Height and surfacing as risk factors for injury in falls from playground equipment: a case-control study.

OBJECTIVES: Despite the widespread promotion of safety standards no epidemiological studies have adequately evaluated their effectiveness in preventing injury in falls from playground equipment. This study evaluated the effectiveness of the height and surfacing requirements of the New Zealand standard for playgrounds and playground equipment. SETTING: Early childhood education centres and schools in two major cities in the South Island of New Zealand. METHODS: Data were collected on 300 children aged 14 years or less who had fallen from playground equipment. Of these, 110 (cases) had sustained injury and received medical attention, while 190 (controls) had not sustained injury requiring medical attention. RESULTS: Logistic regression models fitted to the data indicated that the risk of injury being sustained in a fall was increased if the equipment failed to comply with the maximum fall height (odds ratio (OR) = 3.0; 95% confidence interval (CI) 0.7 to 13.1), surfacing (OR = 2.3; 95% CI 1.0 to 5.0), or safe fall height (OR = 2.1; 95% CI 1.1 to 4.0) requirements. Falls from heights in excess of 1.5 metres increased the risk of injury 4.1 times that of falls from 1.5 metres or less and it was estimated that a 45% reduction in children attending emergency departments could be achieved if the maximum fall height was lowered to 1.5 metres. CONCLUSIONS: Although the height and surfacing requirements of the New Zealand standard are effective in preventing injury in falls from playground equipment, consideration should be given to lowering the maximum permissible fall height to 1.5 metres.

Premature centromere division: a mechanism of non-disjunction causing X chromosome aneuploidy in somatic cells of man.

Apparent acentric fragments which replaced a C-group chromosome in cultured blood lymphocytes from a woman patient were shown by autoradiography, G-banding and C-banding to be complete X chromosomes in which the centromere had divided prematurely in relation to the centromeres of other chromosomes in the same metaphase. Metaphases with multiple 'fragments' suggested that non-disjunction of the 'fragments' had occurred. This anomaly of the X chromosome was associated with increased aneuploidy of a C-group chromosome, presumed to be X. Premature centromere division of the X chromosome (PCD, X) appeared to be a mechanism of non-disjunction which caused significant monosomy and trisomy of the X chromosome in blood cells and skin fibroblasts. The frequency of cells with multiple fragments and the extent of the aneuploidy in 48 hr. blood cultures indicated that this mechanism of non-disjunction operated during mitosis both in vivo and in vitro. Premature centromere division occurred at a lower frequency in normal women donors, and was age-related, being four times more frequent in women 60 years and older than in women under 40. Associated with the higher frequency of PCD, the older women also showed evidence of increased X chromosome aneuploidy. Premature centromere division of the X chromosome is considered to be the mechanism of non-disjunction, causing the well-documented increased number of 45, -C metaphases in ageing women. Premature centromere division was rare in men, but an age effect was again suggested.