The number of patients rose by 51 over the last eight years, sources said.
A total of 589 people have been detected with arsenicosis, a disease caused by drinking and using of water contaminated with arsenic, in the coastal district, showing a slight rise in the number of such patients over the last eight years.
Sources at the local office of the Department of Public Health Engineering (DPHE) said there were 538 arsenicosis patients in 42 unions of all the upazilas in the district in 2011. The number of such patients was 480 in 2003.
The number of patients rose by 51 over the last eight years, they said.
Besides, 15 arsenic-affected people died in the district since 2003.
Arsenic limit set by the government is 50 micrograms per litre while that by the World Health Organization (WHO) is 10 micrograms per litre.
Of the total 59,821 tube-wells in the district, higher arsenic concentration than the normal standard was found in 25,693, said senior chemist at the local DPHE office Aynal Haque.
The arsenic contamination in shallow tube-wells is high in Dumuria, Terokhada, Rupsa, Digholia and Paikgachha upazila is high, he said.
Arsenic-affected unions include Magurgona and Rangpur in Dumuria upazila, Haridhali, Kapilmuni, Lata, Deluti, Sholadana, Laskar, Gadaipur, Radhuli and Chandkhali in Paikgachha, Amadi, Bagali and Maharajpur in Koyra, Chalna, Dacope, Tildanga and Kamarkhola in Dacope, Jalma, Bhandarcourt, Baliadanga and Amirpur of Batiaghata, Aijgati, Srifaltala, Noihati, TS Bahirdia and Ghagbhog in Rupsa, Chhagladah, Chhachiadah, Ajgora, Madhupur Terokhada and Barasa in Terokhada, Jogipool, Senhati, Digholia, Gazirhat and Barakpur in Digholia upazila.
The sources said underground water layers are gradually depleting following the lifting of water in an unplanned way with air filling the vacuum. Arsenic dissolves into water after it comes into the contact of rocks and air, they said.
DPHE Assistant Engineer Joyanta Nath Chakrabarty said the affected people are taking treatment at upazila health complexes and community clinics.