Charles Axten | PubMed Health

PubMed2004

Formaldehyde and leukemia: an improbable causal relationship.

Formaldehyde has been the subject of numerous toxicological and epidemiological investigations for almost 25 years. Though most toxicology studies have focused on the effects of the chemical on the nasal tract and respiratory system, epidemiology investigations have been more extensive evaluating the association between formaldehyde and cancers not only of the nasal cavities, nasopharynx, and lung, but also of the brain, prostate, pancreas, and hematopoietic system. Recently, three studies have been published which report on the possible association between exposure to formaldehyde and an increased incidence of leukemia, specifically myeloid leukemia. The article summarizes the results of these three studies, evaluates the evidence for causality based on recognized epidemiologic criteria, and provides an assessment that the association between formaldehyde and the increased incidence of leukemia reported in these studies is not plausible.

Carcinogens, Environmental↗

PubMed2003

Air sampling methodology for asphalt fume in asphalt production and asphalt roofing manufacturing facilities: total particulate sampler versus inhalable particulate sampler.

In 2000, the American Conference of Governmental Industrial Hygienists (ACGIH(R)) changed its 1971 threshold limit value (TLV) for 8-hour time-weighted average (TWA) exposure to asphalt from 5 mg/m(3) total particulate (generally < or =40 micrometer [microm] diameter) to 0.5 mg/m(3) inhalable particulate (< or =100 microm aerodynamic diameter) as benzene-soluble aerosol. To date, no inhalable particulate sampling method has been standardized and validated for asphalt fume. Furthermore, much of the historical data were collected using total particulate samplers, and the comparability of total versus inhalable size fractions of asphalt fume is not known. Therefore, the present study compared results from two types of asphalt fume samplers: 1) a traditional total particulate sampler with a 37-mm filter in a closed-face cassette with a 4-mm orifice (NIOSH 5042) versus (2) an inhalable particulate sampler designed by the IOM with a 15-mm orifice. A total of 75 simultaneous pairs of samples were collected, including personal and area samples from 19 roofing and asphalt production facilities operated by 7 different manufacturers. Each sample was analyzed for total mass collected and for benzene-soluble mass. Data from the two sampling methods (total versus inhalable) were comparable for asphalt fumes up to an aerosol concentration of 10 mg/m(3). However, we conclude that the traditional total particulate method is preferable, for this reason: The vast majority of asphalt fume particles are <12.5 microm in diameter. The traditional sampler is designed to collect primarily particles < or =40 microm, while the IOM sampler is optimized for collecting particles < or =100 microm. Thus, the traditional sampler is less likely than the IOM sampler to collect the larger-size fraction of airborne particles, most of which are non-asphalt dust.

Aerosols↗