×
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

Log In

Come Join Us!

Are you an
Engineering professional?
Join Eng-Tips Forums!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

Students Click Here

PCt50, HCt50, LCt50, LD50, LC50

PCt50, HCt50, LCt50, LD50, LC50

PCt50, HCt50, LCt50, LD50, LC50

(OP)
Good day, forum

Can anyone share a worth source for PCt50, HCt50, LCt50, LD50, LC50? What does it exactly mean? Is there some database of threshold values for chemicals? Which codes and practices are worth to be implemented?

RE: PCt50, HCt50, LCt50, LD50, LC50

LD50 and LC50 are a standard measure of the toxicity of the surrounding medium that will kill half of the sample population of a specific test-animal in a specified period through exposure via inhalation (respiration). LC50 is measured in micrograms (or milligrams) of the material per liter, or parts per million (ppm), of air or water; lower the amount, more toxic the material. Used in the comparison of toxicities, LC50 values cannot be directly extrapolated from one specie to the other or to humans. Also called median lethal concentration or population critical concentration 50. Written also as LC50.

In toxicology and eco-toxicology, dose descriptor is the term used to identify the relationship between a specific effect of a chemical substance and the dose at which it takes place. The dose descriptors will be used later for deriving the no-effect threshold levels for human health (i.e, DNEL or reference dose RfD) and the environment (PNEC). Dose descriptors are determined in the toxicological studies on the hazards of the substance and are usually expressed as LC50, LD50, NOAEL, NOAEC, T25, BMD, EC50, NOEC, DT50, etc. They are used for GHS hazard classification and risk assessment.


dose descriptor

Reference Book

PCt50, HCt50, LCt50 don't appear to be related to LD50 and LC50:

LCt50: The amount of liquid chemical agent expected to kill 50 percent of a group of exposed, unprotected individuals.

PCt50: Parasite clearance rate - the time which (malaria) parasite levels decline in a patient's blood after treatment

HCt50: Hematocrit levels are the percentage of packed red blood cells height inside a centrifuged blood tube.

Why are you asking about this terminology?

RE: PCt50, HCt50, LCt50, LD50, LC50

(OP)
It is hard to answer briefly. Recent revision of a local code in my country stated that "threshold dose" in exposed territory shall be evaluated and this parameter influences SIL, reliability level etc. and by this way CAPEX. The problem is with "threshold dose" - there is no clear definition what exactly it means.

There is no an exact system for toxicity in my country. Some local codes exist but they are contradictory. Symbols LC50, PCt50 etc. are used so I considered that these local codes are some bad translation of international documents. There are some "threshold doses" of toxic chemicals:
PCt50 - 50% threshold dose in mg*min/m3
HCt50 - 50% threshold dose in mg*min/m3
LCt50 - 50% lethal dose in mg*min/m3
LC50 - 50% lethal dose in mg/m3
LD50 - 50% lethal dose in mg/kg

As you can see many figures can be implemented as "threshold dose" and by this way CAPEX.

Moreover there is no a reliable database of threshold doses in my country.

Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

Reply To This Thread

Posting in the Eng-Tips forums is a member-only feature.

Click Here to join Eng-Tips and talk with other members! Already a Member? Login


Resources

eBook - Functional Prototyping Using Metal 3D Printing
Functional prototypes are a key step in product development – they give engineers a chance to test new ideas and designs while also revealing how the product will stand up to real-world use. And when it comes to functional prototypes, 3D printing is rewriting the rules of what’s possible. Download Now

Close Box

Join Eng-Tips® Today!

Join your peers on the Internet's largest technical engineering professional community.
It's easy to join and it's free.

Here's Why Members Love Eng-Tips Forums:

Register now while it's still free!

Already a member? Close this window and log in.

Join Us             Close