Environmental Engineering Reference
In-Depth Information
blue. This material is deposited directly into the seed furrow (in-furrow) or applied as a wide strip
(banded) over the seed furrow but extending approximately 10 cm on either side. This wider band is
designed to provide protection to the developing tap roots of the maize as the insecticide, dissolved
in rain water, percolates into the soil.
In Canada, through a commercial arrangement with FMC, the Bayer Corporation also sold 5 and
10% granules on a corncob base (granulated dried maize cob) for use in oilseeds (canola or oilseed
rape and mustard) at seeding. Bayer marketed the 10% granule as Furadan CR-10. These granules
are slightly larger and more angular in shape - more like fi ne gravel; therefore they do not 'fl ow' as
well as the silica granules. They are mixed with and planted directly with the seed, typically canola
(oilseed rape).
In the United States, the Environmental Protection Agency (US EPA) began its re-evaluation of
granular formulations of carbofuran in 1985, after FMC conducted a fi eld study in Utah (described
later in 8.2.1.2). This study showed substantial mortality, in line with the predicted risk from the
original assessment. The US EPA and the manufacturer (FMC) reached a negotiated settlement in
1991, leading to the gradual phaseout of the main use patterns. However, as recently as 2002, the
agency proposed relaxing restrictions for emergency use in rice (where a State requests a supple-
mentary registration on the basis of a perceived agronomic necessity), which some environmental
groups contested. These emergency uses were eventually denied. The use of Furadan 4F continued
until 2009, despite ample evidence from industry fi eld studies mandated by the agency and submit-
ted in 1989 that the product caused regular and predictable avian mortality. Effective from December
2009, the US EPA revoked all tolerances for carbofuran, effectively prohibiting all uses on food
crops. The EPA also issued an 'Intent to Cancel' notice for carbofuran, and has now cancelled
all uses. Evidence of ecological effects, including wildlife kills, was considered in this decision as
well as risks to human health.
Soon after farmers began using carbofuran in Canada in 1973, reports of bird kills started coming
in. Field investigators documented at least four different incidents in British Columbia (BC) between
1973 and 1975 that involved a total of more than 1 300 bird deaths. There was substantial unfavour-
able publicity associated with these bird kills, and, in 1976, FMC withdrew the 10G formulation
from BC. Flooded fi elds, slow breakdown of granules in acidic soils, and extensive use of agricul-
tural fi elds by waterfowl exacerbated the risk to bald eagles (
Haliaeetus leucocephalus
) and other
birds of prey (see Section 8.5, further on). Notwithstanding the history of bird die-offs, agricultural
authorities encouraged FMC to reintroduce the product in 1986 (P.W. McMullen, Chemagro Ltd.,
personal communication). A kill of 500 to 1 200 songbirds occurred that same year in a turnip (ruta-
baga) fi eld, and it is likely that more waterfowl and scavengers died.
In response to continuing pressure from the Canadian Wildlife Service (CWS) of Environment
Canada, Canadian regulatory authorities announced a special review of both granular and liquid
formulations in June 1990 (Agriculture Canada 1990). The present chapter takes its root in an unpub-
lished report (Mineau 1993) that reviewed the demonstrated impacts on birds of both the granular
and liquid formulations of carbofuran in Canada and the US. That report formed the basis of the
Canadian case for regulatory review of the product by the Canadian Department of Agriculture
(the regulatory authority at the time). For that review, Mineau (op. cit.) examined all original investi-
gation and incident reports so as to provide as much detail as possible to the regulators. For incidents
documented after that date with the fl owable formulation, we relied largely on a compilation by the
US EPA (Fite, Randall, Young et al. 2006); therefore, these accounts are less complete. In the pres-
ent chapter, we only review fi eld studies and incidents. A few small pen (i.e., simulated fi eld) tests
have also been performed with this insecticide (e.g., Martin, Solomon, Forsyth et al. 1991; Somers,
Kumar, Khan et al. 1991; Martin and Forsyth 1993; Martin, Johnson and Forsyth 1996) but their
inclusion would require a more in-depth review of simulated fi eld tests and whether they accurately
portray actual exposure. We have therefore chosen to omit them. Other reviews of the impacts of
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