Transfer of DDT and Metabolites from Fruit Orchard Soils to American Robins ( Turdus migratorius ) Twenty Years After Agricultural Use of DDT in Canada

Abstract

Wildlife contamination studies found high levels of DDT and associated metabolites in bird eggs from Canadian orchard sites during the early 1990s. The present study investigated local dietary uptake of DDT and geographic variability in tissue concentrations in the same orchards. A soil-earthworm-robin food chain was chosen for study, as early surveys showed that robins contained the highest levels of DDT of several avian species and because published research indicated that earthworms were a probable dietary exposure route. Organochlorine pesticides and PCBs were measured in soil, earthworm, robin egg, and robin nestling samples collected from fruit orchards and reference sites. High average DDE (soil: 5.2 mg/kg; earthworm: 52 mg/kg; robin egg: 484 mg/kg dry weight) and DDT (soil: 9.2 mg/kg; earthworm: 21 mg/kg; robin egg: 73 mg/kg dry weight) concentrations in Okanagan (British Columbia) samples confirmed that previously recorded contamination was common in the region. Concentrations detected in Simcoe, Ontario, orchards were not as high but were still significantly elevated relative to levels in soils and robins from reference areas. Significant positive linear regressions between soil and earthworm concentrations and consistent trends in food chain accumulation suggested that robins were acquiring DDT and metabolite (DDTr) burdens locally. Low concentrations of DDT and DDTr in robin eggs collected from nests in nearby nonorchard and post-DDT orchard habitats suggested that the local sources were in orchards. Persistence of DDT in orchard food chains is likely due to a combination of retarded degradation rates for DDT in soil and its extensive use historically. DDT concentrations in some robin eggs and earthworms were at levels comparable to those observed in field studies where mortality or reproductive effects occurred.

Persistence and Changes in Bioavailability of Dieldrin, DDE, and Heptachlor Epoxide in Earthworms Over 45 Years

“…Concentration factors measured in recent studies are in the same range. As part of a study examining the bioaccumulation of DDE in robins inhabiting orchards in Canada, Harris et al (2000) reported average DDE concentration factors (dry weight) of 3.77-5.21 at their three sites. Earthworms from parks in Beijing, China, had a median DDT (sum of all compounds) concentration factor (dry weight) of 7.47 (Li et al 2010).…”

“…Both of these topics are useful to risk assessors. Although most uses of these insecticides were cancelled in the 1970s, they remain biologically available to wild birds over widespread areas (Harris et al 2000) and are still the cause of fish advisories (New Department of Health 2012). They were the contaminants of concern at a minimum of 312 active EPA superfund sites 49 in 2011 (Search Superfund Site Information 2012).…”

Organochlorine pesticides (DDTs and HCHs) in soils from the outskirts of Beijing, China

“…6) showed that highest DDT/DDE ratios for the shallow subsurface soils and deep layer soils were located at the southwest and southeast sites, respectively, where high DDTs levels were found. Extremely high ratios were found in the deep layer soils, probably because of the long-term leaching of p,p 0 -DDT and retarded degradation of DDT to DDE in the deep layer soils (Miglioranza et al, 1999;Harris et al, 2000). Great proportions of p,p 0 -DDT were also observed in agricultural soils of central Germany (Manz et al, 2001) and of southern Ontario (Meijer et al, 2003), and in some western USA soils (Hitch and Day, 1992).…”

“…The origin and fate of OCPs in soils with different land use have been extensively studied in many countries. Although the usage of OCPs was phased out for decades, the elevated concentrations were still observed in many agricultural soils (Szeto and Price, 1991;Harris et al, 2000) and the relationship between sites of greatest application and current residue levels was found strong (Shivaramaiah et al, 2002). The release of OCPs from soils continues to be a source to the environment (Munn and Gruber, 1997;Meijer et al, 2003).…”

Organochlorine Pollutants and Stable Isotopes in Resident and Migrant Passerine Birds from Northwest Michoacán, Mexico

“…Although concentrations of organochlorine compounds (OCs) in birds from most of the United States and Canada have decreased over the last 30 years, there is still concern that migrant birds might be exposed to elevated concentrations of persistent organochlorine pollutants (POPs) in Latin America. DDT [1,1,1-trichloro-2,2-bis(p-chlorophenyl)ethane] was banned in the United States in 1972 and shortly thereafter in Canada (Harris et al 2000). Agricultural use of DDT in Mexico was discontinued around 1978(Fertilizantes Mexicanos 1981; however, DDT use for malaria control and other public health campaigns continued until around 2000 (Chanon et al 2003;http://www.cofepris.gob.mx/bv/libros.htm, December 4, 2006).…”