Smoking was established as a cause of lung cancer in the late 1950s. It then took another 50 years to establish that colorectal cancer was also a smoking-related cancer. However, as of 2018, a causal relationship between smoking and breast cancer had not yet been established. It may seem strange that it is taking so long to prove that smoking is a cause of all three of the most common cancers globally. Breast and lung cancer each account for 2.09 million cases annually and colorectal cancer for 1.8 million.
Tricia L Larose, Arnulf Langhammer and Mattias Johansson, for the Lung Cancer Cohort Consortium (LC3)
Lung cancer is one of the most common cancers worldwide, accounting for 2.09 million cases and 1.76 million deaths in 2018. Two of the most prolific cancer epidemiologists of our time — Sir Richard Doll and Sir Bradford Hill — identified smoking as the biggest cause of lung cancer in their seminal report, “Smoking and Carcinoma of the Lung”, published in the British Medical Journal in 1950. Nearly 70 years later, smoking remains the predominant risk factor for lung cancer, as well as for 15 additional cancers and other non-communicable diseases.
Jennyfer Wolf, Richard Johnston, Matthew C Freeman and Annette Prüss-Ustün
Handwashing with soap after faecal contact is key to preventing disease and death from enteric infectious diseases. Our study, recently published in the IJE, is the first to provide global, regional and country estimates of handwashing with soap after potential contact with human faeces, based on representative data on access to handwashing facilities collected for monitoring of the Sustainable Development Goals (SDGs). Our results show that handwashing with soap after using the toilet or other potential contact with human faeces is poorly practised worldwide and that even the necessary equipment – handwashing facilities with soap and water – are inaccessible to billions of people.
Alba Ripoll Gallardo, Barbara Pacelli and Elias Allara
Population growth and urbanisation of seismic areas are leading to a constant increase in the health-related and economic toll of earthquakes. In 2014 alone, 324 natural disasters were reported worldwide, resulting in 141 million casualties and nearly $100 billion in damage. Geophysical disasters, including earthquakes, accounted for about 10% of these events.
Although the impact of earthquakes in the response phase – that is, immediately or shortly after the main seismic event – has been well studied, we have little knowledge of the effects of earthquakes in the medium and long term. This uncertainty may cause inefficient planning of post-earthquake epidemiological surveillance, resulting in potential underestimation of public health needs.
Cerebral palsy is the most common physical disability among children, with about two per 1000 live-born infants being diagnosed with the disorder. In most children with cerebral palsy, the disability is caused by damage to the immature brain during pregnancy or birth that results in problems with movement.
Denmark and Norway have low income inequality and free access to education and offer high-quality antenatal care to pregnant women free of charge. Nevertheless, in our study recently published in the International Journal of Epidemiology, we found that the risk of having a child with cerebral palsy in these two countries varies by the parents’ educational level, and this educational gradient has been surprisingly stable over time.
The Obstetrics and Periodontal Therapy (OPT) Study was an NIH-funded randomised controlled trial designed to evaluate whether periodontal treatment in pregnant women had any effect on preterm birth; its findings were published in 2006. The investigators randomly assigned about 800 women who had been pregnant for less than 16 weeks, and had periodontal disease, to one of two groups. One group received periodontal treatment during pregnancy, whereas the other group received treatment after pregnancy.
Although the study found that treatment controlled periodontal infection and reduced the microorganism load, there was no difference in preterm birth rates between the two groups. The investigators concluded that treating periodontal disease during pregnancy did not affect the risk of preterm birth. However, they also found that there were more stillbirths in the group that received treatment after pregnancy, suggesting that periodontal treatment may improve survival of fetuses. The potential bias resulting from the intervention affecting both the outcome (in this case, preterm birth) and survival (in this case, stillbirth) was acknowledged as a limitation.
Childhood overweight and obesity are a global public health problem. In high-income countries, obesity follows socioeconomic patterns, in that people with a lower socioeconomic position are more likely to be overweight or obese than those with a higher socioeconomic position. Poor diet is a key risk factor for excess weight gain. It is also a risk factor that we can do something about.
Findings from a community-based 5-year cluster randomised trial
Masamitsu Kamada, I-Min Lee and Ichiro Kawachi
Despite the well-known health benefits of physical activity, physical inactivity remains highly prevalent globally. Effective population strategies to promote physical activity are needed to reduce the global burden of non-communicable diseases stemming from physical inactivity. But the question is: how do we effectively promote physical activity at the population level, such as in entire communities?
Reducing child mortality remains one of the key objectives of the Sustainable Development Goals. Remarkable progress has been made over the past 25 years, with the global number of deaths of children aged under 5 falling from 13 million in 1990 to six million in 2015. Yet little is known about the relative contributions of specific public health interventions and general improvements in socioeconomic status and educational attainment over the same period.
Elias Nosrati, Michael Ash, Michael Marmot, Martin McKee and Lawrence P King
Health inequalities are on the rise in the United States: the gap in life expectancy between those at the top and the bottom of the income spectrum has increased rapidly since the dawn of the century, to the point where the lives of the poor are cut short by up to a decade and a half compared with those of the wealthy. Moreover, while the rich tend to live longer everywhere, life expectancy among the poor varies significantly by geographical region.
In our article recently published in the IJE, we show that these patterns of health are the product of powerful political and economic forces. Over the past few decades, neoliberal politics, the decline of unions and economic globalisation have resulted in rapid industrial restructuring and economic dislocation in the US. Organised labour has been eroded in the industrial heartland, and manufacturing operations have been shifted to the non-unionised south and to foreign countries.