A comparison of the results of regulatory compliance inspections in 1999 by the states of Texas, Maine, and Washington.

Inspection outcome data provided by the state of Washington Department of Health, Division of Radiation Protection, for licensees of radioactive materials was encoded according to a system established by the Texas Department of Health, Bureau of Radiation Control. The data, representing calendar year 1999 inspection activities, were then analyzed and the results compared to previously published studies for the same year in the states of Texas and Maine. Despite significant differences in regulatory program size, age, and geographic proximity, the most frequently cited violation for radioactive materials licensees were shown to be similar for all three states. Of particular note were the violations that were identified to be consistently issued in all three states. These included physical inventories and utilization logs not performed, not available, or incomplete; leak testing not performed or not performed on schedule; inadequate or unapproved operating and safety procedures; radiation survey and disposal records not available or incomplete; detection or measurement instrument calibration not performed or records not available; and radiation surveys or sampling not performed or performed with a noncalibrated instrument. Comparisons were made in an attempt to generate a summary of the most commonly issued violations that could be generalized to users of radioactive materials across the United States. A generalized list of common violations would be an invaluable tool for radiation protection programs, serving to aid in the reduction of the overall instance of program non-compliance. Any reduction in instances of non-compliance would result in the conservation of finite public health resources that might then be directed to other pressing public health matters.

Assessment of butadiene exposure in synthetic rubber manufacturing workers in Texas using frequencies of hprt mutant lymphocytes as a biomarker.

1,3-Butadiene (BD), which is used to manufacture synthetic rubber, is a mutagen and carcinogen. Because past occupational exposures have been associated with an increased risk of leukemia, there has been a dramatic reduction in workplace exposure standards. The health benefits of these reduced levels of occupational exposure to BD will be difficult to evaluate using relatively insensitive traditional epidemiological studies; however, biomarkers can be used to determine whether there are genotoxic effects associated with recent exposures to BD. In past studies of BD-exposed workers in Southeast Texas, we observed an increase in the frequency of lymphocytes with mutations in a reporter gene, hprt. Frequencies of hprt mutant cells correlated with air levels of BD and with the concentration of a BD metabolite in urine. Average exposures to 1-3 parts per million (p.p.m.) of BD were associated with a threefold increase in hprt variant (mutant) frequencies (Vfs). We now report results from a follow-up study of workers in a synthetic rubber plant in Southeast Texas. Thirty-seven workers were evaluated on three occasions over a 2-week period for exposure to BD by the use of personal organic vapor monitors and by determining the concentration of a BD metabolite in urine. The frequency of hprt mutants was determined, by autoradiography, with lymphocyte samples collected 2 weeks after the final exposure measurement. Based on their work locations, the study participants were assigned to high-exposure (N=22) or low-exposure (N=15) groups. The BD exposure, +/-standard error, of the workers in the high-exposure group (1.65+/-0.52 p.p.m.) was significantly greater than the low-exposure group (0.07+/-0.03 p.p.m.; P<0.01). The frequency of hprt mutant lymphocytes was also significantly different in the two groups (high, 10.67+/-1.5 x 10(-6); low, 3.54+/-0.6 x 10(-6); P<0.001). The concentration of the urine metabolite was greater in the high-exposure group, but the difference was not significant. The correlation coefficient between hprt Vf and BD exposure levels was r=0.44 (CI(95), 0.11-0.69; P=0.011). This study reproduced the findings from a previous study at this plant. Although studies of butadiene-exposed workers in other countries have not detected an effect of exposure on frequencies of hprt mutant lymphocytes, we have repeatedly observed this result in our studies in Texas.

An evaluation of the effect of source and concentration on three methods for the measurement of formaldehyde in indoor air.

Three methods for measuring formaldehyde (HCHO) in indoor air were evaluated under field and laboratory conditions using different sources and concentrations of formaldehyde in air. Two impinger methods (the chromotropic acid method and modified pararosaniline method) and the Draeger short-term detector tube method (with and without activation tubes) were compared when sampling for formaldehyde from a particle board box, formalin solution, and a conventional home. Concentrations of formaldehyde ranged from 0.05-0.5 ppm in air. All samples were collected independently using personal sampling pumps and a Draeger bellows pump. The results indicate that the Draeger tube method using an activation tube gives lower results than either of the impinger methods. Without using an activation tube (concentrations greater than 0.5 ppm), the Draeger tube method was comparable to the two impinger methods. In addition, there are indications that the chromotropic acid method gives different results than the modified pararosaniline method, depending on the source of formaldehyde. The modified pararosaniline method indicated higher results than the chromotropic acid method when sampling from a particle board++ box but not from a formalin source. Overall analytical precision for each method of analysis was good.

A comparative study of respirable particulate microenvironmental concentrations and personal exposures.

Personal monitoring (PM) for respirable suspended particulate matter (RSP) of thirty subjects was performed as part of an air pollution health effects study conducted in Houston, Texas. Parallel RSP measurements were performed in the study subjects' homes and two fixed site monitoring stations. The participants' daytime activities were independently recorded by study techicians. These data were used to characterize RSP concentrations in each microenvironment visited by the participants. Four estimates of daytime exposure to RSP were calculated based on two different microenvironmental models, and home and fixed site mean daytime RSP concentrations. These estimates were compared to mean daytime personal exposure from PM. Hourly estimates of exposure were calculated from a microenvironmental model and mean hourly home RSP concentrations and compared to hourly PM data. The results of the study indicate that, as in the case of NO2, it is important to characterize indoor microenvironmental RSP concentrations according to location, sources, and concurrent activities, both qualitatively and quantitatively. Stratification of concentrations according to sources present and self-reported activity can lead to misclassification of exposures. For RSP and, probably, other pollutants with indoor sources and with short exposure integration times, adequate measures of exposure can only be obtained with very detailed and complex microenvironmental models or comprehensive personal monitoring.

A survey of typical exposures to formaldehyde in Houston area residences.

A survey of indoor air quality under warm weather conditions, in a variety of Houston area residences not selected in response to occupant complaints, revealed a distribution of indoor formaldehyde concentrations ranging from less than 0.008 ppm to 0.29 ppm, with an arithmetic mean of 0.07 ppm. Approximately 15% of the monitored residences had concentrations greater than 0.10 ppm. Formaldehyde levels were observed to depend on both age of dwelling and the structural classification of the residence. These factors are not independent and reflect the influence of more fundamental variables, such as the rate of exchange of indoor and outdoor air and the overall emission potential of indoor materials. The results of this survey suggest that considerable population exposures to excess (greater than 0.10 ppm) formaldehyde concentrations may occur in the residential environment, indicating the need for improved control strategies.

Exposure estimates for the Houston Area Asthma Study.

Procedures for determining exposure extimates for the Houston Area Asthma Study are discussed. Two residential clusters of asthmatics in the Houston area have been studied as part of an overall attempt to assess the health effects of air pollution in the Texas Gulf Coast area. Air pollutant exposure data have been produced according to a three-tier monitoring scheme, i.e. (1) continuous data from centrally-located fixed stations, (2) residential indoor/outdoor measurements, and (3) personal monitoring. This air monitoring network should yield estimates of individual exposures for use in health effect correlations.The fixed sites and mobile continuously monitor ambient levels of ozone, nitrogen oxides, sulfur dioxide, carbon monoxide, and meteorological parameters (wind speed, wind direction, temperature, dew point, solar irradiation, and precipitation). Continuous sequential integrated sampling is preformed for total suspended particulates (TSP) and, inhalable particulates (IP) (total of < 2.5µm and 2.5-15.0 µm) by dichotomous samplers for 24 hr samplers), aldehydes (bubblers), and aeroallergens (intermittent rotorod samplers). In addition to gravimetric determinations, particulate filters are routinely analyzed for sulfate, nitrate, and (every third day) trace elements. Personal monitoring includes ozone, respirable particles, nitrogen dioxide and formaldehyde. A quality assurance/control program that meets specifications established in the EPA Quality Assurance Handbook for air pollution measurement systems was implemented. Examples of results consisting of unvalidated preliminary data from the monitoring for ozone for three participants is presented and approaches to determining exposure estimates are discussed for both an integrated exposure estimate and short time period exposure estimate.

The nonuniform application of TLV's as legal workplace standards.

A survey of current Federal exposure limits for workplace air contaminants has revealed a surprising diversity of applicable TLV's. At least six different TLV lists are enforceable as legal standards by the Department of Labor. This nonuniformity is contrary to legislative intent, and is a source of administrative difficulty as well as inequity in worker protection.