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Welcome to a Virtual Tour of MCEARD, the Microbiological and Chemical Exposure Assessment Research Division. Before we detail MCEARD’s capabilities and accomplishments, we’ll start with a bit of background information.
The U.S. Environmental Protection Agency must base its decisions and regulations on sound science. The generation and collection of scientific information is done, in large part, by its Office of Research and Development, commonly referred to as ORD.
The National Exposure Research Laboratory, or NERL, is one of ORD’s three national labs. NERL’s primary goal is to assess and predict human and ecosystem exposure to harmful pollutants.
Two of NERL’s remote divisions are located at the Andrew W. Breidenbach Environmental Research Center in Cincinnati, Ohio. MCEARD is one of those divisions.
Cincinnati has had a prominent role in drinking and recreational water research for quite some time. In fact, the first national drinking water standards in the US were developed at the Ohio River Sanitation Station located in Cincinnati.
Though the name and oversight of the laboratory has changed over the years, its mission remains the same: to protect public health and to provide safe drinking and surface waters.
Shortly after the EPA was formed in 1970, there was little doubt that the Agency should base its water research program in Cincinnati.
Today, the Microbiological and Chemical Exposure Assessment Research Division provides leadership in the development and use of state-of-the-science methods that determine human exposure to contaminants found in a variety of environments.
MCEARD is comprised of highly trained professionals with a broad range of expertise, including: analytical chemists, microbiologists, immunologists, molecular biologists and administrative personnel.
MCEARD researchers share their expertise in exposure studies with scientists throughout ORD and other U.S. EPA offices.
The Division also has an extensive record of partnering with other governmental organizations, academia, and the private sector, as well.
MCEARD’s research program focuses on 5 areas:
1. Drinking Water,
2. Recreational Water Quality,
3. The study of Mold as it relates to indoor air quality,
4. Dietary Exposure, especially for children, and
5. Homeland Security.
Vast improvements in drinking water quality can be attributed to many of the findings and methods pioneered by MCEARD scientists like Drs. Jack Creed, Shay Fout, Eric Villegas, Jody Shoemaker, Jerry Stelma, and many others.
MCEARD has played a prominent role in Arsenic research, generating important data to better understand and control the exposure pathways of arsenic. One team of MCEARD scientists recently developed a preservation technique to support the implementation of the Arsenic Rule by thousands of drinking water utilities.
Another team developed an improved method for detecting Disinfection By-Products (or DBPs) to enhance compliance with their regulation.
MCEARD concentrates on regulated microbial contaminants such as Cryptosporidium and other protozoan pathogens by improving detection methods, evaluating host-pathogen interactions, and developing accurate and reliable viability tests.
Our virologists are developing non-invasive methods to evaluate human exposure to viruses, assessing the effectiveness of virus detection methods in field occurrence studies, and correlating pathogen occurrence in drinking water with human exposure.
MCEARD also develops analytical methods to collect nationwide occurrence data for unregulated drinking water contaminants, focusing on common contaminants and other emerging contaminants of concern, as well.
MCEARD's chemical methods will be used nationwide to collect occurrence data for over 40 different contaminants. Using these methods, hundreds of thousands of measurements will be made at more than 4700 drinking water utilities throughout the United States.
MCEARD's chemical methods have also been adopted for other uses. For instance, our method for detecting nitrosamine has been adopted by the State of California for all of its water monitoring programs. Some of our chemists are in the process of completing methods for detecting organotins and perflurinated alkyl compounds.
With regard to unregulated microbial contaminants, MCEARD microbiologists are developing and improving methods to collect nationwide occurrence data for pathogens in drinking water.
MCEARD is currently evaluating the feasibility of using virulence factor activity relationships to assess the pathogenicity of waterborne microorganisms.
We are also using proteomics to study molecular properties that may be used to speciate microorganisms or identify virulence characteristics.
MCEARD also focuses a part of its research program on developing assays to determine if humans have been exposed to specific microorganisms.
For instance, we are evaluating the performance of a MCEARD-developed exposure biomarker that would potentially enable public health officials to identify exactly what pathogen caused a particular individual to become ill, as well as the source and time of that exposure.
MCEARD also conducts research to better understand the relationship between contaminated recreational water and gastrointestinal illness.
Leading studies to determine the relationship between recreational water quality and public health, MCEARD has developed monitoring protocols that give beachgoers more reliable information about the recreational water spots they visit.
One of our teams has developed a new 2-hour quantitative PCR method that enables beach managers to evaluate recreational water quality much more effectively, a development that is likely to reduce the incidence of swimmer illness.
MCEARD has also been working to develop improved indicators of water quality, focusing on chemical contaminants commonly found in household wastes, such as pharmaceuticals, surfactants and fecal sterols.
The following clip shows the classical and innovative approaches that MCEARD takes toward developing and testing microbiological methods for evaluating recreational water quality.
Many of the current Standard Methods for bacterial detection in recreational water involve membrane filtration. Here, a water sample is collected and filtered through a membrane.
Membranes are then placed on various growth media, depending on the target bacterium. They are then incubated anywhere from 24 hours to 8 weeks to determine if the target organism was present in a particular water sample.
Methods based on real-time polymerase chain reactions, commonly referred to as real-time PCR, are currently being developed to identify target organisms in water based on their DNA. Results can be obtained in a few hours versus the days, or even weeks, required by membrane filtration techniques.
Dietary Exposure Research
MCEARD's Dietary Exposure Research Program has been designed to reduce uncertainty in dietary exposure measurements.
We develop analytical methods for measuring contaminants, such as pesticides, in foods with minimum detection limits at levels comparable to those established in other media.
MCEARD also develops measurement protocols to collect information needed to accurately determine total dietary intake of contaminants, especially by children.
The focus of MCEARD's in-house dietary exposure research program is to determine the transfer efficiency of food items that contact contaminated household surfaces, such as wood, carpet, or in this case, tile. This type of research is necessary to determine the potential excess dietary exposures of children to pesticides, i.e., over and above that inherent in foods. Children often sit on the floor to eat, or will eat food items dropped onto the floor, which opens up possibilities for contamination during consumption. For these tests, a pesticide is sprayed onto the surface and allowed to dry. The food item, in this example bologna, is placed on the surface. After a set period of time, the food is removed and ground with an extraction aid. The mixture is loaded into a stainless steel cell for accelerated solvent extraction. Once the pesticides are extracted from the food mixture, the samples are analyzed using gas chromatography mass spectrometry.
MCEARD also supports EPA's Asthma Research Strategy. Dr. Steve Vesper has developed a molecular based method to quantify risks associated with exposure to molds. He is also in the process of establishing a relative moldiness index to evaluate the role of mold in the development and/or exacerbation of asthma in children. Among his numerous accomplishments Dr. Vesper helped to demonstrate that removing certain molds from the homes of asthmatics has led to as much as a 10-fold reduction in the need for medical interventions like emergency room visits.
MCEARD also conducts homeland security research to help the EPA fulfill its responsibility to assess the contamination of sites subjected to a chemical or biological attack, and also to monitor the decontamination of such sites.
MCEARD chemists are supporting homeland security research by developing an analytical method for determination of nerve agent degradation products, in water and soil matrices by liquid chromatography tandem mass spectrometry.
MCEARD microbiologists are developing and validating rapid quantitative methods to identify select microbiological agents in environmental matrices with such technologies as quantitative PCR.
Whether determining the levels of various environmental contaminants, measuring human risk factors associated with inhalation, ingestion, and dermal pathways, or studying human populations to ascertain the most likely sources and strengths of harmful exposures, the Microbiological and Chemical Exposure Assessment Research Division will continue to provide the premier scientific methods and information that protect people from chemical and microbial hazards.