Cambridge Environmental Inc.

Cambridge, MA, United States

Cambridge Environmental Inc.

Cambridge, MA, United States
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Palma-Oliveira J.,University of Lisbon | Zemba S.G.,Cambridge Environmental Inc. | Ames M.R.,Cambridge Environmental Inc. | Green L.C.,Cambridge Environmental Inc. | Linkov I.,U.S. Army
Human and Ecological Risk Assessment | Year: 2012

Multi-pathway risk assessments (MPRAs) of contaminant emissions to the atmosphere consider both direct exposures, via ambient air, and indirect exposures, via deposition to land and water. MPRAs embody numerous interconnected models and parameters. Concatenation of many multiplicative and incompletely defined assumptions and inputs can result in risk estimates with considerable uncertainties, which are difficult to quantify and elucidate. Here, three MPRA case-studies approach uncertainties in ways that better inform context-specific judgments of risk. In the first case, default values predicted implausibly large impacts; substitution of site-specific data within conservative methods resulted in reasonable and intuitive worst-case estimates. In the second, a simpler, clearly worst-case water quality model sufficed to demonstrate acceptable risks. In the third case, exposures were intentionally and transparently overestimated. Choices made within particular MPRAs depend on availability of data as suitable replacements for default assumptions, regulatory requirements, and thoughtful consideration of the concerns of interested stakeholders. Explicit consideration of the biases inherent in each risk assessment lends greater credibility to the assessment results, and can form the bases for evidence-based decision-making. © 2012 Copyright Taylor and Francis Group, LLC.


Ames M.,Cambridge Environmental Inc. | Zemba S.,Cambridge Environmental Inc. | Green L.,Cambridge Environmental Inc. | Botelho M.J.,Secil Companhia Geral de Cal e Cimento | And 4 more authors.
Science of the Total Environment | Year: 2012

Cement kilns are known to emit polychlorinated dibenzo(p)dioxins and furans (PCDD/Fs; "dioxins"), but estimates of the amounts and patterns of these emissions vary widely. These variations may stem from a combination of factors, including the design and operating conditions of the kiln, and the fuels and raw materials fed into the kiln. The goal of this study was to examine the patterns of dioxin emissions in a large set of stack-tests at two Portland cement kilns in Portugal that use a variety of fuels. A total of 152 stack-tests provided data on PCDD/F congener concentrations during which the kilns combusted a varied mix of fuels, including petroleum coke, coal, various "special" supplemental fuels, and refinery distillation ends, which are classified as hazardous wastes. The use of coal to fuel the kilns was found to generate significantly different emission-profiles relative to the use of petroleum coke, but the addition of hazardous wastes as a supplemental fuel did not significantly alter profiles. All of the kiln emission profiles were found to differ markedly from profiles in ambient air. However, the small absolute dioxin emission rates from the kilns suggested that kiln impacts would not be detectable via ambient air monitoring, even in rural settings. © 2011 Elsevier B.V.


Zemba S.,Cambridge Environmental Inc. | Ames M.,Cambridge Environmental Inc. | Green L.,Cambridge Environmental Inc. | Botelho M.J.,Secil Companhia Geral de Cal e Cimento | And 3 more authors.
Science of the Total Environment | Year: 2011

Emissions from Portland cement manufacturing facilities may increase health risks in nearby populations and are thus subject to stringent regulations. Direct testing of pollutant concentrations in exhaust gases provides the best basis for assessing the extent of these risks. However, these tests (i) are often conducted under stressed, rather than typical, operating conditions, (ii) may be limited in number and duration, and (iii) may be influenced by specific fuel-types and attributes of individual kilns. We report here on the results of more than 150 emissions-tests conducted of two kilns at a Portland cement manufacturing plant in Portugal. The tests measured various regulated metals and polychlorinated dibenzo(p)dioxins and furans (PCDD/Fs). Stack-gas concentrations of pollutants were found to be highly variable, with standard deviations on the order of mean values. Emission rates of many pollutants were higher when coal was used as the main kiln fuel (instead of petroleum coke). Use of various supplemental fuels, however, had little effect on stack emissions, and few statistically significant differences were observed when hazardous waste was included in the fuel mix. Significant differences in emissions for some pollutants were observed between the two kilns despite their similar designs and uses of similar fuels. All measured values were found to be within applicable regulatory limits. © 2011 Elsevier B.V.


White K.L.,ImmunoToxR Inc. | Peachee V.L.,ImmunoToxR Inc. | Armstrong S.R.,Cambridge Environmental Inc. | Twerdok L.E.,Twerdok Consulting LLC | And 2 more authors.
Regulatory Toxicology and Pharmacology | Year: 2014

Female Sprague Dawley rats were exposed via inhalation to vapor condensates of either gasoline or gasoline combined with various fuel oxygenates to assess potential immunotoxicity of evaporative emissions. Test articles included vapor condensates prepared from "baseline gasoline" (BGVC), or gasoline combined with methyl tertiary butyl ether (G/MTBE), ethyl t-butyl ether (G/ETBE), t-amyl methyl ether (G/TAME), diisopropyl ether (G/DIPE), ethanol (G/EtOH), or t-butyl alcohol (G/TBA). Target concentrations were 0, 2000, 10,000 or 20,000mg/mg3 administered for 6h/day, 5days/week for 4weeks. The antibody-forming cell (AFC) response to the T-dependent antigen, sheep erythrocyte (sRBC), was used to determine the effects of the gasoline vapor condensates on the humoral components of the immune system. Exposure to BGVC, G/MTBE, G/TAME, and G/TBA did not result in significant changes in the IgM AFC response to sRBC, when evaluated as either specific activity (AFC/106 spleen cells) or as total spleen activity (AFC/spleen). Exposure to G/EtOH and G/DIPE resulted in a dose-dependent decrease in the AFC response, reaching the level of statistical significance only at the high 20,000mg/m3 level. Exposure to G/ETBE resulted in a statistically significant decrease in the AFC response at the middle (10,000mg/m3) and high (20,000mg/m3) exposure concentrations. © 2014 Elsevier Inc.


Zemba S.G.,Cambridge Environmental Inc. | Binder J.J.,Alternate Resources Inc. | Ames M.R.,Cambridge Environmental Inc. | Lester R.R.,Cambridge Environmental Inc.
18th Annual North American Waste-to-Energy Conference, NAWTEC18 | Year: 2010

Until recently, landfills and waste-to-energy (WTE) facilities were the two basic technologies available to process residual (post-recycled) municipal solid waste. These technologies have both advantages and drawbacks, and their relative merits have been debated many different ways. Risk assessments of both technologies have been used to examine their potential threats to human health and the environment, and have found both landfills and WTE facilities can be operated in an environmentally acceptable manner. Neither alternative, however, has gained general public acceptance, and planned projects are often controversial. There remains considerable skepticism, for example, that landfill liners will be effective over long periods of time, and a general uneasiness over the safety of waste combustion. The interest in emerging conversion technologies, such as gasification and anaerobic digestion, as an alternative to conventional landfills and WTE facilities is thus understandable. However, there is some concern that the environmental impacts of conversion technologies are not well understood, as no commercial facilities exist in the United States. Development of a risk assessment framework for evaluating conversion technologies will serve two purposes. First, it will ultimately facilitate objective evaluation of potential risks to health and the environment as well as comparative evaluation with respect to traditional landfill and WTE technologies. Second, it will initiate a conceptual model of environmental impacts that will be useful in identifying key emissions and data gaps. Our presentation will set forth an initial risk assessment framework, focusing on the emissions and residuals of conversion technologies, and using available data to characterize and project health risk impacts. NOMENCLATURE EC - European Commission HAP - Hazardous Air Pollutant MPRA - Multi-pathway risk assessment MSW - Municipal solid waste NAAQS - National Ambient Air Quality Standard PCDD/PCDFs - Polychlorinated dibenzo(p)dioxins and furans Syngas - Synthesis (combustible) gas WTE - Waste-to-energy. © 2010 by ASME.


Crouch E.A.C.,Cambridge Environmental Inc. | Omenn G.S.,University of Michigan
Environmental Science and Technology | Year: 2012

The current paradigm for cancer risk assessment in the United States (U.S.) typically requires selection of representative rodent bioassay dose-response data for extrapolation to a single cancer potency estimate for humans. In the absence of extensive further information, the chosen bioassay result generally is taken to be that which gives the highest extrapolated result from the "most sensitive" species or strain. The estimated human cancer potency is thus derived from an upper-bound value on animal cancer potency that is technically similar to an extreme value statistic. Thus additional information from further bioassays can only lead to equal or larger cancer potency estimates. We here calculate the size of this effect using the collected results of a large number of bioassays. Since many standards are predicated on the value of the cancer potency, this effect is undesirable in producing a strong counter-incentive to performing further bioassays. © 2012 American Chemical Society.


Zemba S.G.,Cambridge Environmental INC. | Ames M.R.,Cambridge Environmental INC. | Green L.C.,Cambridge Environmental INC.
19th Annual North American Waste-to-Energy Conference, NAWTEC19 | Year: 2011

Most ash generated by waste-to-energy (WTE) facilities in the U.S. is landfilled. Studies undertaken in the late 1980's and early 1990's indicated no significant environmental concerns associated with ash landfilling. However, in 2001, policymakers at the Massachusetts Department of Environmental Protection (MA DEP) became concerned that the "cumulative" impacts of landfills, including ash landfills, might pose a risk to human health. To address this concern, we performed an indepth assessment of impacts to air quality, and theoretical risks to health, from fugitive emissions associated with an ash landfill. Nine sources of fugitive ash emissions were modeled using methods that coupled detailed information about the site operations, ash properties, and meteorological conditions on an hour-by-hour basis. The results of these assessments, combined with ambient air data collected by others, demonstrated that the impacts from fugitive emissions of the ash were no more than negligible. Accordingly, in 2006, MA DEP revised its policy, exempting ash disposal landfills from the requirement to demonstrate no significant impact, effectively granting presumptive certainty to ash landfills that employ best management practices. Detailed analyses such as described herein, combined with robust data sets, can form the basis of more efficient regulatory policies. © 2011 by ASME.


Zemba S.G.,Cambridge Environmental Inc.
20th Annual North American Waste-to-Energy Conference, NAWTEC 2012 | Year: 2012

Odor control is a frequent issue at facilities that process municipal solid waste. Even waste-to-energy facilities, which are typically operated under "negative pressure," may be less than 100% effective at preventing the occasional release of odorous emissions. When odors travel off-property to nearby residents and businesses, the tangible exposure often elicits concerns about the specific chemicals responsible for the odor and the potential for the emissions to affect public health. However, because the gaseous compounds that may lead to objectionable off-site odors are generally different than those that might result in adverse health effects, conditions of odor and risk are not as closely linked as is sometimes assumed. While odors can be assessed through personal observations, the assessment of risk requires detailed knowledge of the composition of the emitted gases. The gas produced from the aerobic decay of municipal solid waste contains a different mix of chemicals that are not as well characterized than gas produced from the anaerobic decay of waste in a landfill (which has been analyzed by the U.S. EPA and others). Air samples were recently collected from the tipping floor of a waste-to-energy facility, analyzed for chemical composition, and evaluated for their potential to lead to off-site health risks. The composition of the gas was found to be similar to published data from other MSW handling facilities, and includes both basic hydrocarbons and some EPA-designated Hazardous Air Pollutants. Thirty-two different volatile organic compounds were detected. Ethanol was found to be the most prevalent compound, almost two orders of magnitude greater in concentration than other chemicals. Additional compounds identified in the gas samples include (in order of abundance) methyl ethyl ketone, acetone, sec-butanol, isopentane, acetaldehyde, butane, isopropyl alcohol, limonene, and 1-propanol. A case-specific atmospheric dispersion of the gases was modeled to predict off-site concentrations much smaller than levels known to cause adverse health effects. Based on odor characteristics of the gas, generically extrapolating the study to other settings suggests that short-term odorous conditions due to MSW management facilities (waste-to-energy facilities, transfer stations, etc.) do not typically correspond to significant long-term health risks. Copyright © 2012 by ASME.


PubMed | Cambridge Environmental Inc
Type: Journal Article | Journal: Environmental science & technology | Year: 2012

The current paradigm for cancer risk assessment in the United States (U.S.) typically requires selection of representative rodent bioassay dose-response data for extrapolation to a single cancer potency estimate for humans. In the absence of extensive further information, the chosen bioassay result generally is taken to be that which gives the highest extrapolated result from the most sensitive species or strain. The estimated human cancer potency is thus derived from an upper-bound value on animal cancer potency that is technically similar to an extreme value statistic. Thus additional information from further bioassays can only lead to equal or larger cancer potency estimates. We here calculate the size of this effect using the collected results of a large number of bioassays. Since many standards are predicated on the value of the cancer potency, this effect is undesirable in producing a strong counter-incentive to performing further bioassays.


PubMed | Cambridge Environmental Inc.
Type: Journal Article | Journal: The Science of the total environment | Year: 2011

Emissions from Portland cement manufacturing facilities may increase health risks in nearby populations and are thus subject to stringent regulations. Direct testing of pollutant concentrations in exhaust gases provides the best basis for assessing the extent of these risks. However, these tests (i) are often conducted under stressed, rather than typical, operating conditions, (ii) may be limited in number and duration, and (iii) may be influenced by specific fuel-types and attributes of individual kilns. We report here on the results of more than 150 emissions-tests conducted of two kilns at a Portland cement manufacturing plant in Portugal. The tests measured various regulated metals and polychlorinated dibenzo(p)dioxins and furans (PCDD/Fs). Stack-gas concentrations of pollutants were found to be highly variable, with standard deviations on the order of mean values. Emission rates of many pollutants were higher when coal was used as the main kiln fuel (instead of petroleum coke). Use of various supplemental fuels, however, had little effect on stack emissions, and few statistically significant differences were observed when hazardous waste was included in the fuel mix. Significant differences in emissions for some pollutants were observed between the two kilns despite their similar designs and uses of similar fuels. All measured values were found to be within applicable regulatory limits.

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