Thawat Chittrakarn, Jarae Wutthisasna and Tripob Bhongsuwan

pp. 709 - 725

Abstract

Altogether 39 water samples were collected from shallow wells in Namom district, Songkhla province.
Two groups of sampling wells were recognized, i.e., a cancer related group and a no-cancer related group,
which were related with the presence or absence of evidence of oral or esophagus cancers at the home of well
owner. The pH, TDS, hardness and concentration of heavy metals and major elements (Ba, Cr, Mn, Fe, Ni,
Cu, Cd, Zn, Pb, Mg and Ca) of water samples were measured. The results showed that the pH of all water
samples ranged from 4.5 to 7.4 among which 64.1% of water samples were not complied with the rural
drinking water quality criteria B.E. 2531. Heavy metal and major element concentrations in all samples did
not comply with the quality criteria except for cadmium in 1 sample (0.0055 mg/l) and iron in 2 samples
(0.77 and 0.59 mg/l). Results of multivariate factor analysis showed that three factors were extracted from 9 variables. Factor-1 included TDS, hardness, Mg and Ca, which were interpreted as a result of granite
decomposition. Factor-2 included the concentrations of Ba and Zn, which originated from decomposed
granite in the south of Krongrang and Tungkamin sub-districts before transporting towards the north into
the Klong-Wa. Factor-3 included a single element, iron, which had no relation with any others. Results of
the t-test revealed significant differences (p<0.1) for TDS, hardness, Mg and Ca between no-cancer related
group samples and cancer related group samples. The TDS, hardness, Mg and Ca content in water samples
were certainly not related to cancer in this area but another alkali earth metal ‘radium’, a natural radioactive substance, which is a well known carcinogen, probably plays an important role in this case. Measurement and analysis of radium and radon content in this water is urgently needed to confirm the radium
content and its relation with oral and esophagus cancers in this area.

Keywords

• heavy metals
• major element
• shallow well water
• factor analysis
• cluster analysis
• cancer