**5. References**

Barra R.; Cisternas M.; Urrutia R.; Pozo K.; Pacheco P.; Parra O.; Focarti S. (2001). First report on chlorinated pesticide deposition in a sediment core from a small lake in central Chile, *Chemosphere,* Vol. 45, pp. 749-757.

**23** 

*1,3Namibia 2Germany* 

**Should We Be Concerned with Long-Term** 

*2Federal Institute for Geosciences and Natural Resources (BGR), Hannover,* 

In the modern world there are several sources of pesticides and other phenyl type organic compounds. Why do we use pesticides? Simply that the world's agricultural practices have commercialized to feed an overgrowing world population. Agriculture has also become a very lucrative business, where various players try to find niches to market their products. At the same time, societies have continued to become more aware about their natural environment and how to sustain it. As far back as 500 A.D., the city of Athens passed a law requiring all refuse to be disposed in a designated landfill outside the city walls (Zakrzewski, 1997); this was followed by many such laws in Europe. However direct linking of disease and health to environmental occupation was done by Dr. Percival Pott, in 1775 (quoted in Zakrzewski, 1997), who correctly linked the "chimney workers" with the unusual high rate of scrotal cancer, which he associated with exposure to soot in their work

In a city like Windhoek, pesticides may arise from the control of grasses on road pavements (Mapani, 2005); or from small scale urban agricultural gardens behind homes. However the major source of pesticides is by far from the farming industry. It is estimated that in the United States alone, close to 98% of the sprayed insecticides and 95% of the herbicides finally reach an unintended sink (destination) (Miller, 2004). The effect of this is obvious when it comes to infiltration of water into the ground that has been used in the irrigation of crops. Pesticides are one type of compounds that undergo "biomagnification" in the food chain (US EPA, 2003). This aspect is especially dangerous as it ensures that the threat from the pesticide is not decreased with time, but rather increased. The United States Environmental Protection Agency (US EPA, 2003) has classified pesticides into four categories; namely; (i) organophospates; (ii) N-methyl carbomates; (iii) triazines and (iv) chloroacetanilides. Some specific pesticide compounds have common mechanisms of toxicity, and require cumulative risk assessment over a relative long period, in order to define the potential risks. However the danger to aquatic life as described below in section 2 is well known, but the danger to human health is ill defined in comparison; with only a few

**1. Introduction** 

environment (Zakrzewski, 1997).

 **in Namibian Groundwater?** 

*1University of Namibia, Geology Department, Windhoek,* 

*3BGR Project in the Geological Survey of Namibia, Windhoek,* 

Benjamin Mapani1 and Rainer Ellmies2,3

**Health Problems Associated with Pesticides** 

