[Pharmwaste] Re: Pharmwaste Digest, Vol 47, Issue 2
randsney at comcast.net
randsney at comcast.net
Mon Sep 14 16:43:34 EDT 2009
FYI on analytical extraction methods.
Ronald E. Ney, Jr., Ph.D.
September 14, 2009
Are chemical extraction methods valid?
Are chemical extraction methods valid to extract chemicals from soil,
sediment, sewage sludge, plants and animals? These methods may be solid
waste (SW) methods or pesticide methods used to extract chemicals and
degradation products from soil, sediment, sewage sludge, plants and animals.
Do the methods extract residues that have a high Koc (organic carbon
partition coefficient) value in soil or a high Kow (octanol water partition
coefficient) value in fat tissue? If you want to know these values read my
book Fate and Transport of Organic Chemicals in the Environment (third
edition). Bottom line answer is almost all the methods have not been
validated. Fortifying a matrix and extracting does not prove that an
extraction procedure will work for chemicals aged in the matrix over time
(i.e. 30, 60 & 120 days).
By validation, I mean using procedures like those that I wrote in 40 CFR §
158:290 and § 158.1300 Subpart N, which FIFRA requires by aging of
pesticides in soil to discern bound residues, extraction of parent and
degradates and analytical efficiency. These data requirements were started
in the USDA around 1967 because radiotracer studies for petition for
tolerances indicated pesticide residues were not being totally extracted and
where showing up in crops (rotational crops) when they shouldn't have been.
This does not mean that those residues determined by other methods were
incorrect. Please remember that residues under FIFRA include parent and
degradation products.
a.. It means that the total amount or residues extracted is questionable
and that there may have been a lot more not extracted.
b.. It means that many other chemicals may not been have been extracted
and thus not determined.
c.. It means that there may be chemical residues not extracted, which
could be available for plant and animal uptake.
d.. It means that a hazard assessment cannot be accurate without knowing
total exposure via inhalation, absorption and ingestion of total residues
(extractable and un-extractable).
Here are examples of some questions that I have asked concerning residues in
sediment, plants, sewage sludge, water, etc.
1. Do the extraction procedures/methods extract residues bound in the
organic matter of soil or sediment?
2. Do the extraction procedures/methods extract residues bound in fat
in animals?
3. Do the extraction procedures/methods provide a material balance for
residues in each of the following matrices soil, plants and animals, that is
total residues of parent, degradates, and bound (non-extractable residues)
residues?
4. Where radiotracer methods used to obtain data as question in three
above?
So what could all this mean?
1.. It could mean that all the residues (parent and degradates) are not
determined in the food we eat.
2.. It could mean that all the residues (parent and degradates) are not
determined in soil, animals, sediment, and sewage sludge and residues are
much higher in environmental matrixes than extracted and determined.
3.. It means that exposure may be greater than expected.
Many may say exposure to chemicals and/or biologicals in consumer products,
in the environment, etc. is so small there is little chance of risk. While
this may be true in many cases, safety cannot be judged on one chemical or
one biological alone. Humans and other animals are a mixture of chemicals
and biologicals, and we take in hundreds of different chemicals and
biologicals a year. How safe are these chemicals and degradates
(pesticides, hormones, metals, etc.) and biologicals when the aggregate,
synergistic, antagonistic, co-metabolism and co-biometabolism effects are
never mentioned or studied to any extent, if at all and, they are not used
in risk assessments? In other words, the total picture is never known or
considered for hazards to adults, child endangerment and environmental
safety when it should be required.
The bottom line is that USEPA, FDA and other enforcement methods do not
account for total residues of parent chemical and their degradation
products. Safety cannot be determined.
Below are parts of some responses that I have received on extraction
methodology to support what I have said above.
1. USEPA does not claim validity to their methods.
Quoted in part from USEPA Internet site.
Environmental Chemistry Methods (ECM)
Environmental chemistry methods for soil and water are used to determine the
fate of pesticides in the environment. The methods identify and quantify the
pesticide residue of interest, determining the total concentration of
pesticides, including the extractable parent compound and significant
metabolites and degradates (break-down products).
EPA makes no claim of validity by posting these methods, but recognizes that
the methods may be of some utility to state, tribal, and local authorities.
Residue Analytical Methods (RAM)
Residue analytical methods for food, feed, and animal commodities identify
and quantify the pesticide residue of interest, determining the total toxic
residue of the pesticide regulated by the tolerance (maximum legal residue
level), including significant metabolites and degradates (break-down
products).
While most of the methods perform satisfactorily, some may have
deficiencies.
EPA makes no claim of validity by posting these methods, but recognizes that
they may be of some utility to state, tribal, and local authorities.
From: <Riggs.Rebecca at epamail.epa.gov>
To: <randsney at comcast.net>
Cc: <Ferrario.Joseph at epamail.epa.gov>
Sent: Wednesday, June 10, 2009 3:37 PM
Subject: EPA Mothod Validity Statement
The following is only a part of the response.
"The methods are submitted to OPP as part of the registration package, with
the methods coming from various sources. Once received, EPA places these
methods on the Web site without validating them."
2. USEPA on solid waste methods
Dear Ronald Ney,
Thank you for your follow-up inquiry.
"The majority of SW-846 methods are validated and peer reviewed using the
statistical validation model from the American Organization of Analytical
Chemists (AOAC) or some variation of this model which is an official
validation approach for analytical methods.."
"Regarding your comentary to the following statement: "Furthermore, most
extraction and analytical protocols assume that the detected concentration
represents the total for a given compound, so it would be uncommon to
perform a material balance with the non-extracted concentration since this
is an unknown value.."
The MICE Service is operated by Science Applications International
Corporation (SAIC) under contract to the USEPA Office of Solid Waste.
3. USEPA on solid waste methods
Thank you for your inquiry.
"The SW-846 methods were validated using real world matrices that are
appropriate for RCRA waste testing and characterization. Typically, the
material to be tested is spiked with a certified concentration of the
desired target analytes along with surrogates that are similar in chemical
composition to assess the extraction efficiency. Given this, numerous
holding time studies have been performed to evaluate the target analyte
stability, however, we are not aware of any such studies that have used
radio labeled parent compound to asses the possible degradation.."
The MICE Service is operated by Science Applications International
Corporation (SAIC) under contract to the USEPA Office of Solid Waste.
4.Response from USGS
Ron,
No, these methods have not been "validated" using radiotracers. There
generally aren't available radiotracers for the large list of analytes we
determine. We sometimes have difficulty getting regular standards for some
analytes, especially degradates.
Dr. Ney,
5. From the Florida Dept. of Environmental Protection
A message from you to our Office of Citizen Services was forwarded to me for
a response (your message is pasted below). I appreciate your concern
regarding the extraction efficacy of SW-846 methods. It would take an
exhaustive search of the scientific literature to determine definitive
answers to the questions you pose but I am not aware of such studies using a
wide range of radio-labeled compounds. EPA does not generally require the
use of radio-labeled compounds in validation studies during SW-846 method
development. Furthermore, our Department does not require laboratories to
use radio-labeled compounds during method validation exercises.
6. USEPA response
1. If SW extraction procedures were used, how where the extraction
procedures validated? Extraction QC includes duplicates, matrix spikes,
matrix spike duplicates, blanks and Laboratory Control Samples.
2. How do you know that all water insoluble residues (those residues bound
in organic matter) were extracted from sediment? We do not know nor do we
want them. Most EPA methods are intended to find pollutants that are
readily available to migrate in the environment. EPA methods generally do
not find insoluble anything.
3. Was a material balance established for all residues in sediment and
animals and if so how? Probably not. GLNPO modeling is usually concerned
with air, water, sediment material balances. I have not seen animals
included.
Quality Assurance for Region 5 EPA, Chicago Regional Laboratory
7. Environmental Chemistry Branch, USEPA/ORD/NERL-ESD
Chemicals PCPP's in water containing suspended sediment.
1. How do you know that you can extract the chemicals that have been aged
for months in a water matrices containing suspended sediment and not just
fortifying and extracting? As you know, this is a classic question that
originated with determining the fate of pesticides in the environment. The
question of residues weathered into matrices and not
yielding to extraction is always a possibility. We have recently applied a
method that we developed for sewage biosolids to sediments (that we had
collected and dried), and we did extract macrolide antibiotics from the
unfortified sediment samples. But it's not possible to determine the
actual recovery efficiencies.
2. How do you know if degradation of parent chemical has or has not
occurred, and that degradates are extracted and determined? We don't. With
pharmaceuticals, some attention is just beginning to be placed on
degradates/metabolites especially those that are bioactive or that have
longer half-lives and therefore serve as better indicators of occurrence.
3. Where any of the test validated using radiotracer parent
chemical(s) aged in the matrices over time (aged for up to six months prior
to extracting) like that which would occur under environmental conditions?
We're not aware of anyone who has performed radiotracer studies for
weathered residues (as has been done with pesticides).
4. Has a material balance and total accountability for residues (parent and
degradates) aged in any media been carried out? Definitely not.
Chemicals PCPP's from wastewater systems.
1. How do you know that you can extract the chemicals that have gone through
a wastewater treatment system and not from just fortifying a matrices and
extracting? Because we find PPCPs in the wastewater samples. It's the
efficiency of extraction of endogenous residues that's unknown.
2. How do you know if degradation of parent chemical has or has not
occurred, and that degradates are extracted and determined? We don't.
3. Where any of the test validated using radiotracer parent
chemical(s) aged in the matrices over time (aged for up to six months prior
to extracting) like that which would occur under environmental conditions?
Not that I'm aware of.
4. Has a material balance and total accountability for residues (parent and
degradates) aged in any media been carried out? Not that I'm aware of.
Did you consider or do you plan to consider any of the
following:
1. Presence of dioxin(s) from Triclosan? Not at this time.
2. Synergistic effects? We are an exposure lab. Tox studies reside with the
National Health and Environmental Effects Research Lab. In general, synergy
is extremely difficult to prove. Most studies support concentration
additivity. Synergy is definitely a possibility, however, with exposure to
stressors having wildly disparate MOAs. The inhibition of efflux pumps in
aquatic organisms is an example scenario whereby the toxicity of other
chemical stressors could be greatly enhanced.
3. Additive effects?
4. Antagonistic? Some thinking on these questions is presented in the paper
here:
http://epa.gov/nerlesd1/chemistry/pharma/images/emerging_contaminants.pdf
8. Pesticide extraction procedures
Radiotracer chemicals are not used to prove total extraction of residues.
Pesticides that are not extractable or recoverable are not detected and are
not accounted for. If they cannot be detected, they cannot be accounted for.
Center for Food Safety and Applied Nutrition
Food and Drug Administration
----- Original Message -----
From: <pharmwaste-request at lists.dep.state.fl.us>
To: <pharmwaste at lists.dep.state.fl.us>
Sent: Monday, September 14, 2009 11:14 AM
Subject: Pharmwaste Digest, Vol 47, Issue 2
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