The association of the original OSHA chemical hazard communication standard with reductions in acute work injuries/illnesses in private industry and the industrial releases of chemical carcinogens

BACKGROUND

OSHA predicted the original chemical Hazard Communication Standard (HCS) would cumulatively reduce the lost workday acute injury/illness rate for exposure events by 20% over 20 years and reduce exposure to chemical carcinogens.

METHODS

JoinPoint trend software identified changes in the rate of change of BLS rates for days away from work for acute injuries/illnesses during 1992-2009 for manufacturing and nonmanufacturing industries for both chemical, noxious or allergenic injury exposure events and All other exposure events. The annual percent change in the rates was used to adjust observed numbers of cases to estimate their association with the standard. A case-control study of EPA's Toxic Release Inventory 1988-2009 data compared carcinogen and non-carcinogens' releases.

RESULTS

The study estimates that the HCS was associated with a reduction in the number of acute injuries/illnesses due to chemical injury exposure events over the background rate in the range 107,569-459,395 (Hudson method/modified BIC model) depending on whether the HCS is treated as a marginal or sole factor in the decrease. Carcinogen releases have declined at a substantially faster rate than control non-carcinogens.

DISCUSSION

The previous HCS standard was associated with significant reductions in chemical event acute injuries/illnesses and chemical carcinogen exposures.

The need for data harmonization--a response to Boden and Ozonoff

Boden and Ozonoff's undercount estimates in their recent Commentary rely on three assumptions for which no quantitative literature references are provided. Alternatively, we show that findings in both studies and published data indicate lower upper-bound estimates for the undercount range. Am. J. Ind. Med. 53:854-855, 2010. (c) 2010 Wiley-Liss, Inc.

The law and incomplete database information as confounders in epidemiologic research on occupational injuries and illnesses

BACKGROUND

Capture-recapture studies report undercounting of work injuries/illnesses with days away from work (DAFW) in the Bureau of Labor Statistics annual Survey of Occupational Injuries and Illnesses (BLS SOII) by 25-68% depending on the state and undercounting by various state workers' compensation (WC) systems of eligible claims by 5-35%.

METHODS

Statutory/regulatory criteria defining eligible cases are used to adjust counts in the 1998-2001 Minnesota's WC system and the BLS SOII to permit comparison and to evaluate the recent studies. Missing information in the employer database used in the capture-recapture studies is tabulated. An attempt is made to harmonize results with two additional databases counting work injuries.

RESULTS

Counts in the BLS SOII moderately undercount by 10-16% the number of WC cases. We believe that matching in capture-recapture studies is adversely affected by misperceptions regarding the application of statutory/regulatory eligibility criteria and by missing data. The result is that the reported undercounts in both the BLS SOII and several state WC databases are overstated in the capture-recapture studies. Although three of four databases can be approximately harmonized, the fourth cannot.

CONCLUSIONS

More precisely targeted information is needed before decisions regarding redesign of the BLS survey are made or before legislative or administrative changes in the WC are contemplated.

Theoretical Modeling and Optimization of the Detection Performance: a New Concept for Electrochemical Detection of Proteins in Microfluidic Channels

In this work, we present a complete theoretical analysis of a new concept of electrochemical detector for application in proteomics upon considering two band microelectrodes performing in generator-collector mode. This concept of an original electrochemical detector is aimed at the detection of proteins following their separation in microfluidic biochips. The theoretical analysis is based on the use of the time-dependent coordinate transformation which allows performing precise modeling for a wide range of the key parameters governing the electrochemical detector performance. This allows defining a precise optimization procedure for its best efficiency upon considering the qualitative and quantitative effects of each of the main operational parameters.

Methodologic issues in the use of workers' compensation databases for the study of work injuries with days away from work. I. Sensitivity of case ascertainment

BACKGROUND

Case ascertainment costs vary substantially between primary and secondary data sources. This review summarizes information on the sensitivity of state administrative databases in workers' compensation systems for the ascertainment of days-away-from-work (DAFW) work injuries for use in modeling studies.

METHODS

Review of the literature supplemented by data from governmental or organizational reports or produced for this report.

RESULTS

Employers currently appear to provide workers' compensation insurance coverage for 98.9% of wage and salary workers. Wage and salary jobs account for approximately 90% of jobs in the United States. In industries such as manufacturing, the fraction of covered jobs is probably closer to 98%. In Minnesota, the number of DAFW cases ascertained by the Bureau of Labor Statistics' annual survey of occupational injuries and illnesses is approximately 92-97% concordant with the number of wage compensation claims for injuries producing DAFW over the period 1992-2000, once adjustments are made to permit direct comparisons of the numbers. The workers' compensation databases provide information for more than 95% of the total DAFW resulting from work injuries. Covariate estimates are unaffected by this less than 5% loss because effects appear dependent on time from injury.

CONCLUSIONS

Statewide workers' compensation administrative databases can have substantial utility for epidemiologic study of work injuries with DAFW because of their size, using high sensitivity for case ascertainment as the evaluative criterion.

Claim rates of compensable back injuries by age, gender, occupation, and industry. Do they relate to return-to-work experience?

STUDY DESIGN

A retrospective cohort study of Michigan workers' compensation cases involving back injuries in 1986 and 1987 with incidence and outcome data.

OBJECTIVE

To determine claim rates by age, gender, and industry or occupation for compensable back injuries and to investigate the relation between occupation and return to work.

SUMMARY OF BACKGROUND DATA

The cohort of 24,094 Michigan workers' compensation cases from 1986 and 1987 in which claimants were compensated for back injuries was reviewed. Compensation eligibility requires more than 7 days' disability after injury.

METHODS

Claim rates for back injuries by age, gender, and industry or occupation using employment data interpolated from 1980 and 1990 Census 1% Public Use Microdata Samples. Cox proportional hazards analysis was performed for return to work in the first 8 weeks after injury, with occupation coded at the three-digit level.

RESULTS

All-age claim rates for Michigan compensable back injuries by occupation ranged between 0.03% and 1.7% annually (0.39% for all cases) and were generally higher in women in white collar occupations and in men in blue collar occupations. The claim rate peaked in men in the 25-34 year range, with the highest rates in manual labor occupations. The peak claim rates by age were less marked in women, tending to occur broadly throughout the 25-44-year range. Similar all-age values were recorded by industry. The male-to-female risk ratio over all occupations does not vary by age and is approximately 1.4:1. As the classification of occupation became more detailed, large differences in risk were documented within major occupation groups. The highest risk in this study was approximately 6% annually for 25-44 year old men in driver-sales (beverage truck drivers and delivery workers). Only 7 of 40 occupation categories showed a significant relative hazard for return to work in the first 8 weeks after injury, and these were blue collar occupations with earlier return than the reference sales category. For Michigan compensable back injuries, a rough estimate of the true annual incidence of new claims is 94% of the reported claim rate.

CONCLUSIONS

The relative risk of compensable back injury is generally higher for females in white collar occupations, higher for males in blue collar occupations and approximately equal in service occupations. Although the risk of back injury is related to occupation, the same occupational factors do not operate as a barrier to return to work.

Diagnostic and management procedures for compensable back injuries without serious associated injuries. Modeling of the 1991 injury cohort from a major Michigan compensation insurer

STUDY DESIGN

A retrospective cohort of 2425 workers with compensated back conditions was created from the 1991 compensated cohort of the largest compensation insurer in Michigan by linking computerized information on social and demographic factors, diagnostic and management procedures, and cumulative missed worktime.

OBJECTIVE

To describe medical care use from date of injury in 1991 to mid-1993 by type of back condition, to identify factors affecting this use, to determine the effect of alternative model selection strategies on identifying such factors, to investigate the timing of surgery and the use of diagnostic studies in patients with displaced or herniated discs with and without surgery, and to compare the use of medical care in the study group with that recommended by national expert panels.

SUMMARY OF BACKGROUND DATA

Despite the enormous costs involved in medical care for patients with work-related back injuries, almost no information on the use of medical care is available for compensated back injuries by diagnostic and procedure code.

METHODS

Use of medical care was grouped into 18 categories for tabulation. Factors affecting use of medical care were identified by logistic regression, supplemented by Cox analysis for time to first procedure. The Hosmer-Lemeshow chi-square statistic was compared with the Bayes Information Criterion for evaluating model fit. Overall model utility was evaluated by comparing receiver operating characteristic curves generated by the model. For patients with displaced or herniated discs, algorithms were used to identify the diagnostic procedures performed before and after the first surgery and the amount of time that passed before each procedure was performed.

RESULTS

In patients with diagnoses of disc displacement or herniation or vertebrogenic neuritis, approximately 80% underwent radiography to obtain plain views of the spine, 75% underwent diagnostic imaging, 45% underwent electrodiagnostic procedures, and 24% underwent spinal surgery (29.3% had surgical procedures among those with disc conditions). In patients with diagnoses of back sprain or other symptomatic diagnoses, the percentages for the first three procedures are approximately 70%, 12%, and 12%, respectively. Diagnostic category, age, gender, and cumulative missed worktime predicted the receipt of diagnostic and treatment procedures. Women were 30% less likely to undergo computed axial tomography or magnetic resonance imaging and 50% less likely to undergo spinal surgery. Median time to spinal surgery was twice as long in the group that underwent diagnostic imaging and electrodiagnostic testing before surgery (134.5 days). Of the 622 patients with disc displacement/herniation, 510 (approximately 80%) had initial diagnostic imaging studies, and, of the 510, 162 (approximately 30%) had surgery. Thirteen (8%) were reoperated. Of the 162 patients who had surgery, 46 (approximately 30%) had follow-up diagnostic imaging, and, of the 46, nine (approximately 20%) were reoperated. Of the 348 managed conservatively, 96 (approximately 30%) had follow-up diagnostic imaging.

CONCLUSIONS

The data suggest only modest differences in the use of medical care between this study group and noncompensated study populations from previous reports. The authors of this study estimate that 27% of diagnostic imaging studies and 43% of plain radiography of the spine could have been avoided if then available Canadian recommendations or current American, guidelines had been followed. The gender effect remains unexplained and needs to be investigated in additional studies. There was an increase of 6% in the use of surgery in compensated patients compared with the use of surgery in a recent American series involving traditional health insurance, but this may be associated with greater work disability in the compensated group. The results of the current study suggest that the use and reporting of model selection strategies and the use of receiver operati

Factors affecting first return to work following a compensable occupational back injury

Occupational back injuries produced $27 billion in direct and indirect costs in 1988. Predictors of prolonged disability have generally been identified in selected clinical populations, but there have been few population-based studies using statewide registries from workers' compensation systems. This study uses a 1986 cohort of 8,628 Michigan workers with compensable back injuries followed to March 1, 1990. Cox proportional hazards analyses with nine categorical covariates identified factors predicting missed worktime for the first disability episode following the injury. The model distinguished factors affecting the acute (< or = 8 weeks) and chronic disability periods (> 8 weeks). The first disability episode following injury contains 69.6% of the missed worktime observed through follow-up. In the acute phase, which contributes 15.2% of first episode missed worktime, gender, age, number of dependents, industry (construction), occupation, and type of accident predict continued work disability. Marital status, weekly wage compensation rate, and establishment size do not. Beyond 8 weeks, age, establishment size and, to a lesser degree, wage compensation rate predict duration of work disability. Graphs show the predicted disability course for injured workers with specific covariate patterns. Future efforts to reduce missed worktime may require modifications in current clinical practice by patient age group and the development of new strategies to encourage small and medium-size employers to find ways to return their injured employees to work sooner. Recent federal statutes covering disabled workers will only partially correct the strong effect of employer establishment size.

Concordance between ANSI occupational back injury codes and claim form diagnoses and a lower bound estimate of the fraction associated with disc displacement/herniation

The current BLS Annual Survey of Occupational Illnesses and Injuries and several recent analyses of factors affecting missed worktime in occupational back injuries rely on ANSI-based injury codes derived from injury narratives to classify occupational injuries and estimate incidence and outcome. No population-based studies of the concordance between back injury codes and clinical diagnoses have been reported. Back injury cases were identified in two large work-injured populations totaling almost 80,000 cases in the states of Michigan and Minnesota. In both populations, cases had been coded by the single nature-of-injury and part-of-body-injured codes assigned by an ANSI-based injury-coding system and by as many as four (Michigan) or three (Minnesota) clinical diagnoses according to the International Classification of Diseases-Clinical Modification, 9th Revision. Concordance was measured by the sensitivity and predictive value positive (PVP, aka PV+ or PPA) of the injury coding scheme for related diagnostic groups. We also used an algorithm based on the limited clinical information available to corroborate the diagnosis of displaced/herniated disc for cases that underwent spinal surgery. Cases identified by the algorithm were then used to obtain a lower bound estimate of the fraction with disc injury. The injury coding scheme had PVPs of 82.9-90.1% and overall sensitivities of 69.7-75.9%. Sensitivities for individual diagnostic groups show that their distribution in ANSI-coded injury groups is skewed slightly toward cases with sprain and disc displacement/herniation, but these shifts are modest. The lower bound estimate of the fraction of cases with disc displacement/herniation in a population of cases with back injuries producing at least 1 day of missed worktime is 5.8%. The demographic comparisons indicate that, as the time between injury and cohort ascertainment increases during the first 8 days of missed worktime following injury, the proportion of younger workers in an injury cohort decreases. The relationship between increasing age and increasing missed worktime disability, reported in various outcome studies, is also present during the first few days following injury. The use of ANSI injury codes underestimates the contribution of back injuries to missed worktime because 24-30% of cases are missed by the ANSI coding system. However, the distribution of diagnostic groups in the injury-coded groups approximates that observed with all diagnosed cases and supports the use of such data to study outcome. Our estimate, and one from Quebec, suggest that disc displacement/herniation occurs more frequently in the subset of occupational back injuries compared to the set of back injuries from all sources.

Establishment size and risk of occupational injury

For many years, the annual survey of occupational injuries and illnesses by the Federal Bureau of Labor Statistics (BLS) has consistently reported, without explanation, that injury rates in the smaller establishments (< 50 employees) are substantially lower than those for midsize establishments (100-499 employees). Also during those years, a remarkable increase has been reported in the injury rate in large companies, following the imposition of stiff fines for failure to keep required injury records. The rate patterns are identical for Michigan and the country in general. We investigated possible causes for lower injury rates in small establishments since such rates are inconsistent with reports of higher fatality rates in small establishments in the mining, construction, manufacturing, and transportation industries and higher, or at least comparable, injury rates for small establishments in the mining industry. They are also inconsistent with increased turnover and decreased availability of occupational safety services in small companies. Moreover, injury severity, as measured by missed worktime, is greater for workers in small establishments. We investigated the possibility that interactions of workforce or injury characteristics with establishment size could explain the rate differences. We also reviewed the available literature to see whether differences in labor turnover rates could explain the BLS findings. Graphical and statistical analyses of the 1988 CPS Annual Demographic File, a sample of employed persons in the U.S. workforce, failed to identify any associations between workforce characteristics and enterprise size that would explain the lower rates. Similarly, graphical and statistical analyses of all Michigan workers incurring a compensable injury in 1986 failed to indicate any associations between injury characteristics and establishment size that would explain the lower rates. The potential role of labor turnover on the injury rate was analyzed from data in the literature on turnover rate by establishment size and risk of injury by time on the job. None of these analyses explains the lower injury rates reported for small establishments. This leaves underreporting of injuries from small establishments as a substantial possibility. If small establishments were subject to the same injury incidence rates as midsize establishments, then the 1986 survey for Michigan may have missed as many as 54,000 injuries (and far more nationally). We suggest that BLS undertake methodological studies to validate the completeness of reporting from small establishments.

Current methods of estimating severity for occupational injuries and illnesses: data from the 1986 Michigan Comprehensive Compensable Injury and Illness Database

National and state estimates of the severity of occupational injuries and illnesses (severity = lost work time = missed work days+restricted work days) have come from the annual Survey of Occupational Injuries and Illnesses (Survey) produced by the U.S. Bureau of Labor Statistics. However, we show that the Survey practice of collecting injury information soon after the accident year reduces substantially the accuracy of missed work day estimates, which constitute 85.3% of the Survey lost work time estimate. To develop an independent estimate of missed work days, the research team created the Michigan Comprehensive Compensable Occupational Injury Database (Michigan Database) by linking state files with injury characteristics to files with workers' compensation information for injuries occurring in 1986. The measure of missed work time (days, weeks, or years) is the cumulative duration of compensation from the "date disability commenced," noted on the first payment form, through follow-up to March 1, 1990. Cumulative missed work time has been calculated or estimated for 72,057 injured workers, more than 97% of the 73,609 Michigan workers with compensable occupational injuries in 1986 identified through the close of the study. Our "best" estimate of missed work days, to follow-up, attributable to both fatal and nonfatal compensable occupational injuries and illnesses is 7,518,784, a figure four times that reported for Michigan by the Survey. When insurance industry data on disbursements are also considered, the estimate of missed work days increases to 8,919,079, a figure 4.75 times that reported by the Survey. When insurance data on reserves for future payments are also considered, the estimate of missed work days increases to 16,103,398, a figure 8.58-fold greater than that obtained for Michigan in the Survey. The Michigan data suggest that the national Survey may have failed to identify almost 373 million of 421 million missed work days in the private sector that have resulted, or will result, from 1986 occupational injuries. The present federal/state system for estimating occupational injury severity by measuring lost work days seriously underestimates the magnitude of the problem. The current policy of obtaining incidence and severity data from the same Survey should be reconsidered. We recommend that national estimates of injury severity be obtained from representative states by using state compensation data and that such estimates be used to evaluate current prevention and rehabilitation strategies. The redesigned occupational safety and health Survey (ROSH Survey) should be revised to permit linkage to compensation data.

Classical and El Tor cholera: a clinical comparison

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Clinical and physiological observations during an epidemic outbreak of non-vibrio cholera-like disease in Calcutta

During March through June 1964, an epidemic of acute non-vibrio diarrhoeal disease, closely simulating cholera, occurred in Calcutta. To clarify the etiology and pathophysiology and improve the therapy of this illness, bacteriological and metabolic studies were performed on 145 consecutive hypotensive adult male patients admitted with acute diarrhoeal disease to the Calcutta Infectious Disease Hospital. Bacteriological and serological studies clearly demonstrated that the majority of patients with acute diarrhoeal disease admitted during this period of time were not suffering from V. cholerae infection; no known pathogen could be recovered from 86% of such patients. Biochemical studies indicated that, in contrast to the findings in cholera, factors other than saline depletion contributed to hypotension in many of the patients with non-vibrio diarrhoeal disease. Although the majority of the acute diarrhoeal patients responded well to the 2: 1 saline: lactate regimen which is consistently successful in treating adult cholera patients, six of the non-cholera patients required prolonged administration of vasopressor drugs as an adjunct to fluid and electrolyte repletion therapy.