Human health risk assessment of atrazine in water and soil in selected municipalities in Ashanti and Brong-Ahafo Region of Ghana

Atrazine, one of the triazine herbicides, helps control the growth of weeds through inhibition of photosynthetic reactions. It is used extensively because it is economical and effective in reducing crop losses due to weed interference. It has gained much attention because of its frequent detection in surface and groundwater supplies. Even though most countries have banned the usage of atrazine due to health risk and associated environmental contamination, its is still used in Ghana. Knowledge of levels of Atrazine in the environment is essential for the protection of human health and the environment. The main objective of the study is to do a health risk assessment to show the implications of atrazine levels on human population. This is aimed at informing policy makers in pesticide management, especially Atrazine, and also to assist in protecting water resources. The study areas were maize farms in Dormaa, Sunyani and Nkoranza Districts all in the Brong Ahafo Regions as well as Offinso District in Ashanti Region, where a lot of atrazine has been used in maize production over the past ten years. Thirty-six water samples and twelve soil samples were collected in December 2011 from surface and groundwater distributed in the study areas. The herbicide was extracted from the samples using sonication and analyzed by High Performance Liquid Chromatography (HPLC). There were no detectable concentrations of Atrazine in some water bodies however others ranged from 0.004µg/L to 0.105µg/L. The highest mean value occurred at Dandwe River with mean concentration of 0.076±0.023µg/L. The streams have concentrations between 0.033µg/L and 0.111µg/L with an average of 0.071µg/L. Out of the three streams sampled. two streams showed the presence of Atrazine with averages of 0.089µg/L and 0.053µg/L. Most of the hand dug wells did not contain Atrazine above the limit of determination of 0.001µg/L. It was only in the Sunyani 1 area that the wells recorded an average of 0.004µg/L. These concentration were found to be far lower than the WHO safety level of 2µg/L for drinking water. The levels of Atrazine in parts of the unsaturated zone of the soil in Dormaa, Sunyani and Nkoranza were below detectable limits of 0.0001ng/g whiles Sunyani Farm 3 recorded an average of 125ng/g. It can be said that the study area has no problem with Atrazine contaminations in soil and water bodies. The Human Health Risk Assessment shows a Risk Quotient (RQ) of 0.01635, which shows that, the level of risk posed by Atrazine in the water within the study are is not dangerous for human consumption. There was a correlation between HPLC measurements and INAA, the results from both methods of determination were comparable. It is therefore recommended that a more extensive research is done nationwide, to screen and map Atrazine levels and particularly monitor migrations below 40cm. (au)