# Toxicokinetic and Partial Mass Balance Assessment of 14C-Alpha Olefins in Rats

## TL;DR

This study examines how different alpha olefins are absorbed, distributed, and excreted in rats, showing that shorter-chain olefins are more readily absorbed and excreted in urine, while longer-chain ones are eliminated via feces.

## Contribution

The study provides new insights into the toxicokinetics and excretion patterns of alpha olefins based on chain length and lipophilicity.

## Key findings

- Shorter-chain alpha olefins (C8, C10) showed higher urinary excretion and greater systemic absorption.
- Longer-chain alpha olefins (C16, C20) were primarily eliminated via feces, indicating limited intestinal uptake.
- Adipose tissue retention increased with the chain length of the olefins.

## Abstract

Higher olefins are a class of alkenes widely used as intermediates in the production of essential consumer and industrial products. This radiolabel disposition and partial mass balance study investigated the distribution and excretion of four 14C-radiolabelled alpha higher olefins (i.e., 1-octene, 1-decene, 1-hexadecene, and 1-eicosene) in male Wistar rats following a single oral dose (100 mg/kg). Blood, liver, kidney, adipose tissue, urine, and faeces were collected and analysed for total 14C-derived radioactivity. Urinary elimination was rapid, with approximately 70% and 90% of total radioactivity recovered in urinary excreted within 24 and 48 h, respectively. Excretion patterns showed a clear chain-length-dependent trend: shorter-chain olefins (C8, C10) exhibited higher urinary excretion, indicating greater systemic absorption, while longer-chain olefins (C16, C20) were primarily eliminated via faeces, suggesting limited intestinal uptake. Tissue distribution was minimal in blood, liver, and kidney, but adipose tissue retention increased with chain length. Total recovery of administered radioactivity in the analysed matrices was low, ranging from 17% to 60%. Importantly, because exhaled 14CO2 and volatile parent compounds were not captured, the missing fraction cannot be quantified and the balance cannot be considered closed. All in all, the current study describes the partial disposition of higher olefins and highlights the influence of molecular size and lipophilicity on the biological fat, though further studies are required to fully characterise their metabolic profile and total elimination kinetics.