Occupational and environmental cancer incidence and mortality in China.

BACKGROUND: Most cancers are due to environmental, occupational or other non-genetic factors and are potentially preventable. AIMS: To provide an evidence-based assessment of the burden of occupational and environmental-related cancers in China in 2005. METHODS: The population attributable fraction (PAF) was calculated based on the assumption of no occupational agent exposure. Relative risk estimates for specific cancers of interest and prevalence of exposure were mainly derived from large-scale studies. Data on cancer incidence and mortality was obtained from the Third National Death Cause Survey and cancer registries in China. RESULTS: We estimated that a total of 48,511 deaths of cancer were attributable to occupational agents in China in 2005, with 34,975 among men (3.1% of all cancer deaths) and 13,536 among women (2.1%). A total of 59,410 incident cases of cancer were attributable to occupational agents in China in 2005, with 42,724 among men (2.8% of all cancer incident cases) and 16,686 among women (1.6%). The highest PAF was observed for mesothelioma with asbestos, followed by leukaemia, bladder and lung cancers. Indoor radon was responsible for 0.2% of lung cancer-related deaths among men and women. CONCLUSIONS: Occupational agents represent an important cause of cancer, but indoor radon plays a relatively limited role in cancer causes in China. Our report provides strong evidence of the need for policy makers to develop strategies to reduce the risk of occupational cancers.

Movement characteristics of boar sperm obtained from the oviduct or hyperactivated in vitro.

The objectives of this study were to describe hyperactivated motility in boar sperm and to determine the incidence of hyperactivation among boar sperm flushed from the oviduct. Oviducts were surgically removed from 13 gilts 32 hours after mating them to fertile boars. The majority of the sperm flushed from the oviducts was immotile, weakly motile, or stuck to mucus or cellular debris. The mucus could not be penetrated by the sperm. The remaining 3% to 19% of the flushed sperm was free-swimming. Only five hyperactivated sperm were recovered, all from the ampulla of the oviduct. The remainder of the free-swimming sperm travelled in linear trajectories and possessed significantly higher flagellar curvature ratios (the flagella were less bent) than boar sperm measured in diluted semen. Hyperactivated motility was induced in washed ejaculated boar sperm, using a 1-minute pulse of 4 mumol/L calcium ionophore A23187. The ionophore-treated sperm had significantly lower straight-line velocities, linearities, and flagellar curvature ratios than controls, as would be expected for hyperactivated sperm. They were vigorous and swam in circles. It was concluded that, although few hyperactivated boar sperm could be recovered from the oviduct, boar sperm are capable of undergoing hyperactivation.