Microbiological Investigations & Risk Assessment

Investigating the causal factors of microbial contamination and assessing the potential human and animal health risk is a fundamental component of accurately assessing microbial contamination events. Exponent’s practitioners are skilled in conducting microbial investigations, assessing microbial risk, and communicating sometimes sensitive findings to clients, regulators, and community stakeholders. We consult on a wide array of issues from biological fouling to mold contamination, and our team of scientists and engineers has nationally-recognized expertise in diverse fields such as chemical and mechanical engineering, clinical microbiology, ecology, environmental and industrial microbiology, epidemiology, food safety, industrial hygiene, occupational and environmental medicine, statistics, and toxicology. Several of our scientists are former employees of the USDA and FDA and are able to help clients with interaction with regulatory and public health personnel. Exponent can further assist in recall decision making and management, root cause analysis and corrective actions, and consequent litigation and insurance claims.

Microorganisms can be found in all natural environments, and have beneficial roles from degrading material to antibiotic synthesis. However, their roles can be far from beneficial when present in the wrong place or at high concentrations. Deleterious effects from microbial contamination can occur in fuel processing, storage and use; chemical, consumer products, medical devices and pharmaceuticals; food; medical devices and facilities; and built and natural environments, and the effects from contamination can vary dramatically.

Exponent practitioners work in the following industry areas frequently impacted by microbial contamination:

Biological Fouling and Biocorrosion

Biological fouling, or biofouling, can be broadly defined as damage to engineered materials and processing systems that is mediated by living organisms. Oil production and distribution systems are particularly vulnerable to biofouling; in particular, microbially-influenced corrosion (MIC) activities can lead to pipeline corrosion and associated product losses. While the fundamental mechanisms associated with MIC are the same as those associated with abiotic corrosion, understanding the ecology and activity of microorganisms in industrial systems is the key to prevention. Cooling of process waters such at industrial and utility facilities can also be impacted or have reduced efficiencies caused by biological fouling of the contact or non-contact cooling system.

Industrial and Consumer Product Contamination

Biological, chemical, and pharmaceutical contamination events are frequently associated with plant shutdowns and product recalls. Problems can result from mechanical failures, contaminated raw materials or product, materials deterioration, design defects, shipping conditions, or improper SOPs and GMPs. Plan recalls and other contamination issues can affect industries such as medical devise or various consumer products ranging from foods to pharmaceuticals to chemicals. Exponent scientists and engineers have extensive experience in contamination investigations: when needed, a multidisciplinary team can be deployed to identify the point source(s) of contamination and develop effective remedial recommendations. We work closely with client facilities engineers, QA/QC professionals, and production staff to investigate process and product contamination events. We are familiar with the relevant cGMP’s and can conduct confidential audits to ensure that client SOPs are properly developed and implemented.


No issue challenges a firm more than when a product is linked to a foodborne illness outbreak. Foodborne hazards include microbiological agents that can adulterate products and can result in harm. As scientific breakthroughs improve analytical method sensitivity and provide better traceability of products across the supply and distribution chain, growers, processors, retailers and food service operators need experts to assist in addressing allegations that products made people sick.

Exponent has been at the front-line in many microbial outbreaks assisting clients. Our consultants include former regulatory and public health officials who understand the outbreak investigation procedures used by regulatory and health departments. Members of our staff have worked with regulators at FDA and USDA, key health officials at CDC, and their state and local counterparts. We understand how to communicate issues using a science-based approach, and have the experience, skills, and staff to address these foodborne illness allegations, having worked on many of the recent high visibility microbial outbreaks.


Mold and mold spores are ubiquitous in the natural environment and are commonly found in anthropogenic environments such as buildings. The mere presence of mold and mold spores alone is not necessarily problematic; however excess moisture can lead to the amplification of fungi and molds. A broad range of health problems, including allergies, infections and toxic effects, have been described and/or alleged as being related to mold exposures. Exponent provides a team of qualified individuals that addresses the full spectrum of fungal problems in a coordinated manner.

Exponent’s industrial hygienist conduct site inspections, conduct indoor air quality assessments, oversee mold abatement and conduct verification sampling. Our staff also assess the efficacy of mold assessment and abatement work conducted by other parties and provides litigation support services, including evaluating personal injury claims due to molds found in residential or occupational settings.

Our physicians are often included in projects where personal injury from bioaerosol exposure is being alleged. Of critical importance is determination of preexisting medical conditions which helps to explain certain medical claims.

Using a multidisciplinary team approach, the genus and species of the contaminating mold or molds, the level of the mold found in product, the amount of product in distribution, the targeted consumer population and reports of alleged illness are investigated. A health hazard evaluation is performed enabling the client with Exponent to make informed recall and regulatory notification decisions.

Public Health Outbreaks

Exponent staff provides reactive assistance with public health outbreaks, and has supported public health outbreak investigations of anthrax, Coccidioides (cause of Valley Fever), Coxiella burnetii, Hanta virus, Legionella, and Noro virus amongst others. Exponent also provides pro-active public health services including corporate and government pandemic and epidemic planning and corporate risk management.

Water and Wastewater

Microbial contamination of industrial water, drinking water, recreational waters and storm water can result in significant economic, environmental and public health impacts. Land application of wastewater treatment biosolids also pose potential risks to the ecosystem from microorganisms including bacteria, enteric viruses, and other enteric parasites. Public health impacts might also include harmful algal blooms (HABs) or exceedances of fecal indicator bacteria in public recreational areas. Exponent staff has conducted numerous microbial investigations of land use applications, beaches, streams, rivers and lakes; often related to the Clean Water Act, including using microbial source tracking methodologies and microbial risk assessments.

Biological contamination of compendial water systems continues to present significant challenges to the pharmaceutical, biotechnology, and medical device industries. Bacteria, in particular, are well adapted to survival in purified water systems. Their presence leads to the contamination of process equipment, raw materials, and in some cases, product adulteration leading to recalls. Effective control of bioburden in compendial water systems requires an understanding of those factors that promote microbial growth and biofilm formation. The presence of biofilms associated with wetted surfaces gives rise to both bioburden and associated endotoxin (pyrogen) contamination. Exponent scientists and engineers have extensive experience in characterizing issues of bioburden (and other contaminants), Legionella sampling, risk assessment and development of Legionella system management plans, reviewing system designs, and developing targeted preventive and treatment strategies.

Environmental Microbiology

Microbial biodegradation of contaminants or the use of microbial bioremediation are common ecological uses of microorganisms. Such techniques have been used at CERCLA sites and at sites impacted by oil. Genetic methods help to better understand the species present and processes used in ecological settings that can be used to drive cleanup of impacted environments.