Overall, none of the initial hypotheses were confirmed.[citation needed] NAFTA did not inherently present a systemic threat to the North American environment, as was originally feared. NAFTA-related environmental threats instead occurred in specific areas where government environmental policy, infrastructure, or mechanisms, were unprepared for the increasing scale of production under trade liberalization.[citation needed] In some cases, environmental policy was neglected in the wake of trade liberalization; in other cases, NAFTA's measures for investment protection, such as Chapter 11, and measures against non-tariff trade barriers, threatened to discourage more vigorous environmental policy. The most serious overall increases in pollution due to NAFTA were found in the base metals sector, the Mexican petroleum sector, and the transportation equipment sector in the United States and Mexico, but not in Canada.