Environmental Engineering Reference
In-Depth Information
8.3.2.2 September 1988, canola, Jeanette's Creek, Ontario
A farmer used rapeseed premixed with Furadan CR-10 as a cover crop for soil conservation, apply-
ing the seed and granules with a clover seeder starting at 09:30 and harrowing between 14:30 and
17:00 the same day. A neighbour reported the bird mortality six days later. At that time, fi eld inves-
tigators estimated that about 200 to 300 sparrows and 'blackbirds' (mixed fl ocks of several species)
were left on the fi eld during the investigation (Collins 1988). The actual kill, before any carcasses
were scavenged, was likely much larger. A composite sample of pooled crop contents contained 7
ppm carbofuran (Brash and Barker 1988).
Again, in this incident the farmer had broadcast the seed on the surface and then harrowed. Based
on the case presented in 8.3.2.1 and available engineering research, this method of granule incorpo-
ration actually leaves fewer granules on the soil surface than some of the recommended seed drills.
8.3.2.3 May 1994, Wolseley, Saskatchewan
A homeowner found 15 dead American goldfi nches (
Carduelis tristis
) while mowing the lawn.
While the property was in a canola growing area, it was not clear where the birds were exposed to
carbofuran. We could not rule out a spill of seed on the road as seeders are often moved from one
fi eld to another and seed might have spilled. Cholinesterase data suggested carbamate intoxication,
and we verifi ed the presence of carbofuran in two of the three samples analysed by the labora-
tory. (For reasons of economy, it is typical to only carry out a few residue analyses for any given
incident, even in relatively affl uent North America.) The pathologist reported small seed resembling
canola seed in the crops of the birds. Lindane residues were also detectable in one bird, suggesting
that this compound was used as a seed treatment at the same time that carbofuran granules were
added to the seed, which was a usual procedure (Mineau 1994).
8.4 Impacts from the fl owable (liquid) formulation
There is ample evidence linking the use of the liquid formulation of carbofuran to bird kills. This
includes company studies mandated by the US EPA, other fi eld studies (primarily in Canada), sur-
veillance programmes and incident reports. The latter were obtained primarily from US EPA docket
fi les but we consulted other information where relevant. We omitted cases where carbofuran had
been tank-mixed with other insecticides even though we can often surmise about the relative contri-
bution of each insecticide based on its inherent toxicity and concentration.
8.4.1 Industry-supervised fi eld trials
The most extensive fi eld studies available for fl owable carbofuran are those conducted by the manu-
facturer, at the behest of the US EPA. These studies are basically carcass searches conducted in
cornfi elds and alfalfa fi elds. They are briefl y reviewed here. The most recent review of these same
studies (as well as some of the other studies reviewed in this chapter) by the US EPA can be found
in Fite, Randall, Young et al. (2006).
8.4.1.2 FMC 1983: alfalfa, Utah
FMC conducted this study concurrent with the study on corn granulars reported in Section 8.2.1.2.
The results of the study were diffi cult to interpret because key information was missing. Also, the
total carcass search effort was minimal relative to the effort needed to ascertain whether there was
mortality associated with the pesticide. The US EPA, in their recent review (Fite, Randall, Young
et al. 2006) similarly dismissed this study.
Search WWH ::
Custom Search