Environmental Engineering Reference
In-Depth Information
maize. For maize, the negotiated 15-year transition to free trade was eliminated (Nadal,
2000). From NAFTA's inception in 1994 the TRQ was not enforced. Beginning in 1996, US
exports to Mexico increased dramatically, from a pre-NAFTA average (1990-93) of 1.6
million tons to 6.3 million tons. With annual
uctuations, US exports have averaged around
5 million tons since 1996, a 323 percent increase from the pre-NAFTA period (FATUS,
2003).
In Mexico, the
fl
cant drop in producer prices. Real
prices fell by 25 percent in the years following NAFTA. By 2002 they were 47 percent
below their pre-NAFTA levels (SIACON, 2003).
fl
ood of imports produced a signi
fi
US environmental impacts
The changes since the adoption of NAFTA have resulted in an increase in exports to
Mexico from 0.8 percent to 2.1 percent of total US corn production. Thus the growth in
trade amounts to an additional 1.3 percent of the US corn crop, and can be credited with
1.3 percent of the impacts of corn production, both positive and negative, in the USA.
US corn production remained fairly stable during this period, so rising exports to Mexico
did not result in an increase in corn production. Rather, rising Mexican demand prevented
a possible decline due to reduced demand in other export markets.
It is important to use a broad approach in assessing NAFTA's impact. NAFTA cannot
be usefully separated from the set of trade liberalizing policies of which it is a part.
NAFTA's North American Commission for Environmental Cooperation, in its analytical
framework, calls for a broad interpretation of NAFTA's economic and environmental
impacts, noting that even where the agreement did not have a direct e
ect it may have sta-
bilized and reinforced trends already under way (NACEC 1999). Some analysts attribute
a smaller portion of rising US exports to NAFTA, arguing that some of these increases
would have occurred even without the tari
ff
reductions under NAFTA (see, e.g., Porter,
2002; Zahniser and Link, 2002). While I recognize the usefulness in some instances of iso-
lating those impacts that are directly attributable to NAFTA's provisions, here a broader
interpretation is used.
Environmental impacts of increased US corn production for the Mexican market fall
into four basic categories:
ff
1.
Intensive agrochemical use, with its resulting environmental impacts
2.
The increasing use of genetically modi
ed seed varieties, despite continued uncer-
tainty about their risks to human health or the environment
fi
3.
Unsustainable water use in areas where irrigation is needed
4.
Reduced biodiversity due to corn cultivation on grasslands and wetlands.
Looking
rst at chemical use, corn is one of the country's largest and most chemical-
intensive crops. Corn is planted on some 28 million hectares, 20 percent of all US har-
vested land, and 3.7 percent of the entire land area of the contiguous 48 states (Anderson
et al., 2000). Chemical fertilizers are used on the vast majority of US corn crops. The
runo
fi
ff
is a major source of water pollution, a
ff
ecting drinking water throughout the corn
belt in the center of the country. Runo
also pollutes rivers and streams. The great quan-
tities of nitrogen carried by the Mississippi river have been implicated in the large 'dead
zone' in the Gulf of Mexico where ocean life has been killed o
ff
ff
(Keeney and Muller, 2000;
