Impacts of carbofuran on birds in Canada and the United State - Carbofuran and Wildlife Poisoning: Global Perspectives and Forensic Approaches - page 235

In at least one application, workers became ill after re-entering the fi eld on the day of spraying.
As argued by the US EPA (Fite, Randall, Young et al. 2006), it is inconceivable that foraging birds
should not be at risk from these applications when 150 pound mammals (i.e., people) with a much
lower sensitivity to the chemical are at risk of serious effects by merely entering those same fi elds.
8.4.4 Incidents
8.4.4.1 Incidents where birds were killed from grazing on treated vegetation
Birds that graze on freshly-treated vegetation are always in a high exposure situation. Observers
have reported grazing-related mortality of waterfowl and other species associated with several
organophosphorous and carbamates of high toxicity (Mineau 2003). Given its extreme toxicity to
waterfowl (as discussed in Chapter 2), it is not surprising that carbofuran has frequently been asso-
ciated with kills of grazing waterfowl. FMC also acknowledges the toxicity of their products to
waterfowl. For example, in the United States, labels for Furadan 4F had the following requirements:
• do not apply before or during furrow irrigation;
• do not apply on fi elds in proximity of waterfowl nesting areas; and
• do not apply on fi elds where waterfowl are known to repeatedly feed
The State of California (where there have been many waterfowl kills) treats any deviation from
the above as a misuse of the product subject to prosecution. Therefore, the State of California consid-
ers some of the kills reported here as technical misuses, putting the responsibility on the growers to
be aware of waterfowl feeding patterns in their areas. We note that California defi nes 'in proximity'
as one mile (1.6 kilometres) (Betts 1975).
Due to the small size of young waterfowl and the secretive habits of breeding waterfowl, it is
unlikely that anyone would witness kills of pre-fl edged individuals. Most of the documented water-
fowl mortality caused by Furadan 4F occurred when fl ocks of adult birds fed on treated crops, and
the kills were primarily in alfalfa fi elds.
In the US where the bulk of the grazing bird kills have been reported, the application rate of car-
boran in alfalfa range from 140 to 1120 g ai/ha.
8.4.4.1.1 May 1972, Lassen County, Susanville, California
Field personnel observed 13 dead Canada geese, and captured six geese that exhibited signs of poi-
soning (but later recovered). The incident report does not include the application rate. Investigators
found dead geese for 24 hours following application. Carbofuran residues in one alfalfa sample
were 15 ppm 60 hours post-application. One sample from a goose's proventriculus (the fi rst part
of the stomach where food is mixed before reaching the gizzard) contained 15.5 ppm carbofuran
(CDFG 1973).
8.4.4.1.2 March 1974, Riverside County, California
A farmer applied 580 g ai/ha carbofuran by ground. The alfalfa fi eld was less than 300 metres
from a reservoir and adjacent duck habitat used by a hunting club. The next day, observers found
about 2 450 American wigeon ( Anas Americana ), one mallard, and two Canada geese dead.
Carbofuran residues were present both in duck stomach contents (0.62 ppm) and collected alfalfa
(3.6 ppm). In response to the incident, the County Agricultural Commissioner banned the uses of
carbofuran in the area until the wigeon had departed. The California Department of Fish and Game
agreed to furnish the Agricultural Commissioner information about the presence of grazing water-
fowl that the Agricultural Commissioner could then consider before issuing permits to apply car-
bofuran. In addition, CDFG suggested to the US EPA that the Furadan 4F formulation be revised