Oliver Wirth

When workplace safety depends on behavior change: Topics for behavioral safety research

INTRODUCTION Comprehensive interventions that address public-health concerns invariably include behavior-change strategies. In occupational safety and health, behavioral safety is an approach designed to improve safety performance directly through peer observations of safe behaviors, goal setting, performance feedback, and celebrations or incentives for reaching safety goals. Although the basic components of behavioral safety processes have been studied and widely documented, the current safety literature reveals several gaps in knowledge. These gaps are associated mostly with wide practice variations among the common process elements and uncertainty about the influence of organizational and other external factors. IMPACT TO INDUSTRY A major objective of this paper was to highlight not only key topic areas that warrant further research, but also to propose a list of research questions that are tied to uncertainties about various intervention practices. If only a portion of these topic areas and research questions are addressed through systematic reviews, field interventions, surveys, and laboratory-based studies, then the knowledge gained will significantly improve the delivery and effectiveness of behavioral safety interventions and thus their impact on worker health and safety.

Mitochondrial dysfunction and loss of Parkinson's disease-linked proteins contribute to neurotoxicity of manganese-containing welding fumes

Welding generates complex metal aerosols, inhalation of which is linked to adverse health effects among welders. An important health concern of welding fume (WF) exposure is neurological dysfunction akin to Parkinsons disease (PD), thought to be mediated by manganese (Mn) in the fumes. Also, there is a proposition that welding might accelerate the onset of PD. Our recent findings link the presence of Mn in the WF with dopaminergic neurotoxicity seen in rats exposed to manual metal arc-hard surfacing (MMA-HS) or gas metal arc-mild steel (GMA-MS) fumes. To elucidate the molecular mechanisms further, we investigated the association of PD-linked (Park) genes and mitochondrial function in causing dopaminergic abnormality. Repeated instillations of the two fumes at doses that mimic ∼1 to 5 yr of worker exposure resulted in selective brain accumulation of Mn. This accumulation caused impairment of mitochondrial function and loss of tyrosine hydroxylase (TH) protein, indicative of dopaminergic injury. A fascinating finding was the altered expression of Parkin (Park2), Uchl1 (Park5), and Dj1 (Park7) proteins in dopaminergic brain areas. A similar regimen of manganese chloride (MnCl(2)) also caused extensive loss of striatal TH, mitochondrial electron transport components, and Park proteins. As mutations in PARK genes have been linked to early-onset PD in humans, and because welding is implicated as a risk factor for parkinsonism, PARK genes might play a critical role in WF-mediated dopaminergic dysfunction. Whether these molecular alterations culminate in neurobehavioral and neuropathological deficits reminiscent of PD remains to be ascertained.

Increased Oxidant Activity Mediates Vascular Dysfunction in Vibration Injury

Occupational exposure to hand-operated vibrating tools causes a spectrum of pathological changes in the vascular, neurological, and musculoskeletal systems described as the hand-arm vibration syndrome (HAVS). Experiments were performed to determine the effects of acute vibration on the function of digital arteries. Rats paws were exposed to a vibrating platform (4 h, 125 Hz, constant acceleration of 49 m/s2 root mean squared), and digital artery function was assessed subsequently in vitro using a pressure myograph system. Constriction to phenylephrine or 5-hydroxytryptamine was reduced in digital arteries from vibrated paws. However, after endothelium denudation, constriction to the agonists was no longer impaired in vibrated arteries. Inhibition of nitric-oxide synthase (NOS) with Nω-nitro-l-arginine methyl ester (l-NAME) increased constriction to phenylephrine or 5-hydroxytryptamine in vibrated but not control arteries and abolished the vibration-induced depression in constrictor responses. However, nitric oxide (NO) activity, determined using the NO-sensitive probe 4-amino-5-methylamino-2′, 7′-difluorofluorescein, was reduced in vibrated compared with control arteries. Endogenous levels of reactive oxygen species (ROS), determined using the ROS-sensitive probe 5-(and 6)-chloromethyl-2′,7′-dichlorodihydro-fluorescein, were increased in vibrated compared with control arteries. The increased ROS levels were abolished by l-NAME or by catalase, which degrades extracellular hydrogen peroxide. Catalase also increased constriction to phenylephrine or 5-hydroxytryptamine in vibrated but not control arteries and abolished the vibration-induced depression in constrictor responses. The results suggest that acute vibration causes vascular dysfunction in digital arteries by increasing ROS levels, which is probably mediated by uncoupling of endothelial NOS. Therefore, therapeutic strategies to inhibit ROS or augment NO activity may be beneficial in HAVS.

INTERVAL SAMPLING METHODS AND MEASUREMENT ERROR: A COMPUTER SIMULATION

A simulation study was conducted to provide a more thorough account of measurement error associated with interval sampling methods. A computer program simulated the application of momentary time sampling, partial-interval recording, and whole-interval recording methods on target events randomly distributed across an observation period. The simulation yielded measures of error for multiple combinations of observation period, interval duration, event duration, and cumulative event duration. The simulations were conducted up to 100 times to yield measures of error variability. Although the present simulation confirmed some previously reported characteristics of interval sampling methods, it also revealed many new findings that pertain to each methods inherent strengths and weaknesses. The analysis and resulting error tables can help guide the selection of the most appropriate sampling method for observation-based behavioral assessments.

Acute vibration reduces Aβ nerve fiber sensitivity and alters gene expression in the ventral tail nerves of rats

Long‐term occupational exposure to hand–arm vibration can result in a permanent reduction in tactile sensitivity in exposed fingers and hands. Little is known about how vibration causes this reduction in sensitivity, and currently no testing procedures have been developed to monitor changes in sensory perception during ongoing exposures. We used a rat‐tail model of hand–arm vibration syndrome (HAVS) to determine whether changes in sensory nerve function could be detected after acute exposure to vibration. Nerve function was assessed using the current perception threshold (CPT) method. We also determined whether changes in nerve function were associated with changes in gene transcription. Our results demonstrate that the CPT method can be used to assess sensory nerve function repeatedly in rats and can detect transient decreases in the sensitivity of Aβ nerve fibers caused by acute exposure to vibration. This decrease in Aβ fiber sensitivity was associated with a reduction in expression of nitric oxide synthase‐1, and a modest increase in calcitonin gene–related peptide transcript levels in tail nerves 24 h after vibration exposure. These transient changes in sensory perception and transcript levels induced by acute vibration exposure may be indicators of more prolonged changes in peripheral nerve physiology. Muscle Nerve, 2007

Texting while driving as impulsive choice: A behavioral economic analysis

The goal of the present study was to examine the utility of a behavioral economic analysis to investigate the role of delay discounting in texting while driving. A sample of 147 college students completed a survey to assess how frequently they send and read text messages while driving. Based on this information, students were assigned to one of two groups: 19 students who frequently text while driving and 19 matched-control students who infrequently text while driving but were similar in gender, age, years of education, and years driving. The groups were compared on the extent to which they discounted, or devalued, delayed hypothetical monetary rewards using a delay-discounting task. In this task, students made repeated choices between

Discounting the value of safety: Effects of perceived risk and effort

1000 available after a delay (ranging from 1 week to 10 years) and an equal or lesser amount of money available immediately. The results show that the students who frequently text while driving discounted delayed rewards at a greater rate than the matched control students. The study supports the conclusions that texting while driving is fundamentally an impulsive choice made by drivers, and that a behavioral economic approach may be a useful research tool for investigating the decision-making processes underlying risky behaviors.

A revised taxonomy of assistance animals

INTRODUCTION Although falls from heights remain the most prevalent cause of fatalities in the construction industry, factors impacting safety-related choices associated with work at heights are not completely understood. Better tools are needed to identify and study the factors influencing safety-related choices and decision making. METHOD Using a computer-based task within a behavioral economics paradigm, college students were presented a choice between two hypothetical scenarios that differed in working height and effort associated with retrieving and donning a safety harness. Participants were instructed to choose the scenario in which they were more likely to wear the safety harness. Based on choice patterns, switch points were identified, indicating when the perceived risk in both scenarios was equivalent. RESULTS Switch points were a systematic function of working height and effort, and the quantified relation between perceived risk and effort was described well by a hyperbolic equation. CONCLUSION Choice patterns revealed that the perceived risk of working at heights decreased as the effort to retrieve and don a safety harness increased. IMPACT ON INDUSTRY Results contribute to the development of computer-based procedure for assessing risk discounting within a behavioral economics framework. Such a procedure can be used as a research tool to study factors that influence safety-related decision making with a goal of informing more effective prevention and intervention strategies.

A behavioral economic analysis of texting while driving: Delay discounting processes.

The use of animals in various assistive, therapeutic, and emotional support roles has contributed to the uncoordinated expansion of labels used to distinguish these animals. To address the inconsistent vocabulary and confusion, this article proposes a concise taxonomy for classifying assistance animals. Several factors were identified to differentiate categories, including (1) whether the animal performs work or tasks related to an individuals disability; (2) the typical level of skill required by the animal performing the work or task; (3) whether the animal is used by public service, military, or healthcare professionals; (4) whether training certifications or standards are available; and (5) the existence of legal public access protections for the animal and handler. Acknowledging that some category labels have already been widely accepted or codified, six functional categories were identified: (1) service animal; (2) public service animal; (3) therapy animal; (4) visitation animal; (5) sporting, recreational, or agricultural animal; and (6) support animal. This taxonomy provides a clear vocabulary for use by consumers, professionals working in the field, researchers, policy makers, and regulatory agencies.

Texting while driving, executive function, and impulsivity in college students

The purpose of the present study was to examine an impulsive decision-making process underlying texting while driving from a behavioral economic perspective. A sample of 108 college students completed a novel discounting task that presented participants with a hypothetical scenario in which, after receiving a text message while driving, they rated the likelihood of replying to a text message immediately versus waiting to reply for a specific period of time. Participants also completed a delay discounting task in which they made repeated hypothetical choices between obtaining a larger amount of money available after a delay and an equal or lesser amount of money available immediately. The results show that the duration of the delay is a critical variable that strongly determines whether participants choose to wait to reply to a text message, and that the decrease in the likelihood of waiting as a function of delay is best described by a hyperbolic delay discounting function. The results also show that participants who self-reported higher frequency of texting while driving discounted the opportunity to reply to a text message at greater rates, whereas there was no relation between the rates of discounting of hypothetical monetary rewards and the frequency of texting while driving. The results support the conclusion that texting while driving is fundamentally an impulsive choice.