Wednesday, July 6, 2011

Dangers with Nanoparticles Must Be Monitored

ACOEM Issues Guidance Document for Occupational Exposure to Nanomaterials

July 5, 2011

Little is known about the effects of nanoparticles on the human body. That, coupled with the growing research data indicating adverse health effects on animals, has prompted the American College of Occupational and Environmental Medicine to offer recommendations on exposure monitoring, controls, and medical surveillance.

Research on animals indicates nanoparticles can cause adverse pulmonary effects, including pulmonary inflammation and fibrosis, as well as cardiovascular problems. There are also studies demonstrating movement of nanoparticles from the nasal cavity to the brain via the olfactory nerve tract.

"Prevention or reduction of exposure, using the hierarchy of controls seems prudent," according to the guidance document. "Engineering controls, such as source enclosure, local exhaust ventilation and HEPA filtration should substantially reduce or completely eliminate exposures."

The organization also recommends employee training in safe work practices as well as the use of respirators certified by the National Institute for Occupational Safety and Health for workers potentially exposed to nanoparticles. "NIOSH also indicates that it is prudent to consider the use of protective clothing and gloves to minimize dermal exposure, although there are no scientific data from which to select the most effective protective equipment," the document notes.

In terms of assessing workers' exposure to nanoparticles, ACOEM says there is no clear metric yet. The document says some authors advocate a control banding, which is an instrument that uses categories or bands of health hazards which are combined with exposure potentials or exposure scenarios to determine desired levels of control.

NIOSH recommends a program of hazard surveillance that includes identifying the nature of nanoparticles used, types of exposure assessment, measures to control exposures, characterizing the potentially exposed workers by job title, tasks and area, and documenting this information including changes over time.

ACOEM endorses NIOSH's recommendation for medical surveillance of workers potentially exposed to nanoparticles. It notes that there is insufficient scientific and medical evidence to recommend specific medical screening. However, it notes that if the nanoparticles are composed of a chemical or bulk material for which medical screening recommendations exist, those screening techniques should be used for workers exposed to engineered nanoparticles.

ACOEM says it supports the proper labeling of products containing nanomaterials, as well as the use of voluntary exposure registries by companies, especially when there is an indication that controls are insufficient to prevent all exposure. The organization also says more research is needed.

"Needed information is lacking regarding the appropriate exposure metric, regarding exposure data from workplace settings, and regarding toxicity data, including dose-response information and information regarding absorption, distribution, metabolism and excretion," ACOEM says. "There is also a need for techniques and equipment to permit practical and appropriate exposure monitoring in workplaces."