Artificial night light and thyroid cancer.

Area of Science:

• Environmental Health
• Epidemiology
• Oncology

Background:

• Thyroid cancer (TC) incidence has risen globally in recent decades.
• Exposure to artificial light at night (ALN) is a potential environmental risk factor for cancer.
• Investigating the relationship between ALN and TC is crucial for public health.

Purpose of the Study:

• To examine the worldwide impact of ALN exposure on thyroid cancer incidence.
• To assess ALN as an environmental pollutant in relation to TC.
• To explore potential confounding factors in the ALN-TC association.

Main Methods:

• Analysis of global satellite ALN data.
• Correlation with thyroid cancer incidence data (adjusted standardized rate - ASR).
• Inclusion of quality of cancer registries (QCR), gross domestic product (GDP), and health expenditure per person (HEP) as covariates.

Main Results:

• Initial correlation found between higher ASR and ALN exposure, particularly in high GDP/HEP countries.
• Significant differences in ASR observed across varying QCR levels.
• No significant association between ASR and ALN when controlling for GDP/HEP or QCR.

Conclusions:

• Higher GDP and health expenditure may be linked to adverse health conditions and TC risk, rather than direct ALN effects.
• Limitations include cross-sectional data and ALN as a socioeconomic proxy.
• Light pollution may indirectly relate to lifestyles conducive to cancer; higher GDP/HEP might improve TC diagnosis and reporting.