Toxicological and ecotoxicological properties of gas-to-liquid (GTL) products. 1. Mammalian toxicology

Abstract

Gas-to-liquid (GTL) products are synthetic hydrocarbons produced from natural gas using a Fischer-Tropsch process. This process yields a synthetic crude oil that consists of saturated hydrocarbons, primarily linear alkanes, with increasing amounts of branched (methyl-groups) alkanes as the chains get longer. In addition, small amounts of cycloalkanes (branched cyclopentanes and cyclohexanes) may be formed as the polymerization reaction prolongs. This synthetic crude can subsequently be refined to a range of products very similar to petroleum refining. However, in contrast to their petroleum-derived analogs, GTL products are essentially free of unsaturated or aromatic constituents and also no sulfur-, oxygen-, or nitrogen-containing constituents are present. From a regulatory perspective, GTL products are new substances which require extensive testing to assess their hazardous properties. As a consequence, a wide range of GTL products, covering the entire portfolio of GTL products, have been tested over the past few years in a wide variety of toxicological studies, including reproductive and prenatal development toxicity studies. This review provides an overview of the hazardous properties of the various GTL products. In general, the data collected on GTL products provide strong proof that they exert minimal health effects. In addition, these data provide supporting evidence for what is known on the mechanisms of mammalian toxicology of their petroleum-derived analogs. In the few cases where adverse effects were found for the GTL substances, these were usually less severe than the adverse effects observed with their petroleum-derived analogs.

The role of metabolism in the developmental toxicity of polycyclic aromatic hydrocarbon‐containing extracts of petroleum substances

“…These data suggest that bioactivation may play a minor role in the in vitro PDT of these PS extracts used as model compounds. GTLb extracts remained unable to induce any effect in the EST regardless of the presence or absence of preliminary metabolic activation, which is in line with the absence of PAHs in these substances (Boogaard, Carrillo, Roberts, & Whale, 2017;Kamelia et al, 2019Kamelia et al, , 2017. To add, the results obtained in the present study for the extracts incubated without microsomes are comparable with our previous published data (Kamelia et al, 2019) on the same PS and GTLb extracts tested in the ES-D3 cell differentiation assay of the EST as such (see Appendix G; see Supporting Information).…”

“…Hence, future studies may consider the influence of structural features and size of For bioactivation of the PAHs and PAH-containing PS, the present study made use of hamster liver microsomes as it has been shown that they are more effective for bioactivation of these groups of substances in comparison with rat or mouse liver microsomes (Blackburn et al, 1986;Haugen & Peak, 1983;Hermann, 1981;Hermann et al, 1980). For instance, Blackburn et al (1986) modified the standard Ames test, later known as the modified Ames test, for mutagenicity testing of PS by (1) using hamster rather than rat liver S9 mix for generating metabolite mixtures of PS, and (2) using DMSO extracts of PS instead of neat/bulk materials, which improved the interaction of potentially toxic constituents present in PS with the aqueous in vitro test system. Using the above-mentioned modifications, Blackburn and co-workers were able to assess correctly the mutagenicity potency of 18 PS samples from different product categories (Blackburn et al, 1986).…”

Toxicological and ecotoxicological properties of gas-to-liquid (GTL) products. 2. Ecotoxicology

“…Part 1 of this review presented the mammalian toxicology data on GTL products and compares these to similar data obtained with conventional, petroleum-derived products (Boogaard et al 2017). In this second paper, the ecotoxicological data generated on GTL products for aquatic, sediment, air (avian) and terrestrial dwelling organisms will be presented.…”

“…The results of the avian studies in which no GTL product related adverse effects were seen even at high (5000 mg/kg) doses would have been anticipated based on the lack of significant adverse mammalian toxicity in gavage studies as reported by (Boogaard et al 2017). No further long-term avian toxicity studies were undertaken as these were not warranted based on exposure patterns and the lack of toxicity found in acute tests with the GTL Fuel and GTL Base oil.…”

The Role of Endocrine and Dioxin-Like Activity of Extracts of Petroleum Substances in Developmental Toxicity as Detected in a Panel of CALUX Reporter Gene Assays

“…The main manifestations of this adverse effect include increased incidence of resorptions, reduced number of live fetuses per litter, decreased fetal body weight, and increased incidence of skeletal variations of the fetuses ( Feuston and Mackerer, 1996 ; Feuston et al , 1994 ; Hoberman et al , 1995 ). However, reproductive and developmental toxicity studies with gas-to-liquid (GTLs) products, modern synthetic analogs of PS, containing only saturated hydrocarbons and devoid of aromatics, showed no PDT or reproductive toxicity ( Boogaard et al , 2017 ; Dunster, 2014 ; Senn, 2014 ). Hence, it is hypothesized that heavy- and poorly refined PS with relatively high concentrations of certain PAHs may induce PDT while light- or highly refined PS with no or very limited amounts of PAHs will not induce PDT ( Tsitou et al , 2015 ).…”