating a chemical in a food commodity.
To calculate the MaCQ, one can use the following formula. Take care of the correct units.