However the development of global supply chains results in an increased dependency on international trade, for both net food-exporting countries and for net food-importing countries. This may lead to a loss of export revenues for agricultural exporters when the prices of export commodities go down, as well as to threats to local producers when low priced imports arrive on the domestic markets, against which these producers are unable to compete. Conversely, when prices rise, the dependency of low income net food importing countries on the food commodities they buy on the international markets can lead to balance of payments problems against which the mechanisms currently established within the WTO have failed to protect them. The expansion of global supply chains increases the role of large transnational corporations of the agro food sector, vis-à-vis both producers and consumers. This creates a potential for abuses of market power in increasingly concentrated global food supply chains. According to Rung (1993), the expansion of trade in agricultural commodities has potential impacts on the environment and on human health and nutrition, impacts that usually receive little attention in international trade discussions, despite their close relationship to the right to adequate food. Free trade can lead to pollution and other environmental problems as companies fail to include these costs in the price of goods in trying to compete with companies operating under weaker environmental legislation in some countries (Anderson, 1991). International markets are not a level playing field as countries with surplus products may dump them on world markets at below cost. Some efficient industries may find it difficult to compete for long periods under such conditions. Further, countries whose economies are largely agricultural face unfavorable terms of trade whereby their export income is much smaller than the import payments they make for high value added imports, leading to large CADs and subsequently large foreign debt levels. And other policy that government can adopt is to increase the import tariffs, which means charging price and imposing high taxes on import items.