The NOAEL project

Endpoints to inspect and substance’s classification

The NOAEL-project follows SCCS guidelines.
To fully characterize the toxicological profile of the substance of interest 10 endpoints should be inspected:

• Irritation and corrosivity
• Sensitization
• Dermic/percutaneous absorption
• Repeated dose toxicity
• Mutagenicity/Genotoxicity
• Carcinogenicity
• Reproductive toxicity
• Toxicokinetic
• Photo-toxicity
• Human data

If one or more of the principal endpoints (underlined in the list above) are missing, the substance’s profile will be classified as “Incomplete”. In this way we will be able to further look for missing endpoints, completing the profile.
It’s important to remember that a substance classified as “Incomplete” will always have at least one NOAEL: one should consider “Incomplete” as “It does not have all the required NOAEL”.
If all the enpoinds are inspected, the substance will be classified as “NOAEL”.
If the NOAEL is derived from a read-across study (meaning that is retrieved from a very similar ingredient), the substance will be classified as “NOAEL from read-across”.
Occasionally dermal absorption could be available in the datasheet, the classifications as “NOAEL + SED” is no longer in use, so the user should carefully inspect the “Chemo-physical” section of the datasheet.

In some cases, the cosmetic ingredient is listed in the Annexes; in this situation we decided to use the same classification and restriction of SCCS, but we also decided to include the NOAEL (if available): the reason is that some restrictions are strictly related to some cosmetic product, therefore a NOAEL could be useful if the user employs the same ingredient in other types of cosmetics. This substance will be classified as “In the Annexes”.
If we weren’t able to find a NOAEL, the substance will be classified as “No test available” and will be excluded from the excel file listing all the ingredients in the database.

To sum up, according to our classification each substance can have the following states:

Only in the red cases a NOAEL is missing from the datasheet.

A NOAEl can be retrieved only from certain studies: repeated dose toxicity, cancerogenicity, teratogenicity and reproductive toxicity. Results from other endpoints are reported in the datasheet for completeness.
According to the SCCS, a NOAEl from a subacute study must be divided for a factor of 3 because the standard minimal duration is 90 days. In all the NOAEL-project datasheets the NOAEL is already divided by this factor if necessary.

Criteria for choosing a NOAEL

The final NOAEL has to be the lowest regardless of the animal species used or the toxicity test employed. In the “Notes” section of each datasheet all the considerations that drove us to our conclusion are summarized. If the interpretation of the source is very easy to understand, there will not be a detailed discussion but only a link pointing to the source’s details.

In the case we have three NOAEL as showed in the table above, a common mistake is to consider the NOAAEL from inhalation if the cosmetic ingredient is part of a spray formulation. The right NAOEL to choose is the lowest among the three, that is the one from the reproductive toxicity test.
Being a database based on single substances, their toxicity evaluation will be totally unrelated from the final cosmetic product: for example, if a given ingredient is employed in a spray, we should take into account all the subministration routes, not only the inhalation one (oral, gavage etc...).
The final cosmetic product only affects the SED (and therefore MOS) calculation.

Single dose experiments

To get a NOAEL is mandatory to test several doses of one chemical. This way it will be possible to identify a toxicity threshold defining LOAEL and/or NOAEL.
Test using a single dose for testing a given toxicity endpoint are unable to identify thresholds. The lack of toxic effects following a single administration is not so informative, especially if the dose is very low. Even in the case some adverse effects would be observed, the single dose does not allow to consider that value as a LOAEL (meaning that there could be also smaller doses causing adverse effects).
By giving these values the same importance of a NOAEL/LOAEL retrieved from multiple dose test, it is possible to largely over/underestimate the real NOAEL/LOAEL. For this reason we decided not to consider these values unless no other test has been found. Even in this case in the “Notes” section it will be reported that this data come from a single dose experiment and that more reliable data will replace it when found.
In the case only a LOAEL from a single dose experiment is available, we don’t calculate the corresponding NOAEL unless the authors of the study or the commission approve it.

Experiments’ reliability

NOAELs from a more recent study doesn’t necessarily mean that this must be preferred to older ones. A very important parameter is represented by the range of dose tested.
Ideally the substance is administered for 14 days at dose very large and spanning from each other: the scope of this test is indeed to explore the dose range that will be used in the repeated dose tests (subacute, subchronic and chronic). Range with extremes very distant from each other and regularly spanned allow the identification of a NOAEL way more precise rather than range with doses spanned less regularly.

Example: A very recent study on Sorbic acid employing a very big dose range showed a NOAEL of 1.5% and 1% in rats and mice respectively. An older study with a shorter range of doses employed showed a NOAEL of 5% in both the animals. The first study tested the substance at 1.5% and then at a concentration bigger than 5%, which in turn showed clear adverse effects. In this case we didn’t considered the older study as replaced by the newer one since they used the same animal models and the dose range didn’t overlap¹.

Bigliography

1 Reports of the Scientific Committee for Food (Thirty-fifth series) pag. 19 (1996) 

Consistency with OECD guidelines and GLP

According to SCCS all the studies taken into consideration should follow Good Laboratory Practice (GLP) and OECD guidelines. Unfortunately great part of the sources doesn’t have such detailed information. A study that follows these guidelines represents undoubtedly a very reliable source of data. Each NOAEL-project’s datasheet have a field relative to this guideline.

Weight of evidence (Woe) for choosing a NOAEL

SCCS states that for correctly choosing a NOAEL a “weight of evidence” approach should be used. In few words that means to evaluate all the studies and to consider their details in order to create the most complete toxicological profile. We can summarize three different cases accordingly to ECHA:

• Case 1: No reliable study regarding substance’s toxicity. Use of studies not fully reliable with detailed description of employed methodologies.
• Case 2: One reliable study. The study is considered as a key-studyLo studio è considerato chiave; detailed description of employed methodologies is mandatory
• Case 3: More than one reliable study. If there is one key-study and other support informations, a detalied description of the key-study and a generic one of the additional documents are needed.

In the case wen have more than one reliable informations distributed in different studies (for example toxicological data retrieved from different animal models or from different tests) or in the case there is some conflict between them, a detailed description of all these studies is required.

The NOAEL-project is a fee for service. All the money are used to form and pay specialized personnel whose job is to add toxicological data to the database.
You can join the project by visiting this address

There is only one type of annual subscription:

• Access to the database without NOAEL request
  With this profile, the user will see every toxicological datasheet present in the database (both in the electronic and pdf version) from the moment of subscription to the next year.
  The user with this profile will be able to download the excel file for the MOS and SED calculation but not to commit a toxicological datasheet for a substance of personal interest

In the case we have funds to pay a person in order to search and insert NOAELs, registered users may send an excel file with maximum 20 ingredients of interest to infoATnoaelproject.it. We don't ensure we will be able to find all the NOAELs listed, however this is our way to improve the users' experience.
The excel file must have two columns showing INCI name and CAS number.