This article aims to alert the medical community and public health authorities to accumulating evidence on health benefits from sun exposure, which suggests that insufficient sun exposure is a significant public health problem. Studies in the past decade indicate that insufficient sun exposure may be responsible for 340,000 deaths in the United States and 480,000 deaths in Europe per year, and an increased incidence of breast cancer, colorectal cancer, hypertension, cardiovascular disease, metabolic syndrome, multiple sclerosis, Alzheimer’s disease, autism, asthma, type 1 diabetes and myopia. Vitamin D has long been considered the principal mediator of beneficial effects of sun exposure. However, oral vitamin D supplementation has not been convincingly shown to prevent the above conditions; thus, serum 25(OH)D as an indicator of vitamin D status may be a proxy for and not a mediator of beneficial effects of sun exposure. New candidate mechanisms include the release of nitric oxide from the skin and direct effects of ultraviolet radiation (UVR) on peripheral blood cells. Collectively, this evidence indicates it would be wise for people living outside the tropics to ensure they expose their skin sufficiently to the sun. To minimize the harms of excessive sun exposure, great care must be taken to avoid sunburn, and sun exposure during high ambient UVR seasons should be obtained incrementally at not more than 5–30 min a day (depending on skin type and UV index), in season-appropriate clothing and with eyes closed or protected by sunglasses that filter UVR.

Little is known about the risk of progression of lentigo maligna to lentigo maligna melanoma. We determine the annual risk of progression of lentigo maligna to lentigo maligna melanoma by analysing a prospective population-based survey of recently diagnosed anterior (visible in a mirror) head and neck lentigo malignas and lentigo maligna melanomas. Six hundred eighty-two consecutive patients aged 18–80 years with non-recurrent lentigo maligna or lentigo maligna melanoma, diagnosed between 1 July 2015 and 20 April 2016, were identified from pathology notifications to the New South Wales Cancer Registry (Australia) and sent survey questionnaires soon after diagnosis (median 4.6 months interquartile range: 3.8–5.7). Details of the time the lesion was present and when changes to it were noticed before diagnostic biopsy were ascertained by surveying the patients, of whom 53.5% agreed to participate. There was little difference between the proportions of lentigo maligna melanoma and lentigo maligna in the consenting and non-consenting patients (P = 0.56). Two hundred twenty-eight lentigo maligna (median age 67 years, range: 38–80) and 33 lentigo maligna melanoma (70 years, 43–80) were surveyed. There was no difference between the time lentigo maligna melanoma was present on the skin (median 18 months, range: 0–690) and the time lentigo maligna was (18 months, 0–665) (P = 0.972). The estimated risk of progression of lentigo maligna to lentigo maligna melanoma was 3.5% per year (95% confidence interval: 2.5–5.0). This equates to an average time for lentigo maligna to progress to lentigo maligna melanoma of 28.3 years (95% confidence interval: 20.0–40.5) in this population. Although our data suggests that the annual progression rate of lentigo maligna is more than 25 times greater than previously suggested, the rate is still low.

In recent decades, the possibility that use of mobile communicating devices, particularly wireless (mobile and cordless) phones, may increase brain tumour risk, has been a concern, particularly given the considerable increase in their use by young people. MOBI-Kids, a 14-country (Australia, Austria, Canada, France, Germany, Greece, India, Israel, Italy, Japan, Korea, the Netherlands, New Zealand, Spain) case-control study, was conducted to evaluate whether wireless phone use (and particularly resulting exposure to radiofrequency (RF) and extremely low frequency (ELF) electromagnetic fields (EMF)) increases risk of brain tumours in young people. Between 2010 and 2015, the study recruited 899 people with brain tumours aged 10 to 24 years old and 1,910 controls (operated for appendicitis) matched to the cases on date of diagnosis, study region and age. Participation rates were 72% for cases and 54% for controls. The mean ages of cases and controls were 16.5 and 16.6 years, respectively; 57% were males. The vast majority of study participants were wireless phones users, even in the youngest age group, and the study included substantial numbers of long-term (over 10 years) users: 22% overall, 51% in the 20-24-year-olds. Most tumours were of the neuroepithelial type (NBT; n = 671), mainly glioma. The odds ratios (OR) of NBT appeared to decrease with increasing time since start of use of wireless phones, cumulative number of calls and cumulative call time, particularly in the 15-19 years old age group. A decreasing trend in ORs was also observed with increasing estimated cumulative RF specific energy and ELF induced current density at the location of the tumour. Further analyses suggest that the large number of ORs below 1 in this study is unlikely to represent an unknown causal preventive effect of mobile phone exposure: they can be at least partially explained by differential recall by proxies and prodromal symptoms affecting phone use before diagnosis of the cases. We cannot rule out, however, residual confounding from sources we did not measure. Overall, our study provides no evidence of a causal association between wireless phone use and brain tumours in young people. However, the sources of bias summarised above prevent us from ruling out a small increased risk.

When investigating the association between brain tumors and use of mobile telephones, accurate data on tumor position are essential, due to the highly localized absorption of energy in the human brain from the radio-frequency fields emitted. We used a point process model to investigate this association using information that included tumor localization data from the INTERPHONE Study (Australia, Canada, Denmark, Finland, France, Germany, Israel, Italy, Japan, New Zealand, Norway, Sweden, and the United Kingdom). Our main analysis included 792 regular mobile phone users diagnosed with a glioma between 2000 and 2004. Similar to earlier results, we found a statistically significant association between the intracranial distribution of gliomas and the self-reported location of the phone. When we accounted for the preferred side of the head not being exclusively used for all mobile phone calls, the results were similar. The association was independent of the cumulative call time and cumulative number of calls. However, our model used reported side of mobile phone use, which is potentially influenced by recall bias. The point process method provides an alternative to previously used epidemiologic research designs when one is including localization in the investigation of brain tumors and mobile phone use.

Childhood brain tumors (CBT) are the second most common childhood cancers, yet their etiology is largely unknown. We investigated whether maternal gestational intake of folate and vitamins B6 and B12 was associated with CBT risk in a nationwide case-control study conducted 2005–2010. Case children 0–14 years were recruited from all 10 Australian pediatric oncology centers. Control children were recruited by national random digit dialing, frequency matched to cases on age, sex, and state of residence. Dietary intake was ascertained using food frequency questionnaires and adjusted for total energy intake. Data from 293 case and 726 control mothers were analyzed using unconditional logistic regression. The odds ratio (OR) for the highest versus lowest tertile of folate intake was 0.70 [95% confidence interval (CI): 0.48, 1.02]. The ORs appeared lower in mothers who drank alcohol during pregnancy (OR = 0.45, 95% CI: 0.22, 0.93), mothers who took folic acid (OR = 0.67, 95% CI: 0.42, 1.06) or B6/B12 supplements (OR = 0.51, 95% CI: 0.25, 1.06) and in children younger than 5 years (OR = 0.50, 95% CI: 0.27, 0.93). These findings are consistent with folate's crucial role in maintenance of genomic integrity and DNA methylation. Dietary intake of B6 and B12 was not associated with risk of CBT.

Acute lymphoblastic leukemia (ALL) and childhood brain tumors (CBT) are 2 of the most common forms of childhood cancer, but little is known of their etiology. In 2 nationwide case-control studies we investigated whether breastfeeding, age of food introduction, or early diet are associated with the risk of these cancers. Cases aged 0–14 years were identified from Australian pediatric oncology units between 2003 and 2007 (ALL) and 2005 and 2010 (CBT) and population-based controls through nationwide random-digit dialing. Mothers completed questionnaires giving details of infant feeding up to the age of 2 yr. Data from 322 ALL cases, 679 ALL controls, 299 CBT cases, and 733 CBT controls were analysed using unconditional logistic regression. Breastfeeding was associated with a reduced risk of ALL [odds ratio (OR) = 0.52, 95% confidence interval (CI): 0.32, 0.84), regardless of duration. Introduction of artificial formula within 14 days of birth was positively associated with ALL (OR = 1.57, 95% CI: 1.03, 2.37), as was exclusive formula feeding to 6 mo (OR = 1.81, 95% CI: 1.07, 3.05). No associations were seen between breastfeeding or formula use and risk of CBT. Our results suggest that breastfeeding and delayed introduction of artificial formula may reduce the risk of ALL but not CBT.