Biomedical subjects

D E Clapp

Publications and source records attributed to D E Clapp.

5 recordsLinked to original sources

PubMed1991

Quantitative determination of trucking industry workers' exposures to diesel exhaust particles.

As part of a case-control mortality study of trucking industry workers, exposures to diesel aerosol were measured among the four major presumably exposed job groups (road drivers, local drivers, dock workers, and mechanics) in the industry. Eight industrial hygiene surveys were conducted during both warm and cold weather at eight U.S. terminals and truck repair shops. A single-stage personal impactor was used to sample submicrometer-sized diesel particles on quartz fiber filters. Laboratory and field studies demonstrated that the elemental carbon content of the particles is a useful and practical marker of exposure to vehicular diesel exhaust. A thermal-optical analysis technique was used to determine the concentration of elemental carbon in the filter samples. Overall geometric mean exposures to submicrometer-sized elemental carbon ranged from 3.8 micrograms/m3 in road (long distance) drivers (N = 72) to 13.8 micrograms/m3 in dock workers (N = 75). Geometric mean background area concentrations, measured in the same cities where workers were sampled, were 2.5 micrograms/m3 on major highways (N = 21) and 1.1 micrograms/m3 in residential areas (N = 23). A factorial analysis of variance indicated that exposures in two job groups, dock workers (particularly those exposed primarily via diesel forklift trucks, introduced relatively recently) and mechanics (working in poorly ventilated shops during cold weather), were significantly higher than background concentrations and were significantly higher than the exposures in the local and road drivers. The exposures of the truck drivers could not be distinguished from background highway concentrations but were significantly higher than background concentrations in residential areas.

Air Pollutants, Occupational↗

PubMed1989

Outbreaks of diarrhoeal illness on passenger cruise ships, 1975-85.

We reviewed data from the Vessel Sanitation Program (VSP), established by the US Public Health Service in 1975, to describe the epidemiology of shipboard diarrhoeal outbreaks, determine the risk of outbreak-related illness among cruise ship passengers, and evaluate changes in rates and patterns of shipboard diarrhoeal illness since the VSP was implemented. When the programme began, none of the cruise ships passed periodic VSP sanitation inspections; since 1978, more than 50% of ships have met the standard each year. On cruises lasting 3-15 days and having at least 100 passengers, diarrhoeal disease outbreaks investigated by the Centers for Disease Control decreased from 8.1 to 3.0 per 10 million passenger days between 1975-79 and 1980-85. The proportion of outbreaks due to bacterial pathogens (36%) did not change. Seafood cocktail was implicated in 8 of 13 documented food-borne outbreaks. The risk of diarrhoeal disease outbreaks on cruise ships appears to have decreased since implementation of the VSP but has not been eliminated.

Diarrhea↗

PubMed1989

Semen quality in workers exposed to 2-ethoxyethanol.

To evaluate whether long term exposure to 2-ethoxyethanol (2EE) may affect semen quality, a cross sectional study was conducted among men exposed to 2EE used as a binder slurry in a metal castings process. Full shift breathing zone exposures to 2EE ranged from non-detectable to 24 ppm (geometric mean 6.6 ppm). Because of the potential for substantial absorption of 2EE through skin exposure, urine measurements of the metabolite of 2EE, 2-ethoxyacetic acid (2EAA) were conducted, showing levels of 2EAA ranging from non-detectable to 163 mg 2EAA/g creatinine. Only 37 exposed men (50% participation) and 39 non-exposed comparison (26% participation) from elsewhere in the plant provided a sperm sample. A questionnaire to determine personal habits, and medical and work histories, and a physical examination of the urogenital tract were also administered. The average sperm count per ejaculate among the workers exposed to 2EE was significantly lower than that of the unexposed group (113 v 154 million sperm per ejaculate respectively; p = 0.05) after consideration of abstinence, sample age, subjects' age, tobacco, alcohol and caffeine use, urogenital disorders, fever, and other illnesses. The mean sperm concentrations of the exposed and unexposed groups did not significantly differ from each other (44 and 53 million/ml respectively). No effect of exposure to 2EE on semen volume, sperm viability, motility, velocity, and normal morphology or testicular volume was detected, although some differences in the proportion of abnormal sperm shapes were observed. These data suggest that there may be an effect of 2EE on sperm count among these workers, although the possibility that other factors may be affecting the semen quality in both exposed and unexposed men in this population or that the results reflect bias introduced by the low participation rates cannot be excluded.

Acetates↗

PubMed1987

Semen quality in papaya workers with long term exposure to ethylene dibromide.

To examine whether long term occupational exposure to ethylene dibromide (EDB) affects semen quality a cross sectional study of semen quality was conducted among 46 men employed in the papaya fumigation industry in Hawaii, with an average duration of exposure of five years and a geometric mean breathing zone exposure to airborne EDB of 88 ppb (eight hour time weighted average) and peak exposures of up to 262 ppb. The comparison group consisted of 43 unexposed men from a nearby sugar refinery. Statistically significant decreases in sperm count per ejaculate, the percentage of viable and motile sperm, and increases in the proportion of sperm with specific morphological abnormalities (tapered heads, absent heads, and abnormal tails) were observed among exposed men by comparison with controls after consideration of smoking, caffeine and alcohol consumption, subject's age, abstinence, history of urogenital disorders, and other potentially confounding variables. No effect of exposure to EDB on sperm velocity, the overall proportion of sperm with normal morphology, or YFF bodies was observed. These data strongly suggest that EDB may increase the risk of reproductive impairment in workers at exposure levels near the National Institute for Occupational Safety and Health recommended limit of 45 ppb (as an eight hour time weighted average) and far below the current standard of the Occupational Safety and Health Administration of 20 ppm.

Adult↗

PubMed1984

Measuring exposures to glycol ethers.

In 1981, NIOSH began investigating the potential reproductive health effects resulting from exposures to a class of organic solvents known generically as glycol ethers (GE). This research was begun as a result of the NIOSH criteria document development program which revealed little data available on the health effects of glycol ether exposure. Toxicologic research was begun by NIOSH and other researchers which suggested substantial reproductive effects in animals. These animal data motivated a study of human exposures in the occupational setting. In 1981 and 1982 NIOSH conducted several walk-through surveys which included preliminary measurements of exposures in a variety of industries including painting trades, coal mining, production blending and distribution facilities, aircraft fueling, and communications equipment repair facilities. The human exposure data from these surveys is summarized in this paper with most results well below 1 parts per million (ppm) and only a few values approaching 10 ppm. Blood samples were collected at one site resulting in GE concentrations below the limit of detection. Exposures to airborne glycol ethers, in the industries investigated during the collection of this data, revealed several problems in reliably sampling GE at low concentrations. It became apparent, from the data and observations of work practices, that air monitoring alone provided an inadequate index of GE exposure. Further field studies of exposure to GE are anticipated, pending location of additional groups of exposed workers and development of more reliable methods for characterizing exposure, especially biological monitoring.

Air Pollutants, Occupational↗