Green tobacco sickness (GTS), an occupational illness affecting tobacco harvesters, results from dermal nicotine absorption. The severity of GTS is significantly influenced by environmental factors, primarily high temperatures and rainfall. These factors increase nicotine absorption through mechanisms such as increased skin permeability due to sweating and higher blood flow to the skin surface in response to heat. The present study investigates the impact of anthropogenic climate change on the prevalence of GTS by analyzing historical and projected changes in temperature and precipitation patterns in major tobacco-producing regions. The importance of this research stems from the potential for substantial increases in GTS cases among vulnerable populations, particularly children and adolescents working in tobacco fields. This study is crucial for understanding the interplay between climate change and occupational health hazards, informing preventative measures and public health strategies to mitigate the increased risk of GTS associated with a warming climate. The increasing global prevalence of GTS, coupled with the growing evidence of climate change impacts, underscores the urgent need to quantify these effects and implement appropriate interventions. A better understanding of these relationships will contribute significantly to improving worker safety and public health initiatives within the agricultural sector, particularly in regions with significant tobacco cultivation.

Existing literature extensively documents the link between GTS and environmental conditions. Studies have shown that high temperatures and rainfall during tobacco harvesting significantly increase nicotine absorption through the skin. The mechanism involves increased perspiration, which facilitates nicotine's water-soluble nature, and increased blood flow to the skin's surface at elevated temperatures. Prior research has focused primarily on the immediate health consequences of GTS, which include nausea, vomiting, headaches, and dizziness. However, the role of climate change in exacerbating GTS has received comparatively less attention. While previous studies have explored the occupational hazards of tobacco farming, including GTS, the integration of climate change projections into risk assessments has been limited. The current understanding of GTS prevalence varies geographically, and there is often underreporting of cases due to workers not always attributing their symptoms to GTS. Studies utilizing a climate change lens to examine the impact on occupational health hazards in the agricultural sector are relatively few, creating a knowledge gap that this study aims to address.

This study analyzed recent and projected climate trends in four major tobacco-producing regions: Southern Brazil, Yunnan Province (China), Andhra Pradesh (India), and North Carolina (USA). Data on temperature and rainfall were collected from meteorological stations within these regions, focusing on the tobacco harvest periods spanning from 1970 to 2022 for recent trends. To project future climate conditions, the study utilized the Coupled Model Intercomparison Project Phase 6 (CMIP6) data and the Shared Socioeconomic Pathways (SSPs) scenarios (SSP1-2.6, SSP3-7.0, and SSP5-8.5). CMIP6 data, accessed via the KNMI Climate Explorer, provided monthly maximum temperature and precipitation projections at a 1° x 1° grid resolution. For each region, linear regression analysis was performed to determine trends in cumulative maximum daily temperatures, the occurrence of high-temperature days (defined for each region based on the initial decade of observation), cumulative rainfall (cm), and the number of rainy days. The relationship between temperature and nicotine absorption was assessed using data from nicotine transdermal patches, with the assumption that similar temperature-dependent absorption rates apply to nicotine from tobacco leaves. Statistical analyses were conducted to determine the significance of the observed and projected changes in climate parameters and their implications for nicotine absorption and GTS prevalence. The study used a proxy metric based on existing research on transdermal nicotine patches and temperature relationships to estimate potential changes in nicotine absorption based on observed and projected temperature increases in the study areas. The data is available publicly on Github and Zenodo.

The study revealed significant increases in both maximum temperatures and rainfall across all four regions since the 1970s during the tobacco harvest season. Southern Brazil showed significant increases in days above 35°C, cumulative maximum temperature, and cumulative rainfall. Similar upward trends were observed in Yunnan Province (China) for days above 30°C, cumulative maximum temperature, and cumulative rainfall. Andhra Pradesh (India) experienced significant increases in cumulative rainfall and the number of rainy days. North Carolina (USA) also showed significant increases in cumulative maximum temperature and rainfall. CMIP6 projections under SSP3-7.0 and SSP5-8.5 scenarios indicated further increases in maximum temperatures for all locations through 2100. The estimated increase in nicotine absorption using the transdermal patch proxy indicated significant increases in nicotine uptake due to both the recent observed temperature changes and the projected future increases for SSP3-7.0 and SSP5-8.5 scenarios. Under the SSP5-8.5 scenario, a 50% increase in nicotine absorption was projected by the end of the century. The analysis highlighted a significant correlation between the increase in temperature and rainfall and the predicted increase in nicotine absorption, thus increasing the risk of GTS.

This study's findings strongly suggest a critical link between climate change and increased GTS risk among tobacco workers globally. The observed and projected increases in temperature and rainfall directly influence nicotine absorption, leading to a heightened risk of GTS. The use of a transdermal patch model as a proxy for nicotine absorption from tobacco leaves provides a useful quantitative estimate, although further research is necessary to refine this method. The significant projected increases in nicotine absorption, particularly under high-emission scenarios, warrant immediate attention to implement preventative measures. The vulnerability of young workers and children, whose thinner skin and lower tolerance make them particularly susceptible to GTS, is a crucial public health concern. The study underscores the importance of considering climate change impacts when assessing occupational health risks in agriculture. Further research should focus on improving the accuracy of nicotine absorption estimates, investigating the long-term health consequences of GTS exposure, and developing targeted interventions to protect vulnerable worker populations from the increasing risk of this occupational illness.

This multi-continental study establishes a strong association between climate change and increased risk of green tobacco sickness (GTS) among tobacco workers. Observed and projected increases in temperature and rainfall significantly enhance nicotine absorption, leading to potentially substantial increases in GTS cases. The findings highlight the urgent need for preventive measures, such as improved personal protective equipment (PPE), worker education, and stricter regulations to safeguard vulnerable populations, especially children and adolescents, involved in tobacco farming. Future research should focus on refining nicotine absorption models, comprehensively evaluating the long-term health effects of GTS, and developing culturally appropriate and effective interventions to mitigate the increasing risks associated with climate change.

The study's reliance on a transdermal nicotine patch model as a proxy for nicotine absorption from tobacco leaves represents a limitation. While this approach provides a useful estimate, it does not fully capture the complexities of nicotine absorption from tobacco leaves under real-world conditions. Furthermore, the study focuses on a limited number of regions, and the generalizability of the findings to other tobacco-producing areas may require further investigation. The study also does not fully account for other factors that might influence GTS risk, such as individual worker characteristics and variations in tobacco leaf nicotine concentration.