## 1 Introduction
\begin{table}
\begin{tabular}{c c c c} \hline \hline
**County** & **Region** & **[AsL \(\upmu\)g/L** & **Permissible Limit, \(\upmu\)g/L** \\ \hline Afghanistan & Ghazni & 10–500 & 10 (WHO) \\ \hline \multicolumn{4}{c}{\({}^{*}\)Argentina} & 10–1000 & 50 (WHO) \\ \hline \multicolumn{4}{c}{\({}^{*}\)Australia} & Perth & 7000 \\  & Northern New South Wales & 52–337 & 10 (WHO) \\  & Victoria (Gold mining & c1–300,000 \\ \hline Bangladesh & Noakhali & c1–4730 & 50 (WHO) \\ \hline Brazil & Mins Gerais (Southeast Brazil) & 0.4-350 (Surface water) & 10 (WHO) \\ \hline Cambodia & Prey Veng and & & \\  & Kandal-Mekong delta & Up to 9001–1610 & 10 (WHO) \\ \hline Canada & Nova Scotia & 1.5–738.8 & 10 (WHO) \\ \hline \multicolumn{4}{c}{\({}^{*}\)Chile} & 900–1040 & 50 (WHO) \\ \hline China & - & 50–4440 & 50 (WHO) \\ \hline \multicolumn{4}{c}{\({}^{*}\)China Inner Mongolia} & 1–2400 & 50 (WHO) \\ \hline \multicolumn{4}{c}{\({}^{2}\)(Shallow groundwater)} \\ \multicolumn{4}{c}{\(\#\)Croatia (Eastem)} & Osipek area & 205–240 (Deep & 10 (WHO) \\  & & groundwater) \\ \hline Finland & Southwest Finland & 17–980 & 10 (WHO) \\ \hline \multicolumn{4}{c}{\(\#\)Germany -} & 10–150 & 10 (WHO) \\ \hline \multicolumn{4}{c}{\(\#\)Ghana} & - & c1–175 & 50 (WHO) \\ \hline Greece & Fairbanks (mine tailings) & Up to 10,000 & 10 (WHO) \\ \hline \multicolumn{4}{c}{\({}^{*}\)Hungary} & Pannonian Basin & 10–176 \\  & & 0.5–240 & 10 (WHO) \\ \hline \multicolumn{4}{c}{India} & West Bengal & 10–3200 & 50 (WHO) \\  & Uttar Pradesh & & \\ \hline Italy & Volcano island and & 0.1–6940 & 10 (WHO) \\  & Phelgren Fields & & \\ \hline \multicolumn{4}{c}{\({}^{*}\)Japan} & Fukuoka Prefecture (southern region) & 1–293 & 10 (WHO) \\ \hline \multicolumn{4}{c}{\(\#\)Lao PDR} & Laos & 277.8 & 50 (WHO) \\ \hline Mexico & Lagunera & 8–620 & 25 \\ \hline Nepal & Rupandehi & Up to 2620 & 50 \\ \hline \multicolumn{4}{c}{\(\#\)New Zealand} & Taupe Volcanic zone & 21 & 10 (WHO) \\ \hline Pakistan & Muzzafargahr & & \\  & (southwestern Punjab) & Up to 906 & 50 \\ \hline \multicolumn{4}{c}{\({}^{*}\)Peru} & 500 & 50 (WHO) \\ \hline \multicolumn{4}{c}{\({}^{*}\)Romania} & 10–176 & 10 (WHO) \\ \hline \multicolumn{4}{c}{\(\#\)Slovakia} & Banska Bystricta and Nitra & 37–39 & 10 (WHO) \\ \hline \multicolumn{4}{c}{\(\#\)Spain} & - & c1–100 & 10 (WHO) \\ \hline Taiwan & - & 10–1820 & 10 (WHO) \\ \hline Thailand & Ron Philbun & 1–\(\gamma\)5000 & 10 (WHO) \\ \hline \multicolumn{4}{c}{\(\#\)UK} & Southwest England & \multicolumn{1}{c}{\(<\)1–80} & 10 (WHO) \\ \hline USA & Tulare Lake & Up to 2600 & 10 (USEPA) \\ \hline \multicolumn{4}{c}{\(\#\)River Delta} \\ \multicolumn{4}{c}{Vietnam} & \multicolumn{1}{c}{(North Vietnam)} \\ \multicolumn{4}{c}{Mekong Delta} & \multicolumn{1}{c}{\(<\)1–3050} & 10 (WHO) \\ \multicolumn{4}{c}{(South Vietnam)} \\ \hline Adapted and modified from [3], \({}^{*}\)[15] and \(\#\)[25]. & \multicolumn{1}{c}{} \\ \end{tabular}
\end{table} 
Table 1: Global variation of arsenic concentrations in groundwater. standard for arsenic in drinking water and this may spread to other countries [15]. Due to the greater risk that arsenic contamination of groundwater poses to the Bangladesh people, it is useful to take a closer look at the widespread nature of the problem in this country.