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M S Crandall

Publications and source records attributed to M S Crandall.

8 recordsLinked to original sources
PubMed2005

A pilot study to investigate the effects of combined dehumidification and HEPA filtration on dew point and airborne mold spore counts in day care centers.

UNLABELLED: Meteorological factors such as relative humidity directly correlate with airborne fungal levels outdoors and indoors. While dehumidification alone is effective at reducing moisture necessary for mold growth, it is inadequate as a single intervention as it does not remove viable and non-viable fungal spores that are potentially allergenic. The purpose of this pilot study was to investigate whether dehumidification in combination with high-efficiency particulate arrestance (HEPA) filtration is effective at reducing airborne mold spore levels in day care centers. Two day care centers within a 2-mile radius of each other were selected. Day care center A was 2 years old with eight rooms while day care center B was 15 years old with six rooms. A high efficiency Santa Fe dehumidification unit equipped with a HEPA filter was installed in half the rooms (intervention) of each day care facility. Electronic HOBO data loggers continuously measured outdoor and indoor room dew point and temperature every 2 h throughout the study. Dew point and airborne fungal spore measurements from selected rooms with controlled air conditions were analyzed by comparing baseline measurements to those obtained at subsequent time periods over 1 year. Regression models accounted for correlations between measurements in the same room over time. Intervention resulted in a lowered average dew point from baseline by 8.8 degrees C compared with a decrease of 7.1 degrees C in non-intervention rooms across all time periods in both facilities (P<0.001). Fungal analyses demonstrated lower baseline (P=0.06) and follow-up means in intervention rooms (P<0.05), however the change from baseline to end of follow-up differed between intervention and non-intervention rooms in the two facilities. Log transformation was applied to approximate normality of fungal measurements. Dehumidification with HEPA filtration was effective at controlling indoor dew point in both facilities and at reducing airborne culturable fungal spore levels in one of the two facilities. These preliminary results provide a scientific rationale for using this intervention in future studies designed to investigate the impact of indoor mold exposure on health outcomes. PRACTICAL IMPLICATIONS: Poor indoor air quality is a recognized cause or contributing factor to health effects. Dampness and humidity have been linked to upper and lower respiratory symptoms in children and adults. This study indicates that reducing indoor relative humidity and airborne mold spore levels using high-efficiency dehumidification units equipped with HEPA filtration is feasible even in work facilities such as day care centers where traffic in and out of the building is difficult to regulate. Clinicians should emphasize to their patients the importance of dehumidification and HEPA filtration to improve indoor air quality in the home and workplace.

Air Pollution, Indoor↗
PubMed1990

Environmental epidemiologic investigations in the styrene-butadiene rubber production industry.

A review of the literature and an update that is in progress of a previous retrospective cohort mortality study of the styrene-1,3-butadiene industry are discussed. The follow-up has now been extended from April 1, 1976, through December 31, 1981, for plant B and December 31, 1982, for plant A. The person-years at risk of death have gone from 34,187 to 43,341 in plant A and from 19,742 to 26,314 in plant B. Among the death certificates received to date, observed deaths have increased in both plants, with increases in cancers of the trachea, bronchus and lung and in lymphosarcomas, reticulosarcomas, and cancers of the overall lymphatic and hematopoietic system.

Bronchial Neoplasms↗
PubMed1985

An analysis of exposure to styrene in the reinforced plastic boat-making industry.

To evaluate patterns of occupational exposure to styrene monomer in the boat-building industry, we conducted industrial hygiene surveys in seven fiberglass-reinforced plastic boat-fabrication plants. A total of 397 personal breathing zone air samples were collected on workers in four key job categories: gel coating and hull, deck, and small-parts lamination. We found that exposure to styrene in 234 (59%) of the personal samples exceeded the NIOSH-recommended time-weighted average (TWA) standard of 50 parts per million (ppm), and 96 (24%) of these samples exceeded the OSHA eight-hour TWA permissible exposure limit of 100 ppm. From highest to lowest average exposure potential, the job categories ranked in the following order: hull lamination (range 2-183 ppm, mean 78 ppm), deck lamination (range 12-160 ppm, mean 73 ppm), gel coating (range 5-94 ppm, mean 48 ppm), and small-parts lamination (range 9-130 ppm, mean 45 ppm). The former two categories composed a higher-exposure group, and the latter two tended to form a lower-exposure group. Exposures in these jobs appear to be proportional to resin consumption. Statistical analyses indicated that the parameter that most affects exposure potential is job category. Within a job category, part size, configuration, and surface area are important determinants of exposure. The principal reason for high exposures was the absence of control technologies and, in particular, the absence of adequate ventilation.

Air Pollutants, Occupational↗
PubMed1985

Mortality patterns among styrene-exposed boatbuilders.

In order to test the hypothesis that leukemia and lymphoma may be associated with exposure to styrene, cause-of-death patterns were studied at two reinforced plastic boatbuilding facilities. There were 5,021 workers who met the criterion of having worked at the two plants between 1959 and 1978. Based on industrial hygiene surveys conducted at the two plants, 2,060 individuals were determined to have worked in departments classified as having high exposure to styrene. There were 176 deaths observed among the total cohort, in comparison to 195.3 deaths expected (standardized mortality ratio [SMR] = 90). Among the high styrene exposure group, 47 deaths were observed in comparison to 41.5 deaths expected (SMR = 113). No leukemia or lymphoma deaths were observed in either the high exposure group or the total cohort. An excess of accidental deaths among the high exposure group (18 observed vs 12.4 expected) did not appear to be due to styrene's acute central nervous system effects, since none of the individuals were employed at the facilities at the time of their death. However, the possibility of a chronic effect could not be dismissed. While leukemia and lymphoma did not appear to be related to styrene exposure, the study had little statistical power to detect excesses of these diseases, due to the short length of observation and the young age of most cohort members. It was concluded that the cohort should provide increasingly useful information on chronic styrene toxicity as the population ages and the observation period increases.

Adolescent↗
PubMed1984

Cancer mortality patterns by work category in three Texas oil refineries.

A previous proportionate mortality ratio analysis revealed elevated mortality from brain tumors, stomach cancer, leukemia, and other cancers among OCAW members employed in three Texas oil refineries. In order to evaluate these findings, complete work histories of cases and a matched set of controls who died from other causes of death were obtained from company personnel records. Work histories were summarized by classifying each job title and department entry into one of several broad work categories of refinery unit operations. A worker was considered "exposed" to a work category if he was known to have worked at least 1 day in the category 15 or more years prior to his death. Maximum likelihood estimates of the relative risk for brain tumor, stomach cancer, and leukemia were calculated by work category using a procedure for matched case-control data. No strong associations for brain tumor risk were seen with any work categories. A slight association for leukemia was seen among workers in the Treating category, which included unit operations that reduce the level of aromatic and sulfur constituents of petroleum products and combine them with additives to improve their quality. Stomach cancer risk was elevated among maintenance workers and workers exposed to lubricating oils and paraffin wax processing.

Brain Neoplasms↗
PubMed1982

Environmental epidemiologic investigation of the styrene-butadiene rubber industry. Mortality patterns with discussion of the hematopoietic and lymphatic malignancies.

A retrospective cohort mortality study and an industrial hygiene assessment were undertaken in two styrene-butadiene rubber producing facilities in eastern Texas. Occupational history records were available from 1943 at plant A and from 1950 at plant B to the study cut-off date of 31 March 1976. With a two-sided test statistic, no statistically significant excesses in total or cause-specific mortality were observed for the overall worker population of either plant. However, the plant A study group demonstrated a nonsignificant statistical excess [standardized mortality ratio (SMR) of 203] for the cause-specific category of leukemia and aleukemia. Additional analyses were performed on a subgroup consisting of all white males with at least six months of employment at plant A between the beginning of 1943 and the end of 1945, a time which coincided with process and operational changes. An SMR of 278, also not statistically significant, was demonstrated for the leukemia and aleukemia cause-specific category. Due to the relative modest study population sizes, the power of this study to detect statistically significant excesses in leukemias or other malignancies of the hematopoietic and lymphatic tissues is not very large unless one is interested in substantial excesses, such as those that would correspond to a fourfold increase in risk.

Adult↗
PubMed1981

Worker exposure to styrene monomer in the reinforced plastic boat-making industry.

The National Institute for Occupational Safety and Health (NIOSH) conducted an industrial hygiene study of workers exposed to styrene monomer in the fiberglass reinforced plastic boat industry. This industry was chosen for study because of its length of operation and the high styrene monomer exposures experienced by these workers. The objective of the study was to provide extent of exposure data for specific jobs by including plants representing a cross-section of the industry. Industrial hygiene surveys were conducted at seven plants. Overall exposure to styrene monomer ranged from 2 parts per million (ppm) to 183 ppm. Mean exposures for the four primary job categories of hull lamination, deck lamination, small parts lamination and gel coating were found to be 78 ppm, 67 ppm, 44 ppm and 48 ppm respectively.

Air Pollutants↗