A prospective study of back belts for prevention of back pain and injury

CONTEXT

Despite scientific uncertainties about effectiveness, wearing back belts in the hopes of preventing costly and disabling low back injury in employees is becoming common in the workplace.

OBJECTIVE

To evaluate the effectiveness of using back belts in reducing back injury claims and low back pain.

DESIGN AND SETTING

Prospective cohort study. From April 1996 through April 1998, we identified material-handling employees in 160 new retail merchandise stores (89 required back belt use; 71 had voluntary back belt use) in 30 states (from New Hampshire to Michigan in the north and from Florida to Texas in the south); data collection ended December 1998, median follow-up was 6(1/2) months.

PARTICIPANTS

A referred sample of 13,873 material handling employees provided 9377 baseline interviews and 6311 (67%) follow-up interviews; 206 (1.4%) refused baseline interview.

MAIN OUTCOME MEASURES

Incidence rate of material-handling back injury workers' compensation claims and 6-month incidence rate of self-reported low back pain.

RESULTS

Neither frequent back belt use nor a belt-requirement store policy was significantly associated with back injury claim rates or self-reported back pain. Rate ratios comparing back injury claims of those who reported wearing back belts usually every day and once or twice a week vs those who reported wearing belts never or once or twice a month were 1.22 (95% confidence interval [CI], 0.87-1.70) and 0.95 (95% CI, 0.56-1.59), respectively. The respective odds ratios for low back pain incidence were 0.97 (95% CI, 0.83-1.13) and 0.92 (95% CI, 0.73-1.16).

CONCLUSIONS

In the largest prospective cohort study of back belt use, adjusted for multiple individual risk factors, neither frequent back belt use nor a store policy that required belt use was associated with reduced incidence of back injury claims or low back pain. JAMA. 2000;284:2727-2732.

A novel nemaline myopathy in the Amish caused by a mutation in troponin T1

The nemaline myopathies are characterized by weakness and eosinophilic, rodlike (nemaline) inclusions in muscle fibers. Amish nemaline myopathy is a form of nemaline myopathy common among the Old Order Amish. In the first months of life, affected infants have tremors with hypotonia and mild contractures of the shoulders and hips. Progressive worsening of the proximal contractures, weakness, and a pectus carinatum deformity develop before the children die of respiratory insufficiency, usually in the second year. The disorder has an incidence of approximately 1 in 500 among the Amish, and it is inherited in an autosomal recessive pattern. Using a genealogy database, automated pedigree software, and linkage analysis of DNA samples from four sibships, we identified an approximately 2-cM interval on chromosome 19q13.4 that was homozygous in all affected individuals. The gene for the sarcomeric thin-filament protein, slow skeletal muscle troponin T (TNNT1), maps to this interval and was sequenced. We identified a stop codon in exon 11, predicted to truncate the protein at amino acid 179, which segregates with the disease. We conclude that Amish nemaline myopathy is a distinct, heritable, myopathic disorder caused by a mutation in TNNT1.

Determination of whole-body rotenone residues in the brown tree snake (Boiga irregularis)

The brown tree snake (Boiga irregularis) is an introduced pest in Guam, responsible for extensive agricultural damage, the extinction of several bird species, and severe and frequent electrical power outages. Rotenone, a naturally occurring pesticide, has been investigated as a possible chemical control agent. An analytical method was developed to assess whole body rotenone residues ranging in concentration from 0.035 to 250 microg g(-)(1) in snakes. The method employed ethyl acetate extraction of 2 g samples of cryogenically frozen, pulverized snakes, followed by silica and Florisil solid-phase extraction cleanup. Extract analysis was performed using a high-performance liquid chromatography system employing a cyanopropyl analytical column. Tissues fortified to concentrations of 0.035, 4.82, and 250 microg g(-)(1) yielded analyte recoveries of 85.1, 85.6, and 83.5%, respectively. The linear response of rotenone standard solutions was assessed from 0. 025 to 0.25 microg mL(-)(1) (r(2) = 0.9968) and from 0.250 to 125 microg mL(-)(1) (r(2) = 0.9999). The method was simple, rugged, and reliable.

Development and testing of seven new synthetic coyote attractants

Available evidence indicates that effective coyote attractants are blends of volatile substances. Typically, attractants are a combination of biological substances such as fermented glandular materials, urines, and rotted meats. Although effective, these attractants have several distinct disadvantages. Among these is the possibility that they are unnecessarily complex and variable and, thus, difficult to replicate from one batch to the next. Although attractants containing a few reagent grade materials are available, the chemicals selected and their concentrations are not derived from actual attractants. For this reason, commercially available coyote attractants were analyzed with the intention of developing relatively simple synthetic alternatives. Purge and trap headspace analysis with gas chromatography/mass selective detection was employed to identify the volatile components of known conventional and synthetic attractants. All identified compounds were grouped according to chemical functionality, and one compound from each functional group was chosen to represent the group. Using only these representative compounds, seven synthetic attractants were formulated. Bioassays with captive coyotes (Canis latrans) were conducted to compare behavioral responses elicited by the seven new attractants, a currently available synthetic attractant, and a control. The results indicated that the attractants elicited significantly different behavioral profiles.

Expanded analysis of injury mortality among unionized construction workers

BACKGROUND

To evaluate the utility of expanding the number and precision of injury categories used in previous occupational mortality studies, this study reanalyzed data from four previous studies of unionized construction workers (construction laborers, ironworkers, sheet metal workers, and operating engineers), by expanding the number of injury categories from 6 to 33.

METHODS

Proportionate mortality ratios (PMRs) were computed using the distribution of deaths from the National Occupational Mortality Surveillance System, a mortality surveillance system from 28 states, as a comparison. A blue collar comparison group was also used in additional analyses to adjust for socioeconomic and other factors.

RESULTS

This reanalysis identified significantly elevated PMRs in at least one of the four worker groups for falls, motor vehicle crashes, machinery incidents, electrocutions, being struck by falling objects, being struck by flying objects, explosions, suffocation, and water transport incidents. Limiting the comparison population to deaths among blue collar workers did not change the results substantially.

CONCLUSIONS

This study demonstrates that increasing the precision of categories of death from injury routinely used in mortality studies will provide improved information to guide prevention. Am. J. Ind. Med. 37:364-373, 2000. Published 2000 Wiley-Liss, Inc.

Fatal occupational injuries associated with forklifts, United States, 1980-1994

BACKGROUND

This paper describes deaths of American workers involving forklifts during the 15-year period from January 1, 1980 to December 31, 1994.

METHODS

Death certificate data were obtained from the National Institute for Occupational Safety and Health's (NIOSH's) National Traumatic Occupational Fatality (NTOF) surveillance system. The narrative fields on the death certificate were searched for keywords indicating that a powered industrial vehicle (PIV) or forklift was involved in the death. This study examined the circumstances of the forklift-related deaths, the nature of the injury, and the decedent's age, gender, race, occupation, and industry. Average annual employment data from the Bureau of the Census were used to calculate civilian fatality rates by age, gender, industry, and occupation.

RESULTS

A total of 1,021 deaths were identified. The average age of the fatally injured worker was 38 years; the 1,021 forklift-related deaths resulted in a total of 27,505 years of productive life lost. The three most common circumstances of the fatalities were forklift overturns (22%), pedestrian struck by forklifts (20%), and worker crushed by forklift (16%). The greatest proportion of the fatalities (37%) occurred to workers in Manufacturing, followed by Transportation, Communication, and Public Utilities, (TCPU), (17%), Construction (16%), Wholesale Trade (8%), and Agriculture, Forestry, and Fishing (AFF) (7%). The highest forklift-related fatality rates per ten million workers occurred among transport operatives (34.0) and laborers (32.0).

CONCLUSIONS

Many of the fatalities resulting from forklift "overturns" might have been prevented if the operator had been restrained with a lap/shoulder belt. Careful consideration should be given to separating pedestrian and forklift traffic, and restricting the use of forklifts near time clocks, exits, and other areas where large numbers of pedestrians pass through an area in a short time. Additionally, systematic traffic control, including rules for pedestrian and forklift traffic, will be necessary to reduce the enormous injury and death toll associated with forklifts. Am. J. Ind. Med. 36:504-512, 1999. Published 1999 Wiley-Liss, Inc.

Determination of propionylpromazine hydrochloride in formulation matrixes using reversed-phase ion-pair small bore liquid chromatography

Propionylpromazine hydrochloride (PPZHCl) has been investigated for use with leghold traps to reduce the amount of self-inflicted trauma experienced by animals restrained by these traps. Three types of PPZHCl formulations made with Karo dark syrup, K-Y Jelly, and Vaseline were used in 2 types of tranquilizer trap devices (TTDs). A reversed-phase ion-pair liquid chromatography (LC) method using a small bore C18 column was used to: (1) determine the purity of the PPZHCl material used in these formulations, and (2) to determine the resulting PPZHCl content of each formulation. Analyte quantitation was done using UV absorption at 280 nm. Regression analysis of calibration standard solutions indicated a linear and directly proportional relationship between analyte response and PPZHCl concentration over the range evaluated. Recovery data from: (1) Vaseline formulations containing 38.8, 16.2, and 8.78% PPZHCl were 104, 92.9, and 90.2%, respectively, (2) Karo dark syrup formulations containing 26.5, 18.1, and 10.3% PPZHCl were 97.7, 99.3, and 106%, respectively, and (3) K-Y Jelly formulations containing 33.0, 23.5, and 13.4% PPZHCl were 100, 99.4, and 88.7%, respectively. The relative standard deviation (RSD) values from triplicate analysis of these formulations ranged from 0.7 to 6.7%. The PPZHCl content from 9 manufactured TTDs, 3 for each formulation type, were analyzed in triplicate and produced RSD values ranging from 0.7-6.8%. These results indicate that the formulation extraction presented could be used to evaluate the PPZHCl content in TTDs prior to field use. The use of a small bore LC column reduced the amount of solvents consumed and hazardous waste generated, compared to sample analysis that uses a more conventional analytical LC column.

Stabilization of the avicide 3-chloro-p-toluidine as the beta-cyclodextrin adduct

Stabilization of the avicide 3-chloro-p-toluidine (CPTH) on rice baits by pseudo latex polymeric coating and beta-cyclodextin inclusion was investigated. When CPTH-treated rice baits were exposed to sunlight, the CPTH formed colored compounds, which exacerbated problems with bait acceptance and efficacy. Fluidized bed coating with controlled-release polymeric psuedo latexes (RS, RL, NE) reduced CPTH loss but did not eliminate color formation. Enteric pseudo latex coatings (CAP and 4110) gave mixed results. Coating 4110 reduced CPTH loss but still allowed color formation, whereas CAP allowed more CPTH loss than any other coating as well as increased color formation. Inclusion in beta-cyclodextrin (molar ratio 1:1) led to enhanced retention of CPTH and minimal color formation. The CPT/beta-cyclodextrin adduct increased retention of CPTH from 43 to 70% upon simulated weathering. The retention was independent of the adhesives used for attachment.

Quantitation of pyrethrum residues in brown tree snakes

A reversed-phase solid-phase extraction-gas chromatography (SPE-GC)-electron capture detection method is developed to quantitate individual rethrin residues in pyrethrum-exposed brown tree snakes. Aliquots (6 g) of homogenized snake tissue are extracted with 10 mL acetonitrile. The rethrins are recovered from the acetonitrile extract and concentrated using C8 SPE. The rethrins are eluted from the SPE column with pentane, evaporated to near dryness, and reconstituted to 1 mL with 1-propanol. Individual rethrins are quantitated using GC analysis of the 1-propanol solution. Method limits of detection for rethrins range from 0.63 to 6.51 ng/g. The mean recovery for all rethrins is 70.8% with a standard deviation of 5.7%. This method is used to successfully quantitate incurred rethrin residues in pyrethrum-exposed brown tree snakes.

Reversed-phase ion-pair liquid chromatographic determination of chlorophacinone and diphacinone in steam-rolled oat baits and steam-rolled oat/wax baits

A reversed-phase ion-pair liquid chromatographic (LC) method was developed for analysis of steam-rolled oat (SRO) baits fortified with either chlorophacinone or diphacinone. Baits were prepared with and without paraffin wax. Chlorophacinone or diphacinone was extracted from wax-free SRO baits with 5 mM tetrabutylammonium phosphate methanolic ion-pairing solution. Wax baits were initially extracted with petroleum ether and then cleaned up by liquid extraction into methanolic ion-pairing solution containing 20% water. SRO extracts were analyzed with reversed-phase ion-pair LC. Chlorophacinone and diphacinone were quantified by UV absorption at 325 nm. Recoveries from SRO fortified with chlorophacinone at 25 and 150 micrograms/g were 90.7 and 90.8%, respectively, whereas for diphacinone at the same levels, recoveries were 93.5 and 92.3%, respectively. Recoveries from wax baits fortified at 25 and 75 micrograms/g chlorophacinone were 98.5 and 100%, respectively, whereas for diphacinone at the same levels, recoveries were 93.6 and 98.0%, respectively. Method limits of detection for chlorophacinone and diphacinone in SRO baits were estimated to be 1.0 and 0.76 micrograms/g, respectively. Method limits of detection for chlorophacinone and diphacinone in wax baits were estimated to be 4.2 and 2.8 micrograms/g, respectively.

Reversed-Phase Ion-Pair High-Performance Liquid Chromatographic Quantitation of Difethialone Residues in Whole-Body Rodents with Solid-Phase Extraction Cleanup

A reversed-phase ion-pair high-performance liquid chromatographic method was developed for the determination of difethialone residues in laboratory rats (Rattus norvegicus). Difethialone was extracted from rat tissue with chloroform/acetone/formic acid. The extracts were cleaned up by a solid-phase extraction (SPE) procedure using both silica and aminopropyl SPE sorbents, concentrated, and analyzed by reversed-phase ion-pair high-performance liquid chromatography. Difethialone was quantitated via ultraviolet absorbance at 262 nm. A surrogate compound, brodifacoum, was used to correct for method performance. The mean surrogate-corrected recoveries for whole ground rodent fortified at 0.2, 1.0, and 20 µg/g difethialone were 92.3 +/- 7.7, 84.8 +/- 6.6, and 90.2 +/- 3.1%, respectively. The method limit of detection was 0.054 µg/g.

Solid-phase extraction method for the quantitative analysis of organochlorine pesticides in wildlife urine

A gas chromatographic method for the analysis of nine organochlorine pesticides in wildlife urine is described. Reversed-phase solid-phase extraction is utilized to extract the organochlorine pesticides from urine. The pesticides are recovered by elution with hexane-ethyl ether (1:1) and quantified by gas chromatography with electron-capture detection. Method detection limits range from 1.4 to 2.7 micrograms/L. Mean recoveries for all pesticides are 90.6%.

Design and conduct of occupational injury intervention studies: a review of evaluation strategies

Occupational injuries continue to exact a great toll on American workers and their employers--the physical and financial costs are enormous. However, in the current political climate, few employers or regulatory agencies will implement injury prevention interventions without specific evidence of their effectiveness. This paper reviews the literature on the design, conduct, and evaluation of occupational injury interventions. Our review suggests that randomized controlled trials are rare and also notes that the quasi-experimental studies in the literature often use the weakest designs. We recommend a hierarchical approach to evaluating occupational injury interventions--beginning with qualitative studies, following up with simple quasi-experimental designs using historical controls, continuing with more elaborate quasi-experimental designs comparing different firms' experience, and, when necessary, implementing randomized controlled trials.

Two new oral chemical biomarkers for coyotes

Pentachlorobenzene (PeCB) and 1,2,3,4-tetrachlorobenzene (TeCB) were evaluated as oral chemical biomarkers when administered to coyotes (Canis latrans) during the period of 31 January to 10 August 1994. Three coyotes each received 100 mg of PeCB and three received 100 mg of TeCB, each in a mineral oil formulation. Three additional coyotes received only the mineral oil carrier. Muscle and adipose tissues, blood serum, and fecal samples were evaluated by capillary gas chromatography with electron capture detection for 120 days following administration. Residues of PeCB were detected in serum, feces, and adipose and muscle tissues for 120 days post-treatment; TeCB residues were detected in feces and serum at 1 and 8 days post-treatment and in adipose tissue at 30 days post-treatment. Residues of TeCB were not detected in muscle tissue at any point in the study.

Renal abnormalities and an altered inflammatory response in mice lacking cyclooxygenase II

Prostaglandins have wide-ranging effects in the body and are thought to be important mediators of inflammation. Cyclooxygenase (COX) plays a key regulatory role in prostaglandin synthesis, and occurs in both constitutive (COX-1) and inducible (COX-2) isoforms. COX-1 is thought to provide cytoprotective effects, whereas COX-2 is both inducible and the major isoform of inflammatory cells. Reduction of prostaglandin production by inhibition of cyclooxygenases appears to be the main mechanism of action of most non-steroidal anti-inflammatory drugs (NSAIDS). Here we present an animal model of COX-2 deficiency that was generated by gene targeting. Defects in null mice correlating with reduced viability included renal alterations, characteristic of renal dysplasia (100% penetrance), and cardiac fibrosis (50% penetrance). Female Cox-2-/- mice were infertile. COX-2 deficiency failed to alter inflammatory responses in several standard models, but striking mitigation of endotoxin-induced hepatocellular cytotoxicity was observed.

Occupational injury and stress

A literature search was conducted to identify studies that measured the relationship between stress and occupational injury. Studies that provided a quantitative measure of stress and occupational injury and a quantitative assessment of the relationship between these two factors were selected for this review. Twenty studies were identified, and all had P values of less than .05 or odds ratios ranging from .3 to 4.6. Twelve of 17 measures had odds ratios greater than 1.0. Several factors limit the generalizability of these results, however, and these include methodological differences in the assessment of stress and injury, study design, and limited representation of occupations.

Comparison of reversed-phase and ion-pair chromatography for the determination of strychnine in animal tissues

Ion-pair and reversed-phase high-performance liquid chromatography (HPLC) were evaluated for quantification of strychnine in mountain beaver tissues. Retention time shifts hindered strychnine quantification with both HPLC systems. Co-extracted free fatty acids released during storage formed ion-pairs with strychnine, resulting in increased retention by reversed-phase HPLC. Competition with co-extracted basic compounds is likely responsible for the decreased retention of strychnine by ion-pair HPLC. Following an acid-base clean-up, optimal results were obtained with reversed-phase HPLC. Ion-pair chromatography was then used for qualitative confirmation of strychnine residues.

Interleukin-8 receptor beta. The role of the carboxyl terminus in signal transduction

Two interleukin-8 (IL-8) receptors, alpha and beta, have been identified and cloned. Both receptors are thought to transduce signals by coupling to GTP-binding proteins. The aim of this study is to determine whether the carboxyl terminus (C') of IL-8 receptor beta (IL-8R beta) is involved in signaling in response to IL-8. We have constructed a number of IL-8R beta genes that encode truncated forms of the IL-8R beta. The deletions consisted of amino acids 349-355, 336-355, 325-355, and 317-355 (termed beta 2, beta 3, beta 4, and beta 5, respectively). 293 human embryonic kidney cells were transfected with the wild type IL-8R beta (beta 1) and with these mutants. Cells transfected with the mutated receptors expressed the receptors and bound IL-8 with the same high affinity as cells transfected with the wild type receptor. The capacity of the mutated receptors to convey functional signals was evaluated by comparing the chemotaxis index of cells expressing the C'-truncated receptors to the index of cells expressing the wild type receptor. The results indicate that while cells expressing beta 1, beta 2, beta 3, and beta 4 were chemoattracted in response to IL-8, cells expressing beta 5 did not migrate in response to IL-8 stimulation. Therefore, the data suggest that amino acids 317-324 are involved in signaling by IL-8R beta.

Social support for smoking cessation and abstinence: the Lung Health Study. Lung Health Study Research Group

This article evaluates the relationship of social support to smoking cessation and continued abstinence of 3923 men and women with mild to moderate airway obstruction in the Lung Health Study. At both the end of a 12-week group program and after 1 year, men but not women who were supported in quitting were more likely to be successful. Married status facilitated quitting but was less strongly related to long-term abstinence. Participants supported by an ex-smoker who had attended the group program with them were very likely not smoking after 1 year (men, 74.7%; women, 72.4%). Participants supported by a smoker were less than half as likely to have achieved abstinence after 1 year but still had cessation rates greater than 30%. The nature of these relationships has implications for the distinction between women and men in studies of social support and for intervention strategies. Support people should be included in cessation intervention programs. Spouse involvement, however, is more evidently useful for men than for women.

Effectiveness of behavioral safety belt interventions

A wide variety of approaches have been developed to promote safety belt use. This paper evaluates the relationship of types of behavioral safety belt programs to short- and long-term safety belt use rates. Five types of programs were examined: Law, Incentive, Education, Monitoring, and Prompt. Programs were generally effective in increasing use rates, with a median increase of 17.0% (95% CI = 13.4%, 20.1%). Program type differentially affected use rates, with Law and Incentive producing the highest increase in rates. Length of intervention and number of interventions within one program were not significantly related to use rates. Immediately after intervention ended, safety belt use declined but soon stabilized, with rates remaining significantly higher than baseline.

The efficacy of training for occupational injury control

Fifty years after reports that training enhances workplace safety began to appear in the literature, training continues to be considered a practical approach to injury prevention. However, data suggest that workplace training is not commonplace. Studies of the effectiveness of training are reviewed, and successful components of training programs are described.

Design and results of the initial intervention program for the Lung Health Study. The Lung Health Study Research Group

BACKGROUND

The design and results of the initial intervention program of the Lung Health Study are presented for 3,923 male and female participants. One of the major aims of this clinical trial was to achieve smoking cessation early in the study and to provide intensive follow-up procedures for maintaining abstinence. In addition, compliance with use of aerosolized inhalers (either placebo or active bronchodilator) would be necessary in order to achieve the trial goal of improved pulmonary function.

RESULTS

Eighty-eight percent of the special intervention participants attended the 4-month follow-up visit. Forty-six percent reported not smoking from quit day through the visit, and an additional 13% had stopped smoking at the end of 4 months, although they had not achieved abstinence since quit day. The aerosol inhaler compliance was self-reported at 81% at the 4-month visit. Validating the self-reports by weighing canisters reduced the "good" compliance rates to 66%.

CONCLUSIONS

The intensive behavioral program was effective in achieving high initial rates of smoking cessation and inhaler compliance. Use of nicotine gum appeared to be an effective adjunct to the multicomponent behavioral program. Smoking status does appear to be related to inhaler compliance among both men and women participants.

Structure and expression of neutrophil gelatinase cDNA. Identity with type IV collagenase from HT1080 cells

Neutrophils synthesize and store intracellularly a 92-kDa type IV collagenase (gelatinase), the primary structure of which is unknown. We designed a primer based on the highly conserved cysteine-switch region of metalloproteinases and employed the polymerase chain reaction to generate a probe of the human neutrophil gelatinase (HNG) gene. This probe was used to clone the cDNA encoding HNG by screening a chronic granulocytic leukemia cDNA library. In vitro translation of the cDNA-derived HNG mRNA yielded a major product of 78 kDa and smaller autolytically activated or degraded products, all of which were recognized by anti-HNG antibody. The HNG cDNA sequence is nearly identical to that encoding a 92-kDa gelatinase secreted by HT1080 cells. In addition, primer extension and S1 analysis reveal that the above two gelatinase transcripts have similar initiation sites. The HNG cDNA hybridized to a 2.8-kilobase mRNA from chronic granulocytic leukemia cells. HNG mRNA expression was absent from uninduced HL60 cells and from HL60 cells induced to granulocytic maturation with Me2SO. However, unlike other neutrophil secondary granule genes, HNG mRNA was detected in HL60 cells induced to monocytic maturation with 12-O-tetradecanoylphorbol 13-acetate. This suggests that the HNG gene may be subject to differential control pathways in two related but distinct hematopoietic lineages.

Correlation of messenger RNA levels with protein defects in specific granule deficiency

Neutrophil specific granule deficiency (SGD) is a rare congenital disorder of unknown cause associated with an impaired inflammatory response and an absence of neutrophil secondary granules. Reduced levels of several neutrophil proteins have led to the suggestion that the defect may lie at the level of transcription, a hypothesis that is supported by abnormally low levels of lactoferrin message in the bone marrow of two SGD patients. We have examined the level of seven granule protein RNAs in one SGD patient and have compared them with reported protein levels. We have found the RNA levels for all of these genes to be reduced in proportion to the decreased levels of their respective proteins. These data further support the hypothesis that the reduced protein levels reflect a defect in transcriptional control.