Roger L. McCarthy

Risk and effectiveness criteria for using on-product warnings

A variety of potential hazards can be identified for nearly any consumer product, often more than can be practically or effectively addressed with warning labels. Published standards and guidelines for warnings do not offer a reasonable basis for limiting the number and length of warning labels. This paper proposes criteria for the use and design of warning labels based on effectiveness research, accident data, and product-associated risk.

Warnings on Consumer Products: Objective Criteria for their use

Consumer product warnings, often placards, buzzers, etc., are information displays that attempt to influence user behavior through the information presented. A review and background of warnings is presented. Assumptions underlying their employment and the lack of scientific validation of their effectiveness are discussed. Quantitative criteria are proposed for the use of warnings based on risk analysis. Examples of such analysis are presented. The limited information processing capability of man dictates that warnings be reserved for significant risks in the context of the products use, environment, and risks from other products. Contraindications for use of warnings are discussed.

Safety Information Presentation: Factors Influencing the Potential for Changing Behavior

Studies of several on-product warnings and product safety messages provide evidence that on-product warnings have not been effective in preventing injuries. However, there are examples of information presentations that, in conjunction with other factors, do modify human behavior. Some of these examples are safety-related. The authors examine the factors that influence the potential for changing human behavior and their implications for safety information about consumer products.

Measured Impact of a Mandated Warning on User Behavior

Two groups of expectant first-time mothers were asked to examine an automobile infant restraint and its instruction label, then to install the restraint in an automobile. The label for one group was presented in a warning format, as now required by federal regulation, while the label for the other group was not. Error rates were higher for the warning-label group, although the difference was not statistically significant. Most subjects rated the labels as “Good” or “Very Good”, whether or not they installed the restraints correctly. Results illustrate that, in some situations, clear and direct instructions can be at least as effective as a warning in eliciting the desired behavior, and that subjective ratings of labels are not necessarily valid predictors of impact on behavior.

Evaluation of Potential Safety Modifications by Review of Accident Reports

Analysis of accident data for consumer products can be used to identify accident modes and to aid in decisions about the feasibility of safety interventions for reducing risk. Decisions based upon a large accident data set, rather than upon a single accident, are much more likely to address important problems and to avoid creating negative consequences (e.g., increases in other kinds of accidents, loss in product utility). This paper describes the application of accident report analysis to a proposed safety intervention for all-terrain vehicles (ATVs). In order to evaluate the suggested use of conspicuity flags as standard equipment on all ATVs to prevent collision-related accidents, we reviewed 287 operating-ATV-associated “In-Depth Investigations” (conducted by the Consumer Product Safety Commission for ATV-associated injuries reported by the National Electronic Injury Surveillance System during a 2.5 month period in 1985). It was found that flags could have influenced only a very small portion of ATV injuries at best, and might even have a null or negative net impact when problems are considered. Thus, required usage of flags would be inappropriate for most riding environments.

Present and future safety challenges of computer control

Computer-based control systems have gradually assumed control of the national energy consumption. Computers have gone from control of a few percent of the nations total prime-mover (engine) horsepower to an overwhelming majority through application to vehicle engines, which are 95% of total national prime-mover horsepower. If an accident is defined as an undesired release of energy causing injury or loss, then unintended computer-control operations or malfunction could affect the national safety picture. As computer-controlled systems move from military/space applications to mass consumer products, these systems are subject to abuse and operating conditions that tax any program design. Such systems will enter the national product-liability situation, where computer-system designs will be judged not only on their ability to operate as intended, but on their ability to compensate safely for foreseeable misuse. Present and future problems of computer control are discussed in this context.<<ETX>>

Average Operator Inaction Characteristics with Lever Controls — Study of the Column Mounted Gear Selector Lever

Sixty drivers executed 1800 automotive transmission shifts from DRIVE to PARK. These shifts were performed in a total of six vehicles. Among analoq data recorded during each shift are longitudinal (pull) and rotational forces and rotational position of the lever. Analysis reveals that drivers typically impact the mechanical stop associated with PARK position with approximately one and one-half times the minimum force required to complete the shift. Shifts to PARK are completed in an average of 0.58 seconds, and an additional 0.83 seconds is spent continuing to apply force to the lever after PARK position is achieved. Most (80%) shifts are executed without regard for intervening detents. Those drivers who show hesitation in movement typically hesitate for 50 milliseconds. Whether a driver shifts continuously or with shortduration hesitation appears to be driver style or insert plate impact, independent of vehicle.

Analysis of Accident Data and Fatal Risk for Occupational Use of Extension Ladders

This paper presents the results of analyses of injury and fatality accidents associated with the occupational use of metal extension ladders. Data contained in seven different data bases differing in geographic representation and level of severity of injury were analyzed to identify the type of accidents that occur and their frequency. In addition, the risks of fatality and of electrocution fatality associated with occupational use of extension ladders were estimated and compared with the fatal risk for various occupations. The overall fatal risk for extension ladder use by workers is less than the overall fatality risk for the construction industry.

Child Resistant Closure Performance Aging Study

Child poisoning has been dramatically reduced by the introduction of child resistant (CR) closures on some common home chemicals and pharmaceuticals. However, “child resistance” (often mischaracterized as “child proof”) is a mechanical design property that is neither well understood nor supported by a body of theory, nor that can be specified from engineering first principles. Instead, child resistance is an empirically developed and verified closure mechanical property derived from closure testing with child subjects, as specified by regulations under the Poison Prevention Packing Act (PPPA). The authors report their longitudinal study of a specific Type III CR closure over a period of decades made with materials from different suppliers over time and using different injection molding tools. The study examines if the property of “child resistance” persisted and if it correlated with the mechanical specifications of the closure actually measured and controlled in the closure manufacturing process. This data is combined with the authors’ mechanical measurements of closure performance. Child resistance, being a complex, empirically tested property, cannot be regularly tested in the normal manufacturing environment. Despite minor manufacturing process and specification changes, if the mechanical specifications are appropriate (e.g. not intended to produce changes in CR mechanical properties) and with adequate quality control, the property of child resistance persists.Copyright

Ergonomic Analysis of Extension Ladders

Although the most serious accident mode associated with extension ladder use has always been “falling off the ladder” there has been increasing attention, recently, on “contact with electric current” or electrocution accidents primarily with aluminum ladders. The U.S. Consumer Product Safety Commission (CPSC) has made several recommendations to address this problem from a technical approach. They have proposed insulating and/or isolating the ladder electrically or replacing it with a fiberglass ladder. Long extension ladders are heavy, and proposed recommendations by the CPSC to make aluminum extension ladders nonconductive include replacing them with fiberglass extension ladders, which will definitely result in a heavier ladder. A heavier ladder has implications for the characteristics of the user population and for types of injury patterns. Occupational accident data show that ladder associated accidents directly related to ladder weight, such as overexertion, are more likely. If ladder weight were increased for example, by using exclusively nonconductive fiberglass ladders, overexertion would be a greater concern. A statics model was developed that uses a variety of variables relevant to the ladder erection process to determine the amount of force required of users to erect various types of extension ladders. Anthropometric data on the male and the female adult population were compared to the ladder user requirements. The percentages of males and of females capable of erecting 12.2-meter (40-foot) extension ladders were determined. Only three percent of female adults have the strength and reach height to erect 12.2-meter (40-foot) fiberglass extension ladders. Mandated use of 12.2-meter (40-foot) fiberglass extension ladders would greatly restrict the numbers of females who could perform jobs requiring the use of such ladders.