Methods to track transport of particles in the environment and in the body

Yes, there
has been considerable work done in the modeling of the migration/translocation
of radioactive materials, both gases and particulate matter, in the environment
and in the human body. The methods that apply to the environmental transport of
materials involve pathway analyses that trace movement through various media to
a desired endpoint. Often the endpoint is a human being. The mathematical
models that apply to transport in the external environment are different from
the models that apply to intake and distribution of the same radioactive
species in the human body, although some conceptual aspects are similar. We are
not able here to provide details about the mathematical models involved, but I
will try to provide some information to assist you.

Environmental
transport models include such elements as atmospheric dispersion, transport in
surface and groundwater, transfer to soil and vegetation, and uptake by land and
sea/freshwater animals, including man. 
The models can be quite complicated and some require rather
sophisticated mathematics to describe and solve the transport equations.

One of the
better-known and useful references in this regard is a book edited by John Till
and H. Robert Meyer, Radiological Assessment: A Textbook on
Environmental Dose Analysis, published in 1983 as NUREG/CR-3332 for the U.S.
Nuclear Regulatory Commission. This large volume is available online through this NRC link. A
revised edition of this reference is available as a book by John Till and Helen
Grogan, Radiological Risk Assessment and Environmental Analysis, Oxford, 2008.
It is available on Amazon.com
as well as other places.

The RESRAD group of computer codes,
available free through Argonne National Laboratory, is extremely popular and
widely used for assessing dose consequences associated with the transport of radioactive
materials in environmental media and in specialized situations. Perhaps the
major application of RESRAD codes has been in assessing the dose impacts of residual ground
and/or building contamination at sites undergoing decommissioning activities.

If you are a
member of the Health Physics Society, you can find additional related resources
on the Members Only page; click on the Toolbox for Health Physicists, and look
at the listings under Atmospheric Dispersion and Decontamination and
Decommissioning. There are many other sources of information on this topic and
much information and assistance available through government agencies, such as the Environmental Protection Agency (EPA).

Most of the best
known and widely used work related to intake, uptake, distribution, retention,
and excretion of radioactive materials in the human body has been published by
the International Commission on Radiological
Protection (ICRP). The work includes consideration of intakes of
particulate activity (as well as gases) primarily through inhalation and
ingestion. Regulations, specifying intake limits for radionuclides in current
use by the U.S. Nuclear Regulatory Commission (NRC) or agreement state
licensees in the United States, are based on results obtained from internal
dosimetry models described in ICRP Publication 30, Limits of Intakes of
Radionuclides by Workers (published in four parts and supplements from 1972 to
1978).

In later
years, the ICRP updated its recommendations and made changes to many of the
intake and metabolic models that had been in use. The respiratory tract model
became considerably more sophisticated than that used in generating ICRP-30
results, and metabolic models that had earlier included primarily one-way
transport through tissue compartments in the body were modified to allow
recycling of material between blood and organs.

The major relevant
ICRP publications that document the ICRP efforts and results are ICRP Publications
61, 66, 67, 68, 69, 71, and 72, all of which you can find described among the publications listed on the ICRP Web
site.

There are
naturally many other sources of information about the transport of radioactive
material within the human body. The EPA and the NRC have published various
documents relating to internal dosimetry and some of the modeling
considerations. You can search for some of these online. Again, if you have
access to the Health Physics Toolbox, you can find some useful Web pages by
searching the listings under Dosimetry – Internal Dosimetry. 

I hope this
is helpful. Good luck.

George
Chabot,
PhD, CHP