|
|
Description
Risk assessment is the quantitative or qualitative evaluation of the
potential for physical harm to result from a release of chemicals or
pathogens. Risk assessment considers information describing an actual
or potential release of chemicals or pathogens, the opportunity for
human contact with the chemicals or pathogens, the potential level of
exposure, the health effects of these agents, and the expected degree
of harm. Risk assessments can be performed for hazardous waste sites,
exposure to chemicals in the workplace or in consumer products, for
waste incinerators, and many other situations. Many federal and state
regulatory programs use or require risk assessments.
Cambridge Environmental specializes in quantitative assessment of
risks to health and the environment posed by chemical, physical, and
microbiological agents. We apply regulatory risk assessment
techniques, but also implement more rigorous methods when the
regulatory approaches are inappropriate or inadequate. We construct
models based on first principles of science and engineering, support
them by experimental data, and address uncertainties. Our assessments
are guided by local concerns, guidelines, policies, and precedents.
Risk assessment confronts uncertainties at every step. When needed, we
use probabilistic methods such as Monte Carlo simulations to quantify
these uncertainties and to characterize risk more completely. Members
of our staff are nationally recognized experts in the areas of
uncertainty and probabilistic analyses of environmental and health
risks.
We conduct multi-pathway human health risk assessments for new
facilities (e.g., electric power plants, incinerators, manufacturing
plants), existing facilities (e.g., power plants, refineries,
waste-treatment plants), and the sites of retired facilities (e.g.,
smelters, manufactured gas plants, landfills/waste disposal sites).
Substances that have been the foci of these assessments include
arsenic, lead, mercury, vanadium, chlorinated alkenes, dioxins/furans,
PCBs, pesticides, and radioisotopes. In every case, our risk
assessments are site-specific and take into account the latest
scientific and regulatory developments for the chemicals of concern.
Some of our projects have focused on ecological issues as well as on
impacts to human health. Careful assessments of effects on community
structure and ecosystem dynamics require efficient and sophisticated
tools. Among the tools employed, we have found that use of
RISK-ON-SITE — software developed by Cambridge Environmental — can
provide valuable information on environmental and ecological impacts.
For example, RISK-ON-SITE allows the overlay of habitat areas on a map
of chemical concentrations on a site; thus we may estimate contaminant
concentrations that are specific to individual habitats. This approach
is superior to the use of simple site-wide averages or hot spot
estimates.
Sample Projects
- In one recent project, we addressed health risk
concerns for the City of Akron, Ohio. The local press had printed
articles describing emissions from the city's municipal solid
waste-to-energy facility as a "toxic witches' brew."
Cambridge Environmental was called upon to assess immediate and
long-term risks to health. We held a series of meetings with the
Mayor's office, the press, and other concerned citizens; gathered
relevant data on the facility and its environs; and developed a
protocol for an holistic but efficient quantitative assessment. We
presented and negotiated this protocol with the Ohio EPA and the
Akron City Department of Health. The results of our analyses
demonstrated that risks to health of residents most affected by
stack emissions were negligible. We delivered a fully documented
report to the Ohio EPA; the report was peer-reviewed and approved.
Cambridge Environmental conveyed the results in a series of meetings
and press conferences. Dissent was defused, and our client - the
city - received high praise from the media and regulatory agencies
for its expeditious and prudent handling of the matter.
- The Massachusetts Environmental Protection Act, and
subsequently the Massachusetts Contingency Plan, required a risk
assessment for this 90-acre site in Beverly, MA. Since 1902, the
site contained the plant of the United Shoe Machinery Corp.
Activities at the site were principally related to metal-working,
together with support and utility services, including a coal-fired
power plant that was subsequently changed to oil firing. Throughout
the site's long history, various spills of oils, metals, coal ash,
and other potentially hazardous materials occurred at well-defined
locations, in addition to the random contamination that is likely to
occur on any industrial facility. The risk assessment was required
in order to evaluate whether clean-up was required, and if so to
what extent, if the site were to be developed for various different
uses in different areas.
A thorough investigation of the site resulted in 454 samples, each
analyzed for 60 chemical or physical parameters. Since different
areas of the site might be used for different purposes, a risk
assessment method that could distinguish between different areas of
the site, including indoor and outdoor areas, was required. A
comprehensive methodology, based on the use of Voronoi diagrams, was
developed and implemented as a mathematical and graphical computer
program. Each measurement was extrapolated to adjacent parts of the
site, so that every point on the site was assumed to be contaminated
at the level found in the nearest measurement point. This was done
independently for all contaminants at the site. Each area was then
treated as a source for each contaminant, and time-dependent source
models were developed for emissions and air dispersion from that
source, taking account of all available characteristics of the
source area.
The effects of the site were evaluated at a grid of 544 receptor
points spread over the site, in order to distinguish the spatial
variation across the site. The exposures from each source and each
contaminant were summed at each receptor point, and the potential
effect of such exposures evaluated by comparison with standards or
guidelines either obtained directly from regulatory bodies or
developed specifically for the purpose from the literature. A
slightly simplified version of the complete procedure was then
applied iteratively to estimate required clean-up levels, by
evaluating at each iteration the worst-case contributing chemical
and reducing the value of the clean-up level until every receptor
point met an overall risk standard.
- Reports of PCB contamination of domestic water
wells after failure of their submersible pumps led to a concern with
the potential health effects of leaks of a non-PCB containing
coolant oil in a similar line of domestic submersible water pumps.
This project was designed to estimate the magnitude of potential
leaks of oil from such pumps, and the magnitude of any health
effects that might result.
The magnitude of potential leaks of oil from pumps was evaluated by
examining historical information and by a technical, engineering
analysis of the pumps themselves. Leak rates in normal operation
were calculated by the application of physical principles to the
design of the seals in the pumps, coupled with bounding estimates
from the approximately known lifetime of the pumps. Leak rates in
catastrophic circumstances were estimated using bounding estimates
based on the total amount of oil present. Exposures to such leaks
were estimated by an analysis of typical domestic water use,
quantities of water consumed, and the layout of pipework in typical
domestic water systems, coupled with an examination of case reports
of catastrophic failures. In addition, various models for exposures
in showers and under other domestic circumstances were incorporated
into the comprehensive exposure estimates.
Evaluation of the potential health effects from exposure to the
lubricating oil used in the pumps required an analysis of the
literature on the health effects of mineral oils, and the variation
of those effects with type and constituents of the oils.
Quantitative comparisons with doses that might cause
non-carcinogenic effects showed that leaking oil pumps could not
cause such effects. Upper bound estimates were also computed on
carcinogenic effects by analysis of the original reports of a
skin-painting study of the oil. Lifetime risk estimates for
exposures from a leaking pump also turned out to be negligible.
Learn more
|
