Groundwater fluoride in Sri Lanka: opportunities to mitigate the risk at maximum contaminant level.

INTRODUCTION

High groundwater fluoride (F) is one of the major environmental hazards in the dry zone of Sri Lanka. The prolonged exposure to F at maximum contaminant levels can give rise to lifelong debility and disability among its inhabitants.

OBJECTIVES

This study investigated the F contamination in groundwater resources in Sri Lanka above recommended Maximum Contaminant Levels (MCL) and possibilities to mitigate the health risk.

METHODS

Groundwater samples (6107) were randomly collected from different geographic areas of the country, and categorised as hazardous, if it exceeded the maximum contaminant level of 4 mg/L (the level at which bone health is compromised). The minimum distances from a hazardous to a relatively safe F groundwater source (below 1.0 mg/L and 1.5 mg/L) were determined using geospatial analysis.

Results

Only 2.3% (142) of the total sample was found to be hazardous to skeletal health. Optimal F sources were identified in close proximity to highly contaminated sources (>4.0 mg/L), some even within a walking distance of 500 metres.

CONCLUSIONS

The identification and elimination of maximally contaminated sources, possibly by dilution with widely available low F sources in close proximity, would be a more feasible and cost effective approach to ensure long term public health benefits.