Randy Johnson 212,  Try reading Review Article
MolecularMechanisms of Cytotoxicity and Apoptosis Induced by
Inorganic Fluoride.

Anthropogenic fluoride
sources include the release of processed waters and waste
from various industrial sites, including steel, aluminum, copper
and nickel production, phosphate ore processing, phosphate
fertilizer manufacturing and use, and glass, brick, and
ceramic manufacturing [3, 4]. Phosphate ore production
and aluminum manufacture are the major industrial sources
of environmental fluoride pollution. The use of fluoride containing
pesticides and combustion of the coal and fuel also contribute to fluoride dispersion. These processes result in accumulation of fluoride compounds in the surface waters and groundwater reserves, air, soils, and in the
living organisms. Thus, the main source for humans is drinking water    

anthropogenic : of, relating to, or resulting from the influence of human beings on nature - anthropogenic sources of pollutants.