Safety level for who?  The US government has set maximum levels for plastic containers.

Do you mean if there is no human tox data?  I do note that phthalates are becoming of particular concern as leachables.  The actual permissible daily exposure of these would also depend on the total daily intake and route of administration of your pharmaceutical product.

There are too many variables in the question to be able to answer it.  Permitted levels of phthalates for human exposure seem to vary from country to country and often only apply to specific items (like the limits for toys, plastic containers and things like medical tubing and bags for using with a drip line).  If you look up the MSDS for each compound there will be some information there but that is not necessarily helpful when you are looking at a pharmaceutical product.  You would need to hunt around for information (if there is any) on the limits allowed for phthalates in a specific type of pharmaceutical - if this exists it will give different levels for an external cream to something you ingest.  In the USA there is increasing concern about the cumulative effects of phthalates as they are so ubiquitous in the environment and I don't think there is any agreement on how to assess a 'safe' level for this or how you would enforce it.  You also have a problem in that you don't know what proportion of your phthalates will leach, evaporate etc. and how much of that will get into the user of the product.  That would require testing and it would be hard to design a suitable experiment because of the issues mentioned above and the different levels of exposure people experience in their daily lives.  The only truly safe level of phthalates in pharmaceuticals is zero, or as near to that as you can get.

As suggested by Valerie, you need to collect toxicological data on phthalates and based on which you may derive a Acceptable Daily Intake (ADI). The next step depends on for what purpose the concerned product is intended to be used. Based on the actual use condition of the product under question, you may determine how much of the extractable is exposed by the individual patient (or consumer). If the exposure is higher than the ADI, there may be a potential health risk. Conversely if the exposure is lower than the ADI, there is negligible risk. It is also possible that depending on the product, you may refine the derived ADI and the limit may be increased on a case by case basis

Thank you all for your nice suggestion.

But, needs more help from you guys.....

I will give example of my study...

one of selected product for E&L is Antibiotic parental (I.V.) preparation having 100ml liquid.

I have gone through optimized extraction procedure from product and analyzed... finally calculated the total amount of phthalates presented in whole formulation against blank. Out of four, DEHP was dominantly found from sample and that was approx. 80 microgram/formulation (average of 3 times). 

So, What I could conclude from this in relation to safety level for human exposure. 

80 ug/dosage seems high to me.  Take the advice above if you wish to obtain a PhD and issue a dissertation on safety levels.  It probably has never been done before!

However, I would start a process of mitigation.  Look at your manufacturing process and eliminate and substitute those plastics that would use phthalates in their manufacture.  I would suspect the fermentation bottles are single use systems which typically have potentially the highest concentration.

Then retest your dosage.  It should have a much lower concentration.

Thanks

 Thank you, Toske Kryeziu for informative note.

I have already go through this but If you could extrapolate to my experimental result as mentioned above discussion then it will be more useful.