Doug Trout, who is the associate director for Science in the NIOSH Division of Surveillance, Hazard Evaluations and Field Studies, said the NIOSH guidance will propose a framework for performing a needs assessment – which, Trout said, is the first step in a surveillance program. The guidance, according to Trout, also will provide recommendations for evaluating factors that are important when considering the need for, or extent of, a medical surveillance program for nanotechnology workers.
"The presence of an occupational health surveillance program – represented at the minimum level as a needs assessment – indicates that workplaces have taken appropriate steps in evaluating and preventing potential occupational exposures," Trout said last week, addressing attendees of the International Conference on Nanotechnology Occupational and Environmental Health and Safety in Cincinnati.
Trout noted that the upcoming guidance "is not a prescriptive recommendation for a specific type of surveillance program." Instead, the guidance "presents information that can be used to create appropriate occupational health surveillance to fit the needs of workers and organizations involved with nanotechnology."
According to Trout, NIOSH is recommending occupational health surveillance programs for several reasons, including the growth of nanotechnology in the workplace, the unique physical and chemical properties of nanomaterials and early evidence suggesting that "nanoparticles may have toxic effects greater than larger-size particles and at lower doses." As for the last point, Trout said that such evidence is corroborated by "air pollution epidemiology and studies of ultrafine particles."
"Although the body of evidence is not definitive, the evidence suggests that occupational exposure to nanoparticles – particularly by inhalation – may be hazardous," Trout said.
Occupational Health Surveillance 101
Trout defined occupational health surveillance "as the ongoing systematic collection, analysis and dissemination of exposure and/or health data on groups of workers for the purpose of preventing illness and injury."
"Well-designed occupational health surveillance programs," Trout explained, can:
- Help employers in the early recognition of the relationship between exposure to a hazardous substance and disease;
- Assure the safety of new substances; and
- Assess the effectiveness of existing control measures.
According to Trout, an occupational health surveillance program is comprised of hazard surveillance, medical surveillance or both.
- Hazard surveillance is "the periodic characterization of chemical or physical hazards in the workplace."
- Medical surveillance "targets actual health events or changes in biologic functions of an exposed person or persons."
Trout added that medical surveillance generally is thought of "as a tool of secondary prevention – that is, prevention designed to detect occupational health problems at an early stage." He asserted that hazard surveillance and medical surveillance "should be integrated to the greatest extent possible."
Medical screening, Trout pointed out, is a type of medical surveillance in which EHS professionals evaluate "sentinel cases of occupational illness or aggregated data from medical screening activities." Trout defined "sentinel cases" as "the detection of an individual health event that may be related to an occupational exposure and require follow-up."
"In some instances, a sentinel event will alert practitioners to elevated rates of common diseases or common symptoms that warrant follow-up investigation," Trout explained. "In other instances, a sentinel event will signal when a disease or illness is occurring in excess or in a cluster in time and space."
Needs Assessment is the First Step
In keeping with the "well-accepted" principles of occupational health surveillance programs, the upcoming NIOSH guidance will advise nanotech employers to conduct their surveillance programs "in a stepwise fashion," beginning with a needs assessment.
"The purpose of this needs assessment in an occupational setting is to determine – by performing hazard and exposure assessments – whether a health risk due to occupational exposure [to nanomaterials] exists in the workplace," Trout said. "In situations such as with nanotechnology where data are incomplete, such a risk determination may, of necessity, be qualitative."
The two main components of a needs assessment are hazard assessment and exposure assessment.
- Hazard assessment should be designed to address questions such as: What exposure agents are found in the workplace (are there single agents or multiple agents), and are their any toxicological or epidemiological data available to make an assessment of their potential toxicity or hazard? "When data are lacking for nanomaterials," Trout said, "it may be helpful to consider scientific evidence for particles with similar properties but larger size, taking into account what may be known about changes in toxicity with decreasing particle size."
- Exposure assessment, Trout explained, "involves evaluating industrial processes and characteristics of potential exposure, including relevant exposure routes, such as inhalation, ingestion, dermal or injection routes; the amount, duration and frequency of exposure; as well as whether exposure controls are in place and how protective they are."
Trout noted that the term "hazard" – in the context of the NIOSH guidance – refers to substances "with the potential to cause harm," while "risk" defines "the likelihood of harm." Trout added that risk "may be thought of as a combination of hazard and exposure."
"If the needs assessment results in a determination that a health risk is present, then medical surveillance should be further considered," Trout said.
Periodic Reassessment Will Be Necessary
Trout emphasized that because nanotechnology is a rapidly evolving field, "information may not be available to make a well-informed determination of risk."
"Given the rate at which the field of nanotechnology is changing, periodic reassessment of hazard and exposure will be a critical part of the needs assessment," Trout said. "A determination concerning residual risk at one point in time – whether positive, negative or indeterminate – should be periodically reassessed as new knowledge is gained about nanomaterials."
Just as EHS professionals will need to make periodic modifications to their surveillance programs, the upcoming NIOSH guidance – which Trout called a "living document" – will need to be updated as stakeholders learn more about nanomaterials.
"We plan for our guidance to be put on the NIOSH Nanotechnology [Web page] as a request from NIOSH to occupational safety and health practitioners, researchers, product innovators and manufacturers, employers, workers, interest groups and the general public for comment," Trout said.
This is part one in a two-part series on Trout's discussion of the upcoming NIOSH guidance for nanotechnology workplaces. Part two will detail the factors that should be considered before implementing a medical surveillance program. It also will discuss a template for a medical surveillance program that Trout said employers could implement "as a precautionary measure."