Fate and Distribution of the Herbicides 2,4-Dichloro-phenoxyacetic Acid (2,4-D) and 2,4,5-Trichlorophenoxy-acetic Acid (2,4,5-T) in the Dogfish Shark

Abstract

1. The urinary and biliary excretion, tissue distribution and metabolism of ¹⁴C-labelled 2,4-dichloro- or 2,4,5-trichloro-phenoxyacetic acids (2,4-D or 2,4,5-T) were measured in dogfish sharks, Squalus acanthias.

2. Both herbicides are extensively metabolized (> 90%) to the corresponding taurine conjugates, and are excreted predominantly via the urine, where ca. 70% of the administered dose appears within 4–6 days after treatment.

3. The highest tissue levels of 2,4-D or 2,4,5-T were found in liver and kidney. Penetration of both herbicides into the CNS was restricted.

4. Plasma elimination was rapid and the t_0.5 for either phenoxyacetic acid was < 45 min. Similarly, rapid clearance as seen from renal tissue. Final t_0.5 values for muscle were about 2–3 days while the major organ showing 2,4-D or 2,4,5-T retention was the liver, where t_0.5 values were about 5 days for both the herbicides.

5. The overall pharmacokinetics in the dogfish shark for these herbicides resembled those seen in some mammals.