Comments received during the Health Risk Limit Rules Proposed
Amendments Comment Period and
Minnesota Department of Health response
Section I - Overview:
Minnesota Rules 1400.2310, subpart J requires that Minnesota Department of Health (MDH)
submit to the Office of Administrative Hearings “all written comments and submissions on
the proposed rule received during the comment period, requests for hearing, and withdrawals
of requests for hearing received by the agency, except those that only requested copies of
documents.” This document contains the following:
Summary of Comments Received and MDH’s Responses to Comments:
During the official 30-day comment period MDH received comments on proposed rules for
bisphenol A (BPA), triclosan, and trichloroethylene (TCE). Section II summarizes the
comments received and MDH’s responses.
MDH Response to Requests for a Public Hearing:
MDH received no requests for hearing.
All Public Correspondence Received:
After receiving rule-related comments, MDH posted the correspondence received on MDH’s
rules webpage. 1 Section III compiles all official correspondence MDH received, grouped by
chemical and those who submitted the comment.
1
http://www.health.state.mn.us/divs/eh/risk/rules/water/rules2015/comments.html
Section II - Summary of Comments Received and MDH’s Responses to Comments:
MDH received the following sets of comments in response to the proposed HRL rules
(Minnesota Rules, Chapter 4717. Parts 7860 and 7500) and the Dual Notice of Intent to
Adopt Rules that was published in the State Register on August 31, 2015. The comments are
summarized below, followed by MDH responses.
1. Bisphenol A (BPA) and comments on alternative ways to determine dose
adjustments for mouse data
Summit Toxicology and the American Chemistry Council commented that the Human Equivalent
Dose Factor (HEDF) (i.e., “Dose Adjustment Factor” or ‘DAF’) that MDH chose for the
subchronic and chronic BPA values is overly conservative and should be revised based on
information and analyses provided in the Summit Toxicology comment letter. Summit Toxicology
provided data for multiple studies that had different study designs, dose levels, and analytical
methodologies, and presented a statistical analysis of the data.
MDH had considered the available toxicokinetic data, including the mouse data, in calculating
the HRLs for BPA. The adult mouse toxicokinetic data for BPA both in the scientific literature
and provided by Summit Toxicology is conflicting. While the variety of available data might
support multiple interpretations, MDH found that the results from Summit Toxicology’s analysis
of the data were not consistent with actual test data for multiple species and dose levels. Summit
Toxicology also excluded certain data from their regression analyses in order to obtain a better
fit for the interspecies data. MDH concludes that a chemical-specific DAF based on the adult
mouse data could not be calculated with certainty. MDH’s choice of the EPA default adjustment,
chosen in accordance with EPA guidelines, is the more defensible and appropriate DAF for the
BPA values of concern to the commenters.
2. Triclosan and comments on using serum thyroxine (T4) thyroid hormone levels in
rats for risk assessment
BASF submitted a comment that the MDH use of a 20 percent reduction in T4 levels in rats as the
basis of a reference dose is inappropriate for human risk assessment and for determining the
short term triclosan HRL. BASF stated that although triclosan exposure results in a dosedependent decrease in T4 in rats, this occurs without a concomitant change in TSH or T3 levels,
and no development or reproductive toxicity has been noted in a variety of species studied.
Furthermore, humans are more resistant to changes in circulating thyroid hormones than rats,
and human volunteers exposed to 0.01 mg/kg/d triclosan for 2 weeks had no changes in thyroid
function.
Decreases in circulating levels of T4 are of concern, particularly during sensitive developmental
windows. This concern is supported by epidemiological (human) and experimental (animal)
evidence identifying hypothyroxinemia (low circulating levels of T4, whether or not TSH is
altered) as a serious risk factor for poor neurological development. Neonatal (newborn) humans
are more sensitive than adults to perturbations in circulating thyroid hormone levels, which can
lead to permanent neurological impairments. The developmental studies cited by BASF were not
specifically designed to evaluate neurobehavioral development. The lack of effects in adult
human volunteers at estimated exposures nearly seven-fold lower than the MDH short term
MDH 2015 HRL Proposed Rules
Comments and Responses
2
reference dose (less than 0.01 mg/kg-d versus 0.067 mg/kg-d) is in agreement with MDH’s
assessment. Additionally, these studies did not assess the population of primary concern (i.e.,
pregnant women, fetuses, and neonates). In the absence of sufficient data to the contrary, MDH
will consider the hypothyroxinemia (decreased T4) observed in rats relevant to humans.
Following consultation with EPA experts in thyroid endocrinology MDH used a biological
response of 20 percent based on clinical literature and knowledge regarding changes in T4 and
associated adverse outcomes.
3. Trichloroethylene (TCE) and comments on the study selected for development of
the water guidance value.
3.1 Choice of studies
The American Chemistry Council (ACC) submitted comments regarding the choice of the critical
and co-critical study for the short-term and subchronic duration HRLs for TCE. The ACC states
that because these are not US Environmental Protection Agency (EPA) guideline studies (i.e.
Guideline 870, Health Effects Guidelines, EPA) the studies have too many flaws to be used for
risk assessment. The commenter provided a detailed description of their analysis in a supplement
to the letter.
MDH does not have a requirement in their methods that the critical or co-critical studies be EPA
guideline studies. The 1998 immunotoxicity guidelines 2 cited by ACC are required for federal
programs (FIFRA 3 and TSCA 4). MDH developed reference doses using the more specific and
more recent EPA findings on TCE published in the 2011 TCE IRIS 5 document. The critical and
co-critical study were identified by EPA as key studies after a thorough review of the literature.
Additionally, MDH’s review and the peer review by EPA concluded the weight of evidence
supports the use of these studies for risk assessment.
3.2 Choice of relative source contribution
The ACC commented on the default value used for the relative source contribution (RSC). The
ACC suggested using a customized RSC that reflected current data on exposure, but did not
suggest an alternative for MDH to consider.
MDH examined the exposure data and assumptions necessary to select a default or to calculate an
alternative RSC for TCE rules. MDH found no data or rationale to support an alternative to the
default RSC for drinking water exposure to a volatile organic chemical, in which a large
inhalation exposure may come from the use of tap water for domestic activities rather than
drinking the water.
2
Health effects guideline for immunotoxicity. OPPTS 870.7800. EPA 712–C–98–351 (August 1998).
Available at http://www2.epa.gov/test-guidelines-pesticides-and-toxic-substances/series-870-health-effects-testguidelines.
3
FIFRA is the 1996 Federal Insecticide, Fungicide, and Rodenticide Act
4
TSCA is the 1976 Toxic Substances Control Act
5
TCE IRIS file http://cfpub.epa.gov/ncea/iris2/chemicalLanding.cfm?substance_nmbr=199
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Comments and Responses
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3.3 Lack of justification for developing acute and short-term rules
The ACC commented that since the ACC finds the early life studies used to develop acute and
short-term rules questionable, the ACC also finds questionable MDH’s use of intake rates for
fetal and/or infant exposure. The ACC concluded that MDH’s acute and short-term rules lack
justification.
The pairing of early life studies with early life exposures is an MDH methodology and is
therefore outside the scope of this rulemaking.
4. Request for extension of the comment period
On September 29, 2015, the American Chemistry Council (ACC) submitted an email request that,
if a hearing is not held, the MDH extend the October, 2015, comment deadline a few more days
to prepare comments on the proposed HRL for TCE.
MDH responded by email on September 30 that the rulemaking procedures described in the dual
notice would be followed.
5. Request from New Brighton to be informed of rulemaking activities
The city of New Brighton and its representatives (special environmental litigation counsel) asked
to be notified if MDH held a public hearing on the proposed rules. Counsel also asked that MDH
note that the City and legal firm are interested parties in the rule-making process.
This comment is outside of the scope of this rulemaking. MDH responded directly to New
Brighton city officials and their representatives with information that no petition for a hearing
was received and no hearing would be held.
MDH 2015 HRL Proposed Rules
Comments and Responses
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Section III. - All Public Correspondence Received:
MDH posted all comments on MDH’s rules webpage. 6 The comments and requests are
listed below.
Dr. Samantha Champ for BASF on Triclosan: Comments on Proposed Amendments to
Rules Governing Health Risk Limits for Groundwater (PDF)
Dr. Sean Hays and Dr. Torka Poet for Summit Toxicology, LLP on Bisphenol A:
Comments on Species Scaling for Human Equivalent Dose Calculations for Bisphenol A
(PDF)
Steven Hentges, Ph.D for American Chemistry Council: Bisphenol A: Comments on
"Proposed Permanent Rules Pertaining to Health Risk Limits" (PDF)
Steve Risotto for American Chemistry Council on Trichloroethylene: Proposed
Amendments to Rules Governing Health Risk Limits for Groundwater (PDF)
Steve Risotto for American Chemistry Council on Trichloroethylene: Supplement to
Comment on the Draft Toxicological Profile for Trichloroethylene (PDF)
Steve Risotto for American Chemistry Council email request for an extension of the
comment period
John Drawz on behalf of Dean Lotter, City of New Brighton, letter requesting to be
notified of a public hearing
6
http://www.health.state.mn.us/divs/eh/risk/rules/water/rules2015/comments.html
Minnesota Department of Health
Health Risk Assessment Unit
651-201-4899 or [email protected]