Based on estimates from the U.S. Consumer Product Safety Commission (CPSC), there were about 25,000 baby walker-related injuries treated annually in U.S. hospital emergency departments during the early 1990s. This amounted to about 8 injuries for every 1000 baby walkers in use. Most injuries resulted from falls down stairs. After CPSC initiated a regulatory proceeding in 1994, the CPSC staff worked with industry to address the stair-fall hazard. This cooperative effort resulted in requirements designed to prevent stair-fall injuries that became effective in 1997 as part of a revised voluntary safety standard. This study presents a retrospective benefit-cost analysis of the 1997 stair-fall requirements. The benefits were defined as the reduction in the costs of injuries resulting from the use of the safer walkers. The costs were defined as the additional resource costs associated with making baby walkers safer. The study found that the stair-fall requirements were highly effective in reducing the risk of stair-fall injury, and that the benefits of the requirements substantially exceeded the costs. The expected net benefits (i.e., benefits minus costs) amounted to an average of about $169 per walker, over the walker's expected product life. Given current U.S. sales of about 600,000 baby walkers annually, the present value of the expected net benefits associated with 1 year's production amounts to over $100 million annually. A sensitivity analysis showed that the major findings were robust with respect to variations in underlying assumptions.
Baby walkers are products that support preambulatory children and allow them to move by means of their feet. They generally consist of fabric seats with leg openings mounted to rigid plastic decks. The decks are attached to bases that have wheels or casters to make them mobile. Children using walkers usually range from about 6 to 15 months in age.
Based on estimates from the U.S. Consumer Product Safety Commission's (CPSC) National Electronic Injury Surveillance System (NEISS), the number of children under age 15 months who were treated in U.S. hospital emergency departments for injuries involving baby walkers rose from 16,400 in 1982 to 26,200 in 1991, an increase of 60% in 10 years. While some of the increase was related to the increased use of baby walkers, injury rates indexed by the number of walkers in use rose by 18%, from 6.8 injuries per 1000 walkers in use in 1982 to 8.0 per 1000 in 1991. During this time period, injuries resulting from falls down stairs (or, in some cases, falls from one floor level to another) represented the predominant baby walker hazard: about 75–80% of the walker injuries resulted from falls down stairs (Boudreault, 1995 and Shields and Smith, 2006).1
In 1994 the Commission initiated a regulatory proceeding to address the risk associated with stair-fall injuries (CPSC, 1994). At the same time, the Commission directed the staff to work with the American Society for Testing and Materials (ASTM) Walker Subcommittee, a voluntary standards group, to determine if requirements to prevent stair-fall injuries could be developed cooperatively with industry. These cooperative efforts led to the development of requirements (hereafter referred to as the “stair-fall requirements”) that were approved by ASTM in October 1996 (ASTM, 1996) and became effective in June 1997.
The stair-fall requirements include a performance test that simulates a child in a walker moving across the floor, through a doorway, and to a stairway. A dummy represents a child in the walker, and the walker is tested facing forward, backward, and sideways. The test uses a falling mass at the end of a rope extended over a pulley to pull the walker toward the edge of the test platform. If, during these tests, the walker passes through a 36-in. wide opening at the end of a test table and falls off the table, it fails the performance requirements. Alternatively, if the walker stops at the end of the test table, but any part of the walker extends over the table's edge, a tip-over test is performed. To conduct this test, a specified downward force is applied to the walker tray at a specified distance from its edge. The walker fails the performance requirements if it falls off the table during the tip-over test (ASTM, 1996, CPSC, 2002 and Kumagai, 2002). As described more fully below, manufacturers incorporated various design features into baby walkers to meet these requirements.
There appears to have been a high level of conformance to the stair-fall requirements of the voluntary standard. The major domestic manufacturers of baby walkers participated in the development of the requirements and have conformed to them from the outset. Major retailers have also generally required conformance for the walkers they sell. As of 2000, industry reported that more than 98% of the walkers being sold in the U.S. were certified as complying with the requirements. This high level of conformance was confirmed by an independent CPSC staff evaluation of the baby walker market (Leland, 2002 and CPSC, 2002).
The new stair-fall requirements appear to have been effective. Between 1991 and 2001, the baby walker injury rate fell from 8.0 to 2.2 emergency department injuries per 1000 walkers in use. Moreover, a recent study concluded that the stair-fall requirements reduced the baby walker injury rate by an estimated 63% (Rodgers and Leland, 2005). Given the substantial reduction in the risk of walker-related injury, and the high level of conformance with the revised voluntary standard, the Commission terminated the regulatory proceeding in May 2002 (CPSC, 2002).
The purpose of this article is to present a retrospective benefit-cost analysis of the voluntary standard's stair-fall requirements that went into effect almost 10 years ago. In the process, we illustrate the benefit-cost methodology used by the CPSC staff in the analysis of product-related hazards.
