of suicide and homicide in the District of Columbia were compared to changes in rates of suicide and homicide in neighboring Maryland and Virginia counties, where no such change in firearms legislation had taken place. In the District of Columbia, subsequent to the enactment of this legislation, a 23 percent decline in firearms suicide and a 9 percent decline in non-firearms suicide were noted. Over the same period of time, in the adjoining Maryland and Virginia counties, a 12 percent increase in firearms suicide and a 2 percent decline in non-firearms suicide were observed. One weakness of all ecological studies is that it is impossible to monitor the extent to which these regulations were enforced or circumvented. However, one might have expected diffusion of unlawful firearms from neighboring counties into the District of Columbia, which would have diluted the potentially salutary impact of the legislation. The inference of a causal relationship between the change in legislation and the decline in suicide is bolstered by the greater effect on firearms vs. non-firearms suicide and the geographic specificity of this effect. Method substitution did not occur to any substantial degree, and an overall decline in the suicide rate prevailed. The impact of the Brady Act has been controversial. Although Ludwig and Cook (2000) found a significant reduction in suicide rates following enactment, their breakdown by age and their choice of duration of analysis may be problematic (Kleck and Marvell, 2000; Lott, 2000). Given the complexity of gun availability and fluctuations of these relatively infrequent events over time, a final judgement on the effectiveness of this legislation in reducing suicide is unlikely to happen soon.
The impact of firearms legislation on suicide was examined in Queensland, Australia (Cantor and Slater, 1995). The law required both current and prospective owners of long guns to obtain a license. A 28-day waiting period (“cooling off period”) was instituted prior to a new purchase, and owners were required to pass a safety test. The suicide rate by firearms declined among men in metropolitan areas and in provincial cities, but not in rural areas. This effect was most notable among individuals under the age of 30. However, method substitution occurred in all regions but the provincial cities, where overall suicide rates did decline. Two limitations of the study are the absence of a “control” community where no change in legislation had occurred and the brevity of the observation (only 1 year pre- and post-legislation).
The rate of acetaminophen (or paracetamol) self-poisoning from emergency room registries has been estimated 21.4/100,000 in one American emergency room, and as high as 70–90/100,0000 in one study based in