Howard J. Cohen

Comparison of NIOSH 5040 Method versus Aethalometer™ to Monitor Diesel Particulate in School Buses and at Work Sites

This study, undertaken initially to understand apparent differences between two recent reports of diesel particulate matter (DPM) inside school buses, involved side-by-side comparisons of two different methods for measuring ambient and occupational exposures to DPM. The NIOSH 5040 method yields time-weighted-average measurements of elemental carbon (EC) and organic carbon (OC), whereas the Aethalometer yields near-real time measures of carbonaceous particles (black carbon or BC) by optical absorption. The two methods were compared on three school buses and in three different work sites. Three side-by-side sampling configurations were used (open-faced filter with and without two different cyclones) in triplicate along with two or three Aethalometers. BC readings were correlated with results from open-faced cassettes, but there were statistically significant differences between the results of side-by-side Aethalometers. In addition, Aethalometer airflow rates were inaccurate, the instruments were sensitive to vibration, optical calibration could not be performed, and historically derived conversion factors to relate EC and BC were not appropriate. The Aethalometer could prove useful for monitoring of industrial work sites, but only after a method for external calibration and improvements in pump design and vibration isolation are developed.

Metalworking Fluid Mist Occupational Exposure Limits: A Discussion of Alternative Methods

NIOSH published a recommended exposure limit (REL) for metalworking fluids (MWF) in 1998 that was designed to prevent respiratory disorders associated with these industrial lubricants. The REL of 0.4 mg/m3 (as a time-weighted average for up to 10 hours) was for the fraction of aerosol corresponding to deposition in the thoracic region of the lungs. This nonregulatory occupational exposure limit (OEL) corresponded to approximately 0.5 mg/m3 for total particulate mass. Although this REL was designed to prevent respiratory disorders from MWF exposures, NIOSH acknowledged that exposures below the REL may still result in occupational asthma and hypersensitivity pneumonitis—two of the most significant respiratory illnesses associated with MWF. In the 8 years since the publication of the NIOSH MWF REL, neither the Occupational Safety and Health Administration (OSHA) nor the American Conference of Governmental Industrial Hygienists (ACGIH®) has recommended an exposure limit for water-soluble MWF specifically, other than their previous exposure limits for mineral oil. An informal effort to benchmark companies involved in the manufacture of automobiles and automotive parts in North America indicated that most companies are using the NIOSH MWF REL as a guide for the purchase of new equipment. Furthermore, most companies have adopted a goal to limit exposures to below 1.0 mg/m3. We failed to find any company that has strictly enforced an OEL of 1.0 mg/m3 through the use of either administrative controls or personal protective equipment, when engineering controls failed to bring the exposures to below this limit. We also found that most companies have failed to implement specific medical surveillance programs for those employees exposed to MWF mist above 1.0 mg/m3. Organization Resources Counselors (ORC) published in 1999 (on their website) a “best practices” manual for maintaining MWF systems and reducing the likelihood of MWF-related illnesses. The emphasis of this approach was on control techniques, and there was no assignment of a specific OEL for MWF due to the wide variety of fluids that exist. The ORC did suggest that maintaining exposure levels to below 2.0 mg/m3 would assist in minimizing upper respiratory complaints associated with MWF. Although the ORC manual indicated that MWF vary in composition and no single OEL is likely to be appropriate for all such fluids, it adopted a very similar concept to control banding, placing all MWF operations into a single band using similar (if not identical) controls. OSHA, in lieu of adopting a 6B health standard for MWF, has also published a voluntary “best practices” manual on their website. Their document drew heavily from the work of ORC and also incorporated information from the 1998 NIOSH MWF criteria document. Industrial users of MWF need to have guidance, such as an OEL, to determine when either engineering, administrative controls, or personal protective equipment must be implemented to protect their employees. The purpose of this article is to explore various approaches that might be taken to result in a single or multiple limits for exposures to MWF and its components. Approaches such as control banding are discussed in terms of an alternative to the use of an OEL.

Copper Exposure and Metal Fume Fever: Lack of Evidence for a Causal Relationship

A systematic search was made of the world literature concerned with possible adverse health effects of inhalation exposure to copper fume and dust. Seven reports published over the past 88 years were identified that contain original human data and purport to document that exposure to copper dust or fume caused metal fume fever (MFF) or an MFF-like syndrome. Insufficient evidence was found to conclude that exposures to copper dust and copper fume cause MFF. Limitations included absence of exposure measurements, atypical symptoms and complaints, and lack of consistency among types of work associated with symptoms. Given the extensive use of copper in many industries and operations, it is evident that if copper-induced MFF does occur, it is a rare event.

Simulated Workplace Protection Factor Study of Powered Air-Purifying and Supplied Air Respirators

A study protocol was developed to obtain simulated workplace protection factor (SWPF) data for eleven models of powered air-purifying respirators (PAPRs) and supplied-air respirators (SAR) with hoods and helmets. Respirators were tested in a chamber that allowed the simulation of 12 exercises, including 2 exercises of interest to the pharmaceutical industry. Each respirator was tested by 12 volunteers, and a total of 144 sets of test results were obtained for each device. The testing protocol allowed SWPFs up to 250,000 to be measured (limit of quantification). Median SWPFs for all respirators, except one SAR, were at or above this reporting limit. Lower fifth percentiles were above 100,000, except for one SAR previously noted. An assigned protection factor (APF) was estimated for each respirator by dividing the lower fifth percentile by a safety factor of 25. APFs ranged from 6000-10,000 for PAPRs (including one loose-fitting PAPR) and 3400-10,000 for SARs, with one exception. This SAR had a lower fifth percentile of less than 20 and an estimated APF of 1. Results indicated that most respirators tested could provide a high degree of protection for workers, although one National Institute for Occupational Safety and Health-approved SAR provided minimal, if any, protection. Direct testing in a simulated workplace seems the only method that will assure employers of choosing an adequate SAR. This may be true for other classes of respirators. Furthermore, the historical approach of establishing APFs for classes of respirators, rather than individual models, may not provide adequate protection to the wearer. This is also a serious problem for regulatory agencies seeking to promulgate respirator standard provisions such as APFs for classes of respirators.

Lead and Methylene Chloride Exposures Among Automotive Repair Technicians

Potential exposures among repair technicians engaged in vehicle resurfacing operations prior to spray painting have not been thoroughly characterized. Environmental and personal air monitoring conducted in the State of Rhode Island have shown that automotive repair technicians may be exposed to metal particulates in sanding dust and methylene chloride vapors during vehicle paint removal operations. Hand wipe samples demonstrated that metals in sanding dust adhered to the hands of workers throughout the duration of the work day and were available for incidental ingestion from the handling of food/nonfood items and hand-to-mouth contact. A blood lead (PbB) screening effort among 21 workers at 2 facilities showed that 4 non-/less-exposed workers had mean PbB levels at the U.S. geometric mean of 2.8 μg/dL, while 2 out of 9 (22%) dedicated vehicle repair technicians had PbB levels at or above 30 μg Pb/dL whole blood—the level for potential adverse reproductive effects. Methylene chloride exposures were also found to exceed the Occupational Safety and Health Administrations (OSHA) 8-hr time-weighted average (TWA) action level and permissible exposure limit (PEL) in a limited number of samples (120 and 26 ppm, integrated work shift samples). Our findings suggest that thousands of professional technicians and vocational high school students may be at increased risk of adverse reproductive and/or other systemic effects.

Preventing the soldiers of health care from becoming victims on the pandemic battlefield: respirators or surgical masks as the armor of choice.

The respiratory protective equipment necessary to protect health care workers from the novel swine-origin influenza A (H1N1) virus is not known. The knowledge gap created by this unanswered question has caused substantial debate and controversy on a global scale, leading public health organizations to feel pressured into issuing decisive recommendations despite a lack of supportive data. Changes in clinical practice caused by public health guidance during such high-profile events can be expected to establish a new standard of care. Also possible is an unforeseen gradual transition to widespread N95 respirator use, driven by public health pressures instead of science, for all outbreaks of influenza or influenza-like illness. Therefore, public health organizations and other influential institutions should take care to avoid making changes to established practice standards, if possible, unless these changes are bolstered by sound scientific evidence. Until definitive comparative effectiveness clinical trials are conducted, the answer to this question will continue to remain elusive. In the meantime, relying on ethical principles that have been substantiated over time may help guide public health and clinical decisions.

Chemical Characterization of Sanding Dust and Methylene Chloride Usage in Automotive Refinishing: Implications for Occupational and Environmental Health

Surface preparation activities conducted during automotive refinishing present several potential human health and environmental risks. This study examines the chemical composition of vehicle sanding dust and the prevalence of methylene chloride use as a basis for evaluating potential chemical exposures in the work environment, fugitive environmental releases, and take-home toxics. This article reports on the findings of (1) a statewide technology and work practices survey of 353 licensed auto body shops and (2) laboratory analyses of sanding dust representing more than 200 vehicles, 10 commercial body filler compounds, and work shirts worn during vehicle sanding while using nonventilated equipment. Survey data revealed that the majority of shops (78%) do not use ventilated sanding equipment, that most workers (55%) take their work clothes and shoes home at the end of the workday, and that 17% of the respondents used a methylene chloride-based paint stripper as an adjunct to mechanical sanding. Laboratory results showed that Pb, As, Cr, Mn, and Ni were present in the sanding dust at every facility tested. Lead concentrations in sanding dust were found to be highest at facilities that performed complete vehicle refinishing (range 770 to 7300 ppm) and at a collision repair shop that used a high-lead content body filler compound (1800 ppm). Hexavalent chromium also was found in two vocational high school paint dust samples at concentrations of 54 and 710 ppm. When total lead and chromium concentrations reached 7300 and 2300 ppm, respectively, facility sanding dust samples failed the U.S. Environmental Protection Agencys Toxicity Characteristic Leaching Procedure for hazardous waste. Metals found in the sanding dust also were present on the work shirts of technicians-ranging from 0.06 (Cd) to 81 (Mg) microg/inch2 of cloth-who sanded on paint without ventilated equipment. Results suggest that sanding dust and methylene chloride paint strippers used in vehicle resurfacing operations pose a potential hazard to human health and the environment.

Particle Size Characterizations of Copper and Zinc Oxide Exposures of Employees Working in a Nonferrous Foundry Using Cascade Impactors

This study characterized exposures to copper and zinc oxide as respirable or nonrespirable using personal impactors and compared the results with previous findings obtained using cyclones. Twenty-five sets of air samples were taken over a 10-month period using single jet cascade impactors. Five to six stages were used to capture and classify aerosols according to their aerodynamic diameter (d(ae)). These ranged from < 0.5 microm to > 10 microm d(ae). Twenty-two air samples were taken on employees casting brass alloys, and three samples were taken in areas in the vicinity where employees routinely worked. Twenty-one air samples were taken during the casting of a single brass alloy (containing 70% copper and 30% zinc), and the remaining samples were obtained from employees casting two different brass alloys: a nearly pure copper alloy and a nickel-copper alloy. The results indicated that 55-96% (by mass) of all copper aerosols collected had a d(ae) > or = 10 microm. More than 85% (by mass) of all copper exposures were estimated as nonrespirable using the current ACGIH-CEN-ISO definition. Zinc oxide aerosols were collected at all stages of the impactors, with significant amounts found to have a d(ae) > or = 10 microm. More than 60% (by mass) of all zinc oxide exposures were estimated to be nonrespirable. A comparison of data collected using impactors and cyclones demonstrated that cyclones could be used to differentiate larger aerosol particles from fumes, rather than requiring the use of impactors. It is recommended that appropriate particle size selective sampling methods be used to classify exposures of metals to dusts and fumes.

Sources of interference in field studies of diesel exhaust emissions

This article describes interferences encountered in a variety of occupational settings during industrial hygiene surveys of diesel particulate material (DPM) using the NIOSH 5040 Method. The method yields time-weighted-average measurements of elemental carbon (EC), organic carbon (OC), and total carbon (TC = EC + OC). NIOSH recommends EC as proxy for DPM, but other agencies (e.g., MSHA) regulate exposure as TC. Surveys were conducted in an engine factory and a wood treatment plant where diesel equipment was used, and in a foundry where its use was being considered. Full shift samples were collected using open-faced cassettes and cyclones fitted with 37-mm quartz fiber filters analyzed by the NIOSH 5040 Method. Non-DPM-related interferences were noted for both the OC and EC. In the engine factory and wood treatment facility, OC measurements were very high (range of 10.0-1600 microg/m(3)), while EC levels were mostly below the LOD. These findings almost certainly reflect interferences by cutting oil mists and airborne creosote respectively. In the foundry, EC levels were high and comprised mainly of larger (>4 microm) particles (open face samples: arithmetic mean = 136 microg/m(3), geometric mean = 74.0 microg/m(3); cyclone samples: arithmetic mean = 30.2 microg/m(3), geometric mean = 14.7 microg/m(3)). These findings suggest that OC interferences should be suspected if the EC:TC ratio is <0.35 and, if DPM surveys are performed with open-faced samplers, at least a small number of size-selective samplers should be employed to assure that results do not reflect EC interference by larger (i.e., >1-4 microm) particles. They also support the ACGIH decision to modify its proposed DPM TLV to specifically consider elemental carbon, rather than total carbon.

2007 Donald E. Cummings Memorial Award Lecture. The industrial hygiene profession: current and future issues.

My sincere thanks to the AIHA awards committee for selecting me as the recipient of the 2007 Donald E. Cummings award. Donald Eddy Cummings was one of AIHA’s founding members and served as its third president. He studied at West Point and received a BS degree in chemical engineering from the Massachusetts Institute of Technology. Donald Cummings began his research in 1928 at the famous Saranac Laboratory in New York studying tuberculosis. He left the Saranac lab and began developing dust control methods for the mining industry. In 1938, he began teaching industrial hygiene at the University of Colorado Medical School. Donald Cummings died in a plane crash in 1942 on his way to examine manganese exposures in a Nevada mine. AIHA established this award in 1944 in his memory. Many of the early recipients were the founders of occupational medicine, toxicology, and industrial hygiene and included: Alice Hamilton, Phil Drinker, Ted Hatch, Warren Cook, Henry Smyth, and William Yant. My selection as this year’s recipient is due in a large part to the efforts of mentors, friends, and colleagues who provided wonderful guidance and opportunities for me. It is not possible to thank each of these persons, but I would like to acknowledge that three of my former professors have received this award, including Dhorman Byers, Ralph Smith, and the 2006 award winner, Steve Levine. I would also like to acknowledge the three individuals who have most influenced my life as an industrial hygienist and as a person. The first is my mother, Florence. She was the most remarkable human being that I have had the opportunity to know, and her values and work directly impacted my decision to become an industrial hygienist. My mom was born in 1925 into a poor immigrant, Jewish family living in Somerville, Massachusetts. She graduated Somerville High School with high honors and won a scholarship to one of the state universities. However, her parents told her that they needed her income and could not afford to let her leave home for college. She worked at a local department store until she married at the age of 24. I was born a year later and shortly after my birth she developed a severe case of ulcerative colitis, which was diagnosed many years later as Crohn’s disease. She was among the earliest patients to receive ostomy surgery. She was sufficiently ill that the first year of my life was spent living with her best friend and husband. Despite the advice of her doctors, she gave birth to my brother 5 years later. My mom went on to spend the rest of her life caring for individuals having had ostomy surgery. She was a founding member of the Boston Ostomy Association (the second oldest ostomy group in the nation). She spent the early years of my life visiting women in hospitals who were depressed and sometimes suicidal after having ostomy surgery. She would often bring my brother and me with her to show young women that there was still a fulfilling life possible for them. The rest of her life she would provide a leadership role for ostomy groups both in the United States and throughout the world. She raised funds for the creation of the Ostomy Association of India and for the first nurse to come to the United States to learn how to care for ostomy patients. This nurse lived in our home while she studied in Boston area hospitals. My mom also founded an ostomy group for gay and lesbian members. She spent years raising funds for ostomy supplies for developing nations and was a director of Friends of Ostomy Worldwide when she died. Living with my mom taught me compassion, a desire to help others with my career, and never to feel sorry for whatever small obstacles came my way. My great uncle, Dr. William Stone, came to the United States at the age of seven with his older brother (my grandfather). While his older brother worked, Bill went to school and obtained a college degree in education. He went to Europe and fought in the trenches during World War I, came back home, married, and started a family. He applied to and was accepted at Columbia University for a doctorate in anatomy and