Reported single car and truck accidents due specifically to driver 'fatigue' for the 4-year span of 1980-1983 were analyzed for 24-hr, 7-d and 1-yr patterns. Three types of data were examined: (1) accidents in rural Texas, (2) accidents only in San Antonio, the fourth largest city in Texas and (3) accident ratio (number of accidents per time interval divided by traffic volume for the interval) in this city. A statistically significant seasonal variation of relatively low amplitude with peaks in May and July was detected only for accidents in rural areas. High-amplitude periodicities of 7 d were evident in all the data sets, with a peak on the weekend. A very prominent 24-hr pattern was detected as well, with the acrophase determined by single cosinor around 0300. A slight secondary peak in accidents, around 1500, was evident in the data from the rural areas. This secondary peak represented a 12-hr rhythm in addition to the 24-hr. Overall, features of the temporal patterns in accidents over 24 hr and over the year in urban and rural areas differed only slightly. Accident ratios yielded results similar to accident frequencies. However, with regard to the rural data, the shape of the 24-hr temporal pattern varied with driver age; older drivers exhibited a flatter curve with a more pronounced afternoon rather than early morning (around 0300) peak.

A household health survey of residents living near two hazardous waste disposal sites in Calcasieu Parish, Louisiana was conducted in 1981-1982 as part of a comprehensive study of the effects of those sites on the environment and on the health of nearby residents. An unexposed community was included in the health survey for comparison. Due to media coverage and public concern about the sites, two potential indices of reporting bias, hypochondriasis and respondent's opinion about the environmental effects of waste sites, were included in the survey. Because air and water quality data showed little evidence that hazardous concentrations of chemicals were being released from the sites, questions were raised about the interpretation of the health survey data. The data were analyzed, therefore, for the association between symptom reports and the potential indices of reporting bias. Hypochondriasis scores were associated with symptom reports regardless of location of residence while an individual's opinion showed a different pattern by area of residence. Respondents living near one of the waste disposal sites who answered "yes" to the opinion question were 2-3 times more likely to report some types of symptoms than residents of the comparison community. In contrast, there was little difference in symptom reports between the exposed and comparison communities for those answering "no" to the opinion question. The usefulness of self-reported symptom data in studies of communities near hazardous waste disposal sites is discussed, and attention is called to the need to develop measures sensitive to reporting bias in epidemiologic studies.

Lead and cadmium concentrations were measured in eggs and tissues of downy young, prefledgling, and adult Royal and Sandwich Terns collected from Galveston Bay, Texas. These species do not differ significantly in the amount of heavy metals they accumulate; however, they differed from other species of the same trophic level from Galveston Bay in degree and pattern of temporal accumulations of these metals. Lead levels were lower in terns, but cadmium levels in adult terns were higher than those of other species. The prefledglings of other species at this trophic level have lead and cadmium concentrations which are similar to those found in adults. In contrast, the concentrations of the metals in adult terns are markedly higher than those found in prefledgling terns. This suggests that accumulation of metals continues as the birds age.

Evaluation of fibers and total particulate generated during the servicing of drum brakes on motor vehicles as well as during the resurfacing (arcing) of brake shoes was conducted. Conditions for the studies were based on review of contemporary (approximately 1950-1980) working practices in the industry. This work was conducted in two parts. Phase 1 estimated the release of asbestos fibers and total particulate during brake inspection and replacement of light-duty vehicle rear drum brakes at an auto/truck repair facility. Two distinct work practices were evaluated: One rear wheel from each vehicle was serviced using compressed air to remove dust while the second rear wheel was serviced without compressed air. Area and personal monitoring of fiber levels demonstrated counts (without compressed air) that ranged from 0.05 to 0.2 f/cc. Fiber counts when using compressed air averaged from 0.05 to 0.9 f/cc. Results from real-time aerosol monitoring indicated elevated dust levels for about 15 minutes after blow out. With shop doors open, dust levels increased to 5.0 mg/m3 at blow out and returned to 0.08 mg/m3 within two minutes. When the shop doors were closed, the dust levels reached 13.5 mg/m3 at blow out and decreased to 1.68 mg/m3 within one minute and to background within 14 minutes. The Phase 2 series evaluated the release of fibers and other particulate from are grinding. For operations conducted under conditions simulating a workplace, a mean of 0.19 f/cc +/- 0.16 was determined. Dust levels averaged 0.25 mg/m3 +/- 0.05. Brake service monitoring in these tests demonstrates that asbestos fiber concentrations, considered on a time weighted average basis, should not exceed currently acceptable workplace standards whether or not the worker uses compressed air, nor during the arc grinding process when arcing is conducted in accord with the design of the equipment.

An occupational study was conducted for a firm employing 22 pest control operators (PCOs) exposed to three organophosphorus insecticides. Measurements of 8-hour exposure levels were less than: 131.0 microgram/m3 for Vaponite; 41.0 microgram/m3 for Diazinon; and 27.6 microgram/m3 for Dursban. Twenty-four-hour urines analyzed for alkyl phosphates showed the presence of metabolites for these three pesticides. The effect of this exposure is reflected by a statistically significant inhibition of plasma acetylcholinesterase (AChE) among the PCOs as AChE values of either group. Although physical examinations detected no apparent toxic effects in the study group, biological sampling results indicated a need for personal protective equipment during the handling and application of these pesticides.