Abstract

MORA ALVARADO, Darner A; CHAMIZO GARCIA, Horacio  and  MATA SOLANO, Ana. Cáncer gástrico en Costa Rica: ¿existe o no relación con la cloración del agua para consumo humano?. Rev. costarric. salud pública [online]. 2007, vol.16, n.30, pp.62-73. ISSN 1409-1429.

Gastric cancer (GC) is the leading cause of cancer-related mortality in Costa Rican males. After breast cancer, it is the second highest cause of cancer mortality in women in Costa Rica. From a histological point-of-view, GC is divided into two types: the first is the "diffuse" type and it has been related etiologically to genetic factors; the second type is the "intestinal" type and it has been linked to such environmental carcinogenic factors as: toxic chemical substances, geographic altitude and age. Along these lines, some researchers have studied possible relationships bet-tween epidemiological and ecological factors such as, for example, physico-chemical traits of water for human consumption (ACH), soils, pesticide use as well as carcinogen intake in milk such as Pteridium aquilinum (the so-called male fern). Regarding ACH, since 1974, water chlorination has been causally linked to formation of byproducts of disinfection like chloroform and bromoform, so-called trihalomethanes, which have a propensity for causing a higher incidence of GC in the population. These facts, along with media hype, have provoked uncertainty and doubts regarding the safety of chlorinated water among the public. With this background in mind, an exploratory-ecological epidemiological study was carried out with the explicit purpose of analyzing if there is or if there isn´t a statistically significant link between the incidence of GC and the consumption of chlorinated water in Costa Rica. The analysis used the GC-mortality results in 458 districts during the years 1999 to 2002 and the data obtained from the National Water Laboratory on the type of water (chlorinated or not), the number of years of disinfection and the source of the water (underground, surface or mixed). For the statistical analysis, a Standardized Mortality Index (IME) and the Pearson correlation coefficient were used. Results showed no relationship between incidence of GC and the chloration of water for human consumption (ACH), even after taking into account the number of years of chloration and also the type of water source used (underground or superficial). Lastly, it is recommended that the Costa Rican Institute of Waters and Sewer Systems (A y A) as the leading supplier of drinking water, carry out an educational campaign with the purpose of reducing the lack of user confidence in the consumption of chlorinated ACH. Besides, A y A must promote the study of the relationship of ACH with other types of cancer such as bladder and colorectal cancer.

Keywords : Stomach cancer; gastric cancer; exposure; chlorination; incidence; disinfection; Costa Rica.

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