It has been hypothesized that during the last several decades human sperm count has declined because of prenatal exposure to environmental chemicals. We examined the relation between semen quality and birth year among...It has been hypothesized that during the last several decades human sperm count has declined because of prenatal exposure to environmental chemicals. We examined the relation between semen quality and birth year among 8608 men born from 1922 to 1971 and who from 1968 to 1992 consulted 4 Danish medical centers because of barren marriage. Data were obtained from medical records and by a postal questionnaire to a subset of the population. The sperm concentration was significantly declining with increasing year of birth in 2 of the 4 centers, but this association disappeared when confounders were adjusted for. Within the subset of men born during 1955~1970 comprising 36% of the entire population we revealed a decrease of the average sperm concentration by 1.6 million /ml (95% CI:0.7~2.5) per one advancing year of birth.This finding was consistent across all the 4 centers and robust to adjustment for effects of calendar period, season and duration of sexual abstinence. Effects of age were accounted for by restriction of the sample to men between 20 and 45 years. The findings are compatible with environmental impact in the prenatal period after 1955 but are far from unequivocal evidence that the sperm count in the general male Danish population has changed during the past decades.展开更多
Taking the tobacco-growing area of Shashi Town,Liuyang City as the object,the number of registered,newly added and resigned tobacco farmers in each year,average age,number and proportion of tobacco farmers of differen...Taking the tobacco-growing area of Shashi Town,Liuyang City as the object,the number of registered,newly added and resigned tobacco farmers in each year,average age,number and proportion of tobacco farmers of different ages,number and proportion of tobacco farmers born in different eras,as well as planting scale and planting history of flue-cured tobacco in the last 10 years were analyzed statistically.The results showed that the number of tobacco farmers in Shashi Town showed a rapid decline trend from 2012 to 2018,while the average age continuously increased,and the average planting scale rose in a wave like way.From 2019 to 2021,the decline rate of the number of tobacco farmers slowed down,and the average planting scale continuously increased,while the aging of tobacco farmers accelerated.Meantime,the birth years of tobacco farmers were further concentrated in the 1960s,and they were mainly at the age of 50-59.The tobacco industry in Shashi Town of Liuyang City is facing the crisis of aging tobacco farmers and no successor of flue-cured tobacco planting,and it is predicted that the next 5-10 years will continue the change trend from 2019 to 2021.展开更多
文摘It has been hypothesized that during the last several decades human sperm count has declined because of prenatal exposure to environmental chemicals. We examined the relation between semen quality and birth year among 8608 men born from 1922 to 1971 and who from 1968 to 1992 consulted 4 Danish medical centers because of barren marriage. Data were obtained from medical records and by a postal questionnaire to a subset of the population. The sperm concentration was significantly declining with increasing year of birth in 2 of the 4 centers, but this association disappeared when confounders were adjusted for. Within the subset of men born during 1955~1970 comprising 36% of the entire population we revealed a decrease of the average sperm concentration by 1.6 million /ml (95% CI:0.7~2.5) per one advancing year of birth.This finding was consistent across all the 4 centers and robust to adjustment for effects of calendar period, season and duration of sexual abstinence. Effects of age were accounted for by restriction of the sample to men between 20 and 45 years. The findings are compatible with environmental impact in the prenatal period after 1955 but are far from unequivocal evidence that the sperm count in the general male Danish population has changed during the past decades.
基金Supported by Science and Technology Project of Changsha Tobacco Company(20-22B02).
文摘Taking the tobacco-growing area of Shashi Town,Liuyang City as the object,the number of registered,newly added and resigned tobacco farmers in each year,average age,number and proportion of tobacco farmers of different ages,number and proportion of tobacco farmers born in different eras,as well as planting scale and planting history of flue-cured tobacco in the last 10 years were analyzed statistically.The results showed that the number of tobacco farmers in Shashi Town showed a rapid decline trend from 2012 to 2018,while the average age continuously increased,and the average planting scale rose in a wave like way.From 2019 to 2021,the decline rate of the number of tobacco farmers slowed down,and the average planting scale continuously increased,while the aging of tobacco farmers accelerated.Meantime,the birth years of tobacco farmers were further concentrated in the 1960s,and they were mainly at the age of 50-59.The tobacco industry in Shashi Town of Liuyang City is facing the crisis of aging tobacco farmers and no successor of flue-cured tobacco planting,and it is predicted that the next 5-10 years will continue the change trend from 2019 to 2021.
文摘目的:先天性出生缺陷是中国5岁以下儿童疾病负担的主要来源。本研究旨在通过分析1990年至2019年间中国5岁以下儿童不同先天性出生缺陷的疾病负担变化趋势,为加强出生缺陷综合防治提供科学依据。方法:基于2019年全球疾病负担研究(global burden disease,GBD)数据库,选取1990年至2019年中国5岁以下儿童先天性出生缺陷的发病率、死亡率及伤残调整寿命年(disability-adjusted life year,DALYs)率作为评价指标,采用Joinpoint回归模型分析1990年至2019年30年间,不同类型先天性出生缺陷疾病负担的变化趋势,并按性别比较5岁以下儿童先天性出生缺陷疾病负担的差异。结果:与1990年相比,2019年中国5岁以下儿童先天性心脏异常(1931.91/10万)、先天性消化系统畸形(364.63/10万)、神经管畸形(277.20/10万)、先天性肌肉骨骼和肢体异常(133.33/10万)及唐氏综合征(128.22/10万)的DALYs率分别降低了70.78%、71.61%、86.21%、36.84%及73.65%。1990年至2019年,中国5岁以下儿童不同先天性出生缺陷的死亡率和DALYs率总体上均呈下降趋势,但先天性消化系统畸形和唐氏综合征的发病率分别在2005年和2001年后开始呈现逐渐上升趋势;除先天性肌肉骨骼和肢体异常外,其余几类出生缺陷的发病率均是男童高于女童。结论:1990年至2019年中国5岁以下儿童先天性出生缺陷的疾病负担大幅度下降,但先天性心脏异常疾病负担仍很严重且有些出生缺陷的发病率有上升趋势,需继续加强儿童出生缺陷的防治并根据其性别特征提出针对性措施。
