[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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