Introduction

Work-related leukemia in 2019 was estimated to represent a disease burden worldwide of 1.4 years of life adjusted for disability, higher in men than in women. Moreover, evidence shows an increase in work-related leukemia in the Andean region of Latin America [1].

According to administrative records provided by the General Workers' Risk Insurance, seven cases of work-related leukemia have been recognized in the Ecuador between 2019 and 2020. Only 2 of the 24 provinces that make up the national territory registered cases. The qualified cases fell among workers in agriculture, manufacturing industries, and health services.

The available information indicates an under-reporting and under-recognition of work-related leukemias worldwide and particularly in Ecuador [2,3]. Unfortunately, the actual number of cases may differ from official records. In many cases, this situation may be due to the lack of knowledge of occupational exposure.

Although it cannot be conclusively confirmed that outcomes are due to the work enviorment, these data could be used to estimate the burden represented by leukemias for the population in working ages, as well as for those territories most affected.

The purpose of this brief report is to present the morbidity and mortality rates for leukemias in working ages in the Ecuadorian provinces with data from official records in Ecuador. In this way, we could counteract the existing gap on this issue and provide guidance on epidemiological surveillance for certain economic activities in some provinces of the country.

Methods

For the calculation of morbidity and mortality rates (age-standardized) and confidence intervals (95% CI), administrative records of hospital discharges and deaths with codes C91 (lymphoid leukemia), C92 (myeloid leukemia), and C93 (monocytic leukemia) were used for the most recent year available in the country (2021). The age range between 15 and 69 years was considered as the working age population. The information was obtained from the website of the National Institute of Statistics and Census (https://www.ecuadorencifras.gob.ec).

Results

For 2021, 1745 patients were treated for leukemias: 60.1% for C91, 39.5% for C92, and 0.3% (6 patients) for C93. Figure 1 represents 3.4% of the 50 595 cases registered for neoplasms. Regarding mortality, 4.3% (265 deaths) of the total deaths from neoplasms (6184 deaths), 57.7% corresponded for C91, 41.9% for C92, and 0.4% (1 death) for C93.

Figure 1

Distribution of morbidity and mortality rates for leukemias by provinces in the Republic of Ecuador, 2021.

Source: Prepared by the authors of this study.

Full size

Regarding the province of residence of the person affected by leukemia, the highest percentage of treated and deceased patients were concentrated in 2 out of the 24 provinces of the country: Pichincha (21.6% and 22.3%, respectively) and Guayas (20.9% and 23.8%, respectively). However, after standardizing rates by considering the unequal age distribution of the studied population among provinces, eight provinces with the highest morbidity and mortality rates for leukemias for the population in working ages were identified in Figure 1.

In particular, the provinces of Azuay and Tungurahua stand out with the highest morbidity and mortality rates. Azuay province had 29.2 treated patients (95% CI: 29.1 to 29.3) and mortality was 3.92 (95% CI: 3.89 to 3.96) per 100,000 inhabitants. Although with mortality rates lower than 3.5, the provinces of Loja and Morona Santiago ranked second and third in the morbidity ranking. Similarly, the province of Imbabura ranked sixth in morbidity. On the other hand, the province of Pastaza ranked first in mortality with 6.21 deaths per 100 000 inhabitants (95% CI: 6.17-6.25), although with very low morbidity rates. Likewise, the provinces of Santo Domingo de los Tsáchilas and Cotopaxi followed in the third and fourth positions of the mortality ranking.

Discussion

Leukemias cause significant economic and social costs due to prolonged work disability during treatment and years of life lost due to premature death in working ages [3]. For most workers, quality information on previous exposures is not always available, partly because occupational safety concern in our country is relatively recent. Secondly, it is likely that not enough attention has been paid to occupational variables, neglecting its impact.

Some studies have observed that exposure to pesticides and herbicides could be related to the risk of developing leukemia [4,5]. In our results, provinces Azuay, Cotopaxi, Imbabura, Santo Domingo de los Tsáchilas, and Tungurahua have been observed with high morbidity and mortality rates, characterized by agricultural activity. Recently, the proliferation of greenhouses in crops is increasing in the country. Another important aspect of agrochemical use has been the association between childhood leukemia and parental exposure.

The oil industry is another pillar of the Ecuadorian economy and is mainly concentrated in the provinces of the Amazon region. We are surprised by the absence of qualified cases among affiliated workers and the low morbidity and mortality rates for provinces with a higher presence of this economic activity, with the exception of Morona Santiago, Pastaza, and Zamora Chinchipe. Other studies conducted in the provinces of Napo, Orellana, and Sucumbíos have pointed out excess mortality from leukemia in communities adjacent to oil fields [6,7].

Finally, mining has increased in the country in recent years, although illegally in the provinces of Azuay, Loja, and Imbabura. Our results show that these provinces have high morbidity and mortality rates compared to other provinces. There are suspicions about the relationship between the development of leukemias among mining workers and exposure to minerals containing carcinogenic agents and radon gas [8].

The Republic of Ecuador is located on the equator line and crossed from north to south by the Andes Mountain rangeand due to its latitude, the total amount of solar radiation is higher [9]. There are several cities located on average more than 2500 meters above sea level which are in provinces of the country in the highest rankings of morbidity and mortality, such as Azuay, Loja, Imbabura, and Tungurahua.

Conclusion

The marked differences in morbidity and mortality of leukemias in the different provinces and regions of the country suggest triggers linked to demographics and economic activities. Our work is a first approach to this problem in Ecuador. Spatial Bayesian analysis of leukemias mortality would allow us to guide future research studies that achive more refined explanations. Ecuador, given its population distribution, has the ideal conditions for this type of study.