Preliminary studies on the bioavailability and disposition of bioincurred carrot residues of [¹⁴C] linuron and [¹⁴C]3,4‐dichloroaniline in rats

Abstract

Carrots grown from seed in soils spiked with [¹⁴C = O] linuron or [¹⁴C‐ring] 3,4‐dichloroaniline (DCA), were found to contain radioactivity equivalent to 0.73 ppm linuron or 0.60 ppm DCA. After exhaustive extraction with methanol these tubers still retained 35% and 67% of the original ¹⁴C‐bioincurred residues, for linuron and DCA respectively. To examine the bioavailability of these residues, rats were dosed by gavage (water vehicle) with unextracted tubers and extracted tubers. For comparison purposes ¹⁴C‐spiked carrot tubers and [¹⁴C] standards were also administered. Animals were maintained for 3 days in metabolism cages; urine, faeces, expired gases and several tissues were collected for radioassay. The following relative amounts of radioactivity (expressed as a percentage of the applied dose) were excreted (faeces/urine) for linuron or DCA dosing respectively: unextracted carrots, 28/31, 51/10; extracted carrots, 51/0, 73/3; spiked carrots, 11/43, 63/20; and linuron and DCA standards, 11/46, 26/81. The data demonstrated that approximately 31% and 10% of bioincurred ¹⁴C‐residues (from linuron and DCA respectively) in unextracted carrot tubers were bioavailable to rats. ¹⁴C‐Bound residues (extracted tubers) were much less bioavailable (0% and 3% respectively). The disposition of radioactivity in tissues, blood and expired gases was very low ( ≤ 1.3% per sample) for any dose studied.

Keywords:

• pesticide residues
• linuron
• 3,4‐dichloroaniline
• bioavailability
• carrot