Hello Nagarjuna,

OEL is used for determine limits for workers that are in contact with a certain product.

With PDE the toxicological limit for patients that ingest the product can be calculated. This value prevents cross-contamination.

I am not expert on calculating PDEs but as far as I know, for calculating PDE product values, a value of NOAEL (no-observed-adverse-effect level) is needed.

There is a rule of thumb in which you can estimate that for a certain value of OEL you can expect certain value of PDE, but nothing especific for your product.

I hope that this little explanation helps you.

Rocio Ferrera Thanks for the reply.

Actually i am looking for an answer which will clarifies te below

Is it possible to calculate PDE value with available OEL of the same compound?

Thanks

Nagarjuna

For calculating both values is NOAEL used.

This article may help you

http://www.pharmtech.com/understanding-containment

Sorry for not answering quite accurate.

Rocio Ferrera Thank you very much for the response and the article.

Hi Nagarjuna,

The OEL is actually calculated from an ADE so, yes, it's possible to back calculate from an OEL to an ADE. The ADE is the Acceptable Daily Exposure by some route which is usually for exposure through inhalation but OELs can also be calculated for the dermal route for setting limits for contact exposure (e.g., hands).

OELs for inhalation are usually calculated as ADE/10 to get an hourly exposure to the compound since a typical worker inhales 10 m^3 of air in an 8 hour shift. So multiplying by 10 gets you back to the ADE.

But.... there are some things you also need to understand.

ADEs usually vary based on the route of exposure. So inhalation may have a 100% bioavailability and dermal may only be 5% so an additional adjustment may need to be made after multiplying by 10 to get back to the ADE by inhalation route if you are looking for the ADE for some other route (injection, ocular, oral, etc.)

FYI, there is a new ASTM "Standard Guide for the Derivation of Health Based Exposure Limits (HBELs)" that will be published and available in about a week. (HBEL is the term the EMA has begun using for ADEs/PDEs). This standard goes over all the steps and adjustment factors used in the derivation of HBELs and can be also used in the derivation of OELs - although the Standard is focused on patient exposure and not worker exposure. I am the Technical Contact for this Standard so you can follow-up with me if you are interested in this document.

Also, consider joining the Linked in Discussion group "ASTM Standard E3106: Science-Based and Risk-Based Cleaning Process Development and Validation" since all of the toxicologists that wrote the new HBEL Standard are members and can better answer your questions than me (I'm not a toxicologist).

https://www.linkedin.com/groups/12100534/

I hope this was helpful.

Best regards,

Andy

Andrew Walsh Thanks for the clarification.

I am very much intersted in the new ASTM "Standard Guide for the Derivation of Health Based Exposure Limits (HBELs)". So kindly intimate me whenever the Standard published.

Thanks

In the following , you will find :10 myths regarding PDEs, ADEs, and OELs:

http://potentcompoundsafety.com/2015/01/ema-dedicated-facilities-pde-ade-oel.html

Thank you Maged G. Bin-Saad