Task Group on Toxicology
Draft Meeting Summary
April 30, 2012
This document is part of the NSF International and Underwriters Laboratory process and is for NSF/UL
Committee uses only. It shall not be reproduced, or circulated, or quoted, in whole or in part, outside of
NSF/UL activities, except with the approval of NSF/UL.
Toxicology Task Group Chairs:
Ann Marie Gebhart (ToxServices LLC) & Al Hodgson (Berkeley Analytical).
NSF/UL Standards Development Staff:
Tim Corder (UL), Dan Ryan (UL), Maureen Sertich (NSF)
Participants:
Kari Allen (Steelcase), Kent Carlson (CPSC), Randy Carter (Steelcase), Wenhao Chen (California
Department of Public Health), Bill Freeman (Resilient Floor Covering Institute), John Hadley (Owens
Corning), Renee Hartsook (UL), Bill Hoffman (UL), Tom Lent (Healthy Building Network), Ann Mason
(American Chemistry Council), Stephany Mason (UL), Clarence Mow (Community Playthings), Reinhard
Oppl (Eurofins), Deborah Schoen (Health Canada), Denise Van Valkenburg (Herman Miller), & Stan
Wolfersberger (Owens Corning).
Agenda
1) Introduction: Ann Marie Gebhart, Co-Chair
2) Presentation by Deborah Schoen, Health Canada:
“Options for selection of inhalation Toxicology Reference Values (TRVs) for chronic exposure”
Filename: Inhalation TRVs for chronic exposure.pdf
3) Presentation by Kent Carlson, U.S. Consumer Product Safety Commission:
“Summary of available chronic exposure inhalation TRV programs and data”
Filename: Combination Prop 65, TAC, HAP, REL list.xlxs
4) Discussion: Pros and cons of different options
Discussion
M. Sertich took roll call and read the anti-trust statement.
Ann Marie Gebhart introduced speakers Deborah Schoen from Health Canada and Kent Carlson from the
U.S. Consumer Product Safety Commission.
Ann Marie Gebhart reminded the group that comments, questions, and suggestions can be submitted by
email to her and Al Hodgson.
The focus of this group is on chronic, non-cancer health-based endpoints. The chairs would like to
prepare a recommendation about the chronic, non-cancer endpoints before moving on to other endpoints
that might be considered.
Deborah Schoen was the first speaker and referred this file: Inhalation TRVs for Chronic Exposure (.pdf).
The document starts with the question: “What set of indoor air values should be adopted in a healthbased emissions standard?” The Indoor Air Program at Health Canada has asked what indoor air values
they should use from other programs to use for their program.
D. Schoen referred to TRVs, or toxicological reference values, a generic term that covers oral, dermal, or
inhalation exposure limits from various organizations. This group’s focus is on the inhalation exposure
limits for VOCs. TRVs can be acute, subchronic, or chronic. The focus of this group is chronic. TRVs can
also be used for cancer or non-cancer effects. An example of a TRV may be a reference concentration
from the U.S EPA, MRL from ATSDR, chronic REL from CalEPA or OEHHA. Health Canada calls them
“tolerable concentrations.”
An inhalation TRV for chronic exposure is defined in a similar way between the different programs. The
U.S. EPA definition for Chronic Reference Concentration (RfC) is included in the document referenced
above.
BMCL – Benchmark Concentration, Lower Limit of Confidence Interval
NOAEL – No Observable Adverse Effect Level
LOAEL – Lowest Observable Adverse Effect Level
There may be differences between organizations about what is considered chronic duration. Health
Canada looked at the following organizations for their review: OEHHA, U.S. EPA, ATSDR, WHO, and
Health Canada. Today’s discussion was limited to OEHHA, U.S. EPA, ATSDR, and WHO.
European databases like AgBB have LCIs (Lowest Concentration of Interest) and the French program
have guidelines for indoor air. These programs have been excluded from this discussion because they
use occupational exposures as a starting point which is a different from other programs.
“Overall OEHHA, US EPA, ATSDR, and the WHO use similar risk assessment approach, with some
differences in methodology; WHO is perhaps less consistent in their methodology from one chemical to
the next, as each chemical assessment has its own working group made up of international experts.
The draft assessment is externally peer reviewed in the case of OEHHA, US EPA, ATSDR. The WHO
assessment represents the consensus of experts from different organizations and once the working group
members are satisfied, there is no further peer review prior to publication. Some chemicals may be more
extensively peer reviewed than others (for example National Academy of Sciences review of certain US
EPA draft assessments).” This happened with TCE and formaldehyde.
These have expert peer reviews; the U.S. EPA and OEHHA reviews have extensive public consultation
as well which are included in the final document.
“Differences may arise because of differing professional judgments as to the key studies, selection of
uncertainty factors or other methodological differences. Dates of assessments, and thus the body of
literature covered, may differ considerably from one organization to another.”
Since there are differences in the methodologies, how do we choose?
D. Schoen presented 4 different options for selection of the toxicity values in her .pdf document (below):
(A) Use inhalation toxicological reference values (TRVs) from one organization/program
(B) Use TRVs from several sources, using a hierarchical approach—list organizations from which to draw
values in order of preference.
(C) Compare all available values (and the underlying scientific assessments) for each chemical to
determine the value that is most appropriate.
How to determine most appropriate:
- Most recent?
- Most conservative?
- Strongest scientific rationale?
(D) Hybrid – Option A or B for most chemicals, but leave the door open to a detailed evaluation for those
chemicals for which the choice of TRV will have greatest consequences.
See the table in Inhalation TRVs for Chronic Exposure (.pdf) for advantages and disadvantages for each
of these methods.
Question: Under Option A, for any defined list of chemicals, you would only use the TRVs from a
specific program. So, this option would include old and new TRVs?
Yes, Option A would define a program and then all of the toxicity values would be derived from that
program. Depending on the program, you could have a different TRV than another program depending on
how often each program updates their TRVs.
Important to remember that we are trying to determine a starting point for the standard and it can be
updated in the future. This could determine the approach for dealing with chemicals that do not have
toxicology values today or are not being evaluated as part of this initial development process.
Kent Carlson was the second speaker and referred this file: Combination Prop 65, TAC, HAP, REL
list.xlxs. The file provided has not been approved by the U.S. Consumer Product Safety Commission; it is
a compilation of references that K. Carlson developed in 2010 for this standard.
Some of the information on the spreadsheet is out of date and needs to be updated. It starts out with
chemical and CAS number and it targets VOCs values that have been described in California 01350:
CRELs (65 chemicals) and the California Toxic Air Contaminants List. A next step is to split the list up into
carcinogenic and non-carcinogenic chemicals. Another thing to consider is whether the TRV was
developed from an inhalation or dermal exposure. The EPA HAP list and the California Toxic Air
Contaminants List are lists of designated chemicals and may not be helpful in calculating TRVs.
On the right hand side of the spreadsheet there are values from ATSDR and the EPA’s IRIS databases.
Another next step would be to add the WHO values to this spreadsheet. May want to add dates of
assessments for Prop 65 chemicals (in the listing with the chemical), ATSDR (located in the toxicological
profile report), and EPA IRIS (located in the toxicological profile report). The number of assessments and
how they were developed was mentioned and can be used to prioritize the lists. For example, Prop 65
contains over 300 chemicals and the other databases contain assessments for fewer chemicals.
Another discussion has been whether these can be separated by methodological differences. This is one
of the next steps.
On the far right, there is a household products column that lists the products that have the chemical in
question in it. This spreadsheet also contains the physical properties for each chemical, if they are
available.
Normalizing the units for Prop 65 inhalation values: If it was based on an oral reference dose, then you
have to normalize using body weight but if it was based on inhalation reference concentrations then you
have to normalize with breathing rate per day.
R. Hartsook is hesitant to use an oral value to determine an inhalation toxicity value because the group
should be considering the effect on the target organ or the portal of entry effect. There are differences
between oral and inhalation exposures in terms of kinetics, local and systemic toxicity.
There should be a focus on toxicity values derived from inhalation studies. There is an opinion that this
group should be identifying inhalation toxicity values but not developing inhalation toxicity values from
dermal or oral toxicity values. This group may need to at least identify chemicals that have high priority for
inhalation exposure that do not already have inhalation toxicity values.
There was a general discussion following the presentations about which of the four options for
development that D. Schoen presented at the beginning of this call would be a good starting point for the
development of toxicity values for this standard. A. Gebhart thinks that Option B (Use inhalation TRVs
from several sources, using a hierarchical approach) would be a good place for the group to start. The
group could pick an approach that was most applicable and then fill in with values from other
organizations and modifying them so the approach was consistent.
Need to consider whether or not we would develop an expert panel and A. Hodgson believes that this
would need some level of funding to develop modified toxicity values.
If the group decides to go with an expert panel, the process should be open and transparent and there
should be a degree of rigor.
Question: If the group chooses an agency’s methodology for non-cancer TRVs, would the same
approach be used for cancer TRVs or would the group go back and review the hierarchy again?
At this point, this group will likely recommend a methodology for non-cancer TRVs will be made to the
Joint Committee but the discussion about future development is open.
Differences in the values and the approaches between agencies are much more obvious in the cancer
assessments than non-cancer assessments. The group may agree with an agency’s non-cancer
approach but not on their approach for cancer approach. A different hierarchy/approach may be
necessary for evaluating cancer than the one used for developing non-cancer TRVs.
Pros/Cons for an Expert Panel Approach:
Cons:
 Have to have a source of funding to pay experts
 Takes away the authority of the values coming from government agencies
 Some values under strict health hazard assessment are supported by health hazard review but
are impractical to implement at the current time. Would there be a procedure for making a policy
decision beyond the scope of the findings of scientific studies? This would require another level of
expertise.
The group needs to further develop K. Carlson’s spreadsheet to include the dates of the health hazard
assessments, level of uncertainty (human studies/animal studies), etc. A subtask group may need to be
developed to review the studies to determine the level of uncertainty. The levels of uncertainty and
specific information about how the RfCs are derived are buried in the text of toxicological reports and may
take some time to find these and compile the information for each chemical.
Makes sense to start with OEHHA RELs but need to be aware of the dates of assessments from other
sources to make sure that the value takes into account the most recent, relevant toxicological studies
available.
Suggestion to determine what exists right now using databases from open, peer-reviewed processes and
divide the chemicals amongst members of the group to collect and document the following information for
each chemical: the date of the assessment, the methodology, and the uncertainty factors.
Another thing to consider is the relevant list of chemicals that the group wants to consider for emissions
from building products and furniture. This information can come from emission reports for the products,
literature, volumes of chemicals in commerce, measurements in indoor air, etc. Household products
database could be a crude place to start to shorten the list of chemicals available to a list of chemicals
commonly emitted from furniture and interior building products.
There are approximately 30 chemicals from K. Carlson’s spreadsheet that are also regulated in Germany
and France.
There was a presentation by Clif Mclellan given in June 2010 that may be relevant to this discussion and
is included in the NSF Standards Online System.