Abstracts (PDF file, 1.8MB) - Society for Risk Analysis

SRA 2013 Annual Meeting Abstracts
T1-D.1 Walderhaug, MO*; Menis, M; Anderson, SA; U.S. FDA
CBER; mark.walderhaug@fda.hhs.gov
Use of an Administrative Database to Characterize
Babesiosis Occurrence in the United States, 2006-2008
Babesiosis is a zoonotic disease caused by several species of
protozoan parasite of the genus Babesia. This illness is typically
spread to humans by tick bite. The symptoms of babesiosis
range in severity from asymptomatic to high fever with
hemolytic anemia. Symptoms are more likely to be severe for
cases where the infected person is very young, very old, or
immunocompromised. Blood units containing babesiosis that
were collected from asymptomatic blood donors represent a
threat to blood recipients, and there is no approved screening
test at present. To assess the risk of transfusion transmitted
babesiosis, we undertook an analysis to estimate the number of
potential carriers of babesiosis that could be donating.
Babesiosis became a nationally notifiable disease in 2011,
however before 2011, the illness was sporadically reported to
the CDC. We performed a nationwide study of the diagnosis of
babesiosis in the inpatient, outpatient, skilled nursing facility,
and carrier standard analytical Medicare enrollment files for
calendar years 2006 to 2008. Our findings show that estimates
of state-specific rates from our study are up to ten times higher
than nationally reported rates at the time. Babesiosis rates
were highest in the Northeastern states of the U.S. The rates of
babesiosis in males over 65 years in age were significantly
higher than rates in females which may reflect higher
exposures to ticks in Babesia-endemic areas by males partaking
in outdoor activities. Accurate estimates of the rates of
asymptomatic cases of babesiosis in blood donors is an
important factor in estimating the benefits and risks of
screening blood donors for carriers of babesiosis. The use of
these results in a general population risk assessment is limited
in that the database used provides data on the elderly but not
on the general population. Large administrative databases may
have some limitations, but they may also be useful sources of
health information for risk assessments.
T1-E.3 Wang, B*; Gray, GM; George Washington University;
bingwang23@gwu.edu
Predicting long-term Benchmark Dose from short-term
studies in National Toxicology Program toxicity tests
Animal toxicity studies play a major role in risk assessment by
providing regulators with dose-response data to estimate health
risks in humans. However, there is a push to find more
effective, efficient and less animal-intensive methods to assess
the risk and yield reliable health risk values (like the Reference
Dose (RfD)). This study compared short-term (3 months) and
long-term (2 years) toxicity data of 41 chemicals in National
Toxicology Program (NTP) to evaluate whether well-conducted
short-term studies may yield data as reliable as long-term
studies in identifying lowest doses associated with non-cancer
adverse effects. Lower confidence limits of Benchmark Doses
(BMDLs) were computed for non-neoplastic lesions, final mean
body weight and mean organ weight. Linear regression was
performed to predict long-term BMDLs and RfDs from
short-term data. Concordance of affected organs relevant to the
lowest short-term and long-term BMDLs was assessed. In
addition, similar analysis was performed by species-sex groups.
Interestingly, 34 of 41 chemicals (83%) had a less than 10-fold
difference between the BMDLs of short-term and long-term
studies. The linear regression showed statistically significant
positive association between short-term and long-term BMDLs
and RfDs. However, only nine of 41 chemicals (22%) had
matching affected organs between short-term and long-term
studies. By-group analysis showed a similar strong quantitative
but weak qualitative association between short-term and
long-term studies. The findings suggest the risk assessed in
short-term animal studies provided a reasonably quantitative
estimate of that based on long-term studies. However, the
limited concordance of adverse effects within rodent species
should be considered in interspecies extrapolation from animals
to human in risk assessment process.
P.123 Wang, Y; Georgia Institute of Technology;
yan.wang@me.gatech.edu
Nanoscale risk assessment and uncertainty quantification
in atomistic simulations
Uncertainties in atomistic simulations imply the associated
risks in simulation-based materials and drug development. Lack
of data, conflicting information, numerical and measurement
errors are the major sources of epistemic uncertainty in
simulation. In particular, the sources of model form uncertainty
for molecular dynamics (MD) include imprecise interatomic
potential functions and parameters, inaccurate boundary
conditions, cut-off distance for simplification, approximations
used for simulation acceleration, calibration bias caused by
measurement errors, and other systematic errors during
mathematical and numerical treatment. The sources for kinetic
Monte Carlo (kMC) simulation include unknown stable and
transition states, and imprecise transition rates. In this work,
we illustrate the sensitivity and effect of model form
uncertainty in MD and kMC simulations on physical and
chemical property predictions. A generalized interval
probability formalism is applied to quantify both aleatory and
epistemic uncertainties. New reliable MD and kMC simulation
mechanisms are proposed, where the robustness of simulation
predictions can be improved without the traditional
second-order Monte Carlo style sensitivity analysis. Examples
of engineering materials and biochemical processes are used to
demonstrate the new nanoscale risk assessment approach.
P.69 Wang, M*; Lambertini, E; Micallef, SA; Pradhan, AK;
University of Maryland, College Park, MD; meowang@umd.edu
Risk Assessments for Listeria monocytogenes and
Salmonella spp. in Melons
In the past decade, with the increasing public preference for
fresh produce, the risk of illnesses associated with consuming
raw and minimally processed fruits and vegetables has drawn
increased scrutiny from various stakeholders including
consumers, industry, government, and academia. Annual
consumption of non-citrus fresh fruits, including melons,
increased 45.5% from 1976 to 2009. Melons are highly popular
due to their high nutrition value and the attractive natural
flavor. However, melons are vulnerable to pathogen
contamination because they are grown on ground, minimally
processed, and eaten raw. Therefore, melons are considered as
the second highest fresh produce commodity of concern for
microbial risk. Salmonella spp. and Listeria monocytogenes,
two of the most deadly foodborne pathogens, have been
associated with melons contamination, recalls, and most
importantly two recent large-scale outbreaks in 2011 and 2012.
While government guidelines on Good Agricultural Practices
and post-harvest Best Practices have been published for
cantaloupes, no quantitative estimate of risk and mitigation
effectiveness are available for any melon variety. In support of
such quantitative risk assessment efforts, the goal of this study
was to systematically review existing data on the risk of
contamination from Salmonella spp. and Listeria
monocytogenes and their ecology in the melon production
chain. Specific objectives were to review: (i) production and
consumption of common melon varieties (cantaloupe,
honeydew, and watermelon), (ii) potential contamination
sources in the farm-to-fork supply chain, (iii) prevalence and
survival of pathogens associated with melons, and (iv) potential
intervention strategies for risk reduction in the melon industry.
This systematic review synthesizes critical information needed
for conducting farm-to-fork quantitative microbial risk
assessment (QMRA) models for L. monocytogenes and
Salmonella spp. on melons.
December 8-11, 2013 - Baltimore, MD