Artificial Light at Night and Cancer: Global Study

Area of Science:

• Environmental Health
• Oncology
• Epidemiology

Background:

• Artificial light at night (ALAN) is a growing environmental concern.
• Previous research suggests a link between ALAN and increased risk of specific cancers, such as breast and colorectal cancer.
• The detailed association of ALAN as an environmental risk factor with human cancers remains understudied.

Purpose of the Study:

• To investigate the association between ALAN and all forms of cancer across 158 countries.
• To quantify the relationship between light pollution indicators and age-standardized cancer rates.
• To explore variations in this association based on country income levels.

Main Methods:

• An ecological study utilizing global data from January to June 2015.
• Exposure variables: Protected Area Light Pollution Indicator (PALI) and Protected Area Human Influence Indicator (PAHI).
• Outcome measure: Age-standardized rates (ASR) of cancers. Statistical analyses included Pearson's correlations and linear regression, adjusted for confounders like population, electricity consumption, air pollution, and forest cover.

Main Results:

• Both PALI and PAHI showed a positive association with ASR of all cancers and the four most common cancers (p < 0.05).
• These correlations remained significant for PAHI with all cancers, lung, breast, and colorectal cancer after adjustments.
• The variation in cancer rates explained by PALI and PAHI ranged from 3.3% to 35.5%, with associations varying by country income level.

Conclusions:

• Artificial light at night is significantly correlated with all forms of cancer, as well as lung, breast, colorectal, and prostate cancers individually.
• Findings highlight the need for immediate measures to limit ALAN in urban areas and homes worldwide.
• ALAN represents a modifiable environmental risk factor for cancer that warrants further investigation and public health intervention.