Environmental Engineering Reference
In-Depth Information
A farmer had treated the cornfi eld with Furadan 10G the previous May or early June. The fi eld
had been fl ooded in sections in December and January to allow duck hunting. The farmer loaded the
planter at the opposite end of the fi eld from where most of the dead birds were found and unloaded
the planter once back at the farm. Thus, there was no indication of likely spills at the kill site, nor
was there evidence of careless use of the pesticide. Here it seems that the pesticide was suffi ciently
toxic to kill the waterfowl and subsequently cause poisoning via secondary exposure after seven
months of weathering in the fi eld. The investigators did not report the pH of the soil (California
Department of Fish and Game (CDFG) 1990a; Otsuji 1990).
8.2.2.2.9
Rice, California
Between 1984 and 1991, 31 kill incidents associated with the use of Furadan 5G were documented
in California rice fi elds. Field investigators recovered about 2 510 birds, mostly waterfowl but also
galliform species (e.g., American coot (
Fulica americana
)) and several bird of prey species (four
red-tailed hawks and one northern harrier), in those incidents (CDFG 1984a-c; CDFG 1985a-i;
CDFG 1986a-g; CDFG 1987; CDFG 1988a-c; CDFG 1989a-e; CDFG 1990c; CDFG 1990d; CDFG
1990k). A single incident in 1989 resulted in the loss of at least 1 700 waterfowl (CDFG 1989c).
Littrell (1988) presented 42 analyses of bird crop contents in which residue values ranged from
below detection to 640 ppm carbofuran in the gastrointestinal tracts. The median observed residue
level was 6.3 ppm.
At the time, the prevailing method was to apply the granules in the spring by air or ground to
prepared fi elds, after which the fi elds were fl ooded and the pre-wetted rice seed was applied by air.
Most of the mortality was recorded in the spring in freshly fl ooded fi elds. However, there were also
autumn kills on record. This is signifi cant because carbofuran was not registered for autumn use.
Thus, the kills in question were either due to a long-term persistence of the granules or a misuse of
the product. Littrell (1988) initially favoured misuse as an explanation of the kills, largely on the basis
that granules were not believed to persist to that extent. However, granules that fell above the water
line were found to persist on dry ground for several months. In autumn, fi elds were fl ooded to attract
waterfowl. Authorities determined that spillage of granules during mixing and loading operations
in the spring was partially responsible for the losses. Consequently, the rice industry and regulatory
agencies developed and implemented a stewardship programme which included Best Management
Practices (BMP) such as incorporation of granules into the soil. Since implementation of these BMPs,
CDFG received only two reported incidents of bird kills after 1991 (CDFG 1993g; CDFG 1995a).
8 .2.2.2.10
May 1997, spinach, Stanwood, Washingon
As noted earlier, the granular formulations were retained for the use of spinach grown for seed pro-
duction following the 1991 negotiated agreement between the US EPA and the manufacturer. Fite,
Randall, Young et al. (2006) report a kill of several hundred dunlins (
Calidris alpine
) in a treated
spinach fi eld. Unfortunately, no further details are provided. This is a highly interesting case because
it underlies the risk of allowing dangerous registrations to persist, even in minor crops and for minor
uses. The fact that the casualties are shorebirds, more commonly seen on beaches and tidal fl ats,
makes this incident that much more intriguing. Based on the life habits of dunlins, we opted to place
the incident in the section on the risk of puddling - but the association is pure conjecture at this point.
8.3 Impacts from the corncob granular formulation
Compared to the silica granule, relatively fewer studies have addressed potential repercussions with
the corncob formulation. FMC conducted an extensive study in Manitoba and Saskatchewan for the
Canadian Regulatory Agency.
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