Geotoxicology of multiple sclerosis: the Henribourg, Saskatchewan, cluster focus. II. The soil.

The childhood-related, geographically-linked factor which predisposes towards (or protects against) multiple sclerosis (MS) could be one or more chemicals in the environment. Chemical study of the environment or "focus" of an MS cluster may maximize the chances of detecting such an etiological link. The soil chemistry of an MS focus (Henribourg, Saskatchewan) was compared with North American norms, and with the chemistry of soil from a nearby control area with a near-zero incidence of MS and of childhood homes of MS cases. A combination of our present results with those reported in the literature suggests that an environment predisposing to MS may have a number of the following chemical characteristics: Calcareous; with soils (but not necessarily waters) generally low in copper, iron and vanadium; with excess lead, nickel and zinc in the upper soil layer; with waters relatively high in chloride, chromium, molybdenum, nitrate plus nitrite, and zinc; but low in selenium and sulfate. One possible causal pathway to explain the apparent link between the excess rate of MS and some of the curious geochemical findings at Henribourg is presented. Many other possible explanations could equally well be advanced, and methods for testing such alternative hypotheses are proposed.