The Toxicologist - Society of Toxicology

Next the approach of Health Canada to managing risk of the potent renal carcinogen
ochratoxin A (OTA) in a market-based economy will be discussed. Ochratoxin
occurs naturally in many foods, such as cereal-derived staples as well as other food
commodities such as grapes, raisins, wine and coffee. Health Canada re-evaluated
the tolerable daily intake (TDI), re-evaluated the European TDI and conducted a
probabilistic risk assessment.
1535 GENERATION OF ELECTRICAL POWER WITH
WOODY BIOMASS: A SITE-SPECIFIC TECHNICAL
EVALUATION OF EMISSIONS AND POTENTIAL
HEALTH RISKS.
C. Teaf1, 5 , T. Davis2 , J. Doolittle2 , G. Morris3 , J. Levine4 and D. Covert5 .
1Florida State University, Tallahassee, FL, 2ECT, Inc., Gainesville, FL, 3Green Power
Institute, Berkeley, CA, 4American Renewables, LLC, Boston, MA and 5Hazardous Substance & Waste Management Research, Tallahassee, FL.
The generation of electric power on a commercial scale using woody biomass is receiving
attention and achieving broader application in some areas of the US. As
with any combustion facility, technical evaluations regarding potential human
health risks or ecological impacts from a biomass-fired power plant must include an
analysis of the specific characteristics of the proposed facility, including plant size,
fuel quantities and types, boiler engineering, emissions control equipment, and applicable
state or federal regulatory limits. A detailed preconstruction emission and
risk evaluation of these and other factors was conducted concerning a woody biomass-fired
facility that was undergoing regulatory review in Northcentral Florida.
Projected emissions were modeled according to standard USEPA approaches (e.g.,
AERMOD) and impacts at all locations were shown to be well below all applicable
air quality standards and guidelines. An evaluation of potential deposition rates and
environmental impacts for specific Hazardous Air Pollutants (HAPs; e.g.,
dioxins/furans, mercury) was conducted according to USEPA protocols.
Environmental concentrations of modeled HAPs showed that potential risks at all
locations were well below acceptable limits, based upon comparisons with relevant
standards and guidelines for air, soil, water, sediments and edible fish tissue.
1536 EMERGENCY DO NOT CONSUME/DO NOT USE
PUBLIC NOTIFICATIONS FOR DIRECT DRINKING
WATER ADDITIVES.
C. J. McLellan, C. C. Willhite, V. S. Bhat and G. L. Ball. NSF International,
Ann Arbor, MI.
Regulatory authorities and water purveyors are becoming increasingly concerned
with accidental or intentional adulteration of municipal drinking water supplies. As
a consequence, there is a need for short-term (acute) acceptable oral, topical, and
ocular exposure levels to be used in emergency situations to notify the public. These
levels, designated as Specific Concentration Levels (SCLs), have been derived for a
number of direct drinking water additives using an approach analogous to the U.S
EPA Reference Dose (RfD) and Health Advisory approaches. The SCLs were used
to calculate emergency “Do Not Consume” levels based on the default 10 kg body
weight and 1 L/day water consumption of a child, which is consistent with methods
used to calculate one-day Health Advisories. As examples, a Do Not Consume
level of 600 mg/L was derived for blended phosphates based on acute diarrhea after
ingestion of a single oral dose of mono- and dibasic monophosphates. Based on
mild irritation after topical application of 0.2% sodium metaphosphate to intact
skin of sensitive volunteers, a Do Not Use limit of 8000 mg PO4 /L was assigned.
Given the eye irritation seen in rabbits after direct instillation of 0.2% sodium
metaphosphate, an acute ocular contact limit of 60 mg PO4 /L served as the overall
Do Not Use level. These Do Not Consume and ocular or skin Do Not Use concentrations
for phosphates also apply to acute exposures to zinc orthophosphate. A
Do Not Consume concentration of 7 mg/L was derived for zinc from zinc orthophosphate
based on clinical reports of gastrointestinal distress. While there were
no empirical data upon which to derive a Do Not Use advisory for ocular or skin
contact to zinc from zinc orthophosphate, potential irritation associated with the
orthophosphate moiety is considered to be the governing factor for the ocular or
topical use limits. To utilize the values derived here, the risk manager must take into
account the exposure scenario and the pH of the water as well as the public health
and safety consequences associated with a lack of water.
1537 ENDPOINT SENSITIVITY IN FISH ENDOCRINE
DISRUPTION ASSAYS: REGULATORY IMPLICATIONS.
Z. Dang. RIVM, Bilthoven, Netherlands. Sponsor: J. Bessems.
Identifying potential endocrine disrupting chemicals (EDCs) needs screening for
elucidating mode of action (MOA) evidenced by biomarker endpoints and testing
for intrinsic toxicological properties showed by apical endpoints. Risk assessment,
330 SOT 2011 ANNUAL MEETING
however, is mainly based on apical endpoints but not MOA endpoints. Fish 21-day
assay (e.g. OECD TG229) is considered as a screen. But this assay includes both
biomarker and apical endpoints. This study explores the utility of results of 21-day
fish assay for risk assessment. Endpoint sensitivity was analysised by compiling data
from 142 individual studies for 21-day fish assay, 38 studies for fish sexual development
test (FSDT) and 6 studies for fish full-life cycle test (FFLC), encompassing 62
chemicals with different MOAs. Conclusions from this analysis include: 1) vitellogenin
(VTG), fecundity and gonad histology are the most sensitive endpoints for
fathead minnow, medaka and zebrafish in 21-day fish assays; secondary sex characteristics
(SSC) is a less sensitive endpoint and is likely inadequate to detect all
known MOAs. 2) Results of biomarker endpoints like VTG and apical endpoints
like fecundity from 21-day fish assay could be equally used for risk assessment. 3)
Most of low observed effect concentrations (LOEC) were comparable for 21-day
fish assay, FSDT and FFLC, which further support that data from 21-day fish assay
can be used for risk assessement. However, significant difference in LOECs was also
noted in some chemicals, suggesting that comprehensive endpoint sensitivity analysis
is needed. This paper emphasizes that a weight of evidence approach is important
to the decision making and testing strategy of EDCs.
1538 MODELING THE IMPACT OF SHORT TERM LEAD
EXPOSURE ON BLOOD LEAD LEVELS IN YOUNG
CHILDREN.
J. Donohue 1 , W. Mendez 2 and A. Shapiro 2 . 1 Office of Water, U.S. EPA,
Washington, DC and 2 ICF International, Fairfax, VA. Sponsor: E. Doyle.
The Environmental Protection Agency (EPA) Integrated Exposure Uptake
Biokinetic (IEUBK) Model can predict the risk of elevated blood lead levels in children
exposed to environmental lead from a variety of sources. A major limitation of
the model is its inability to predict the impact of short term or episodic increases in
lead exposure on blood lead levels. The Office of Water (OW) contracted with ICF
International to determine if the IEUBK model could be adapted so that it could
predict changes in blood lead levels over timeframes consistent with a drinking
water utility’s quarterly monitoring program. ICF updated the background levels of
lead in ambient air, soils, household dust, drinking water and diet used by the
model. They devised an interface for the model that facilitated data entry and batch
operation. The model was calibrated to ensure that the background blood lead projections
(with typical drinking water exposure concentrations) were consistent with
the distributions of blood lead levels seen in the Centers for Disease Control and
Prevention’s National Health and Nutrition Examination Survey (NHANES) monitoring
program. The calibrated model has been used to estimate impacts on blood
lead distributions in children exposed to increases in lead from drinking water. The
model was found to provide consistent results for exposure averaging timeframes as
short as three months. Monitoring under the EPA Lead and Copper Rule involves
measuring lead concentrations in first-draw tap samples after the water has been
stagnant for at least six hours which does not represent average human consumption.
However, the adapted IEUBK model allows the OW to examine the incremental
impact of hypothetical increases in average daily lead exposures on blood
lead levels in young children and thereby inform projections of potential health
risks. [The views expressed in this abstract are those of the authors and do not necessarily
reflect the views or policies of the U.S. EPA.]
1539 THE COUNCIL OF CANADIAN ACADEMIES EXPERT
PANEL ON THE INTEGRATED TOXICITY TESTING OF
PESTICIDES.
M. Trainer and L. Ritter 1, 2 . 1 Council of Canadian Academies, Ottawa, ON, Canada
and 2 School of Environmental Sciences, University of Guelph, Guelph, ON, Canada.
Canada relies on well-established animal-based models and test systems to assess the
safety and efficacy of chemicals and pharmaceuticals, including pesticides.
Alternative testing strategies, including in vitro assays and “omics” technologies,
represent an exciting opportunity for the development of tests that can evaluate a
larger number of compounds, in systems that may more reliably predict potential
adverse effects in humans. This approach also has the potential to identify the cellular
mechanisms that may be the root cause of adverse effects. These new approaches
may reduce the reliance on animal-based test systems and increase the efficiency
and volume of testing, while maintaining the highest levels of scientific
rigour. New legislation in the US and Europe will significantly increase the testing
burden that cannot be met by the current toxicity testing paradigm. Integrated approaches
for toxicity assessment may represent the means by which adequate safety
testing, harmonized internationally, can address this challenge. The Pest
Management Regulatory Agency (PMRA) of Health Canada requested that the
Council of Canadian Academies convene an expert panel to evaluate the use of integrated
testing strategies (IATA) for the regulatory risk assessment of pesticides.
Pesticide formulations represent, on the one hand, one of the most data-rich chem-