Evaluating the MoA/human relevance framework for F-344 rat liver epithelioid granulomas with mineral oil hydrocarbons

Update of the risk assessment of mineral oil hydrocarbons in food

Mineral oil hydrocarbons (MOH) are composed of saturated hydrocarbons (MOSH) and aromatic hydrocarbons (MOAH). Due to the complexity of the MOH composition, their complete chemical characterisation is not possible. MOSH accumulation is observed in various tissues, with species-specific differences. Formation of liver epithelioid lipogranulomas and inflammation, as well as increased liver and spleen weights, are observed in Fischer 344 (F344) rats, but not in Sprague-Dawley (SD) rats. These effects are related to specific accumulation of wax components in the liver of F344 rats, which is not observed in SD rats or humans. The CONTAM Panel concluded that F344 rats are not an appropriate model for effects of MOSH with wax components. A NOAEL of 236 mg/kg body weight (bw) per day, corresponding to the highest tested dose in F344 rats of a white mineral oil product virtually free of wax components, was selected as relevant reference point (RP). The highest dietary exposure to MOSH was estimated for the young population, with lower bound-upper bound (LB-UB) means and 95th percentiles of 0.085-0.126 and 0.157-0.212 mg/kg bw per day, respectively. Considering a margin of exposure approach, the Panel concluded that the present dietary exposure to MOSH does not raise concern for human health for all age classes. Genotoxicity and carcinogenicity are associated with MOAH with three or more aromatic rings. For this subfraction, a surrogate RP of 0.49 mg/kg bw per day, calculated from data on eight polycyclic aromatic hydrocarbons, was considered. The highest dietary exposure to MOAH was also in the young population, with LB-UB mean and 95th percentile estimations of 0.003-0.031 and 0.011-0.059 mg/kg bw per day, respectively. Based on two scenarios on three or more ring MOAH contents in the diet and lacking toxicological information on effects of 1 and 2 ring MOAH, a possible concern for human health was raised.

Lack of human-relevant adversity of MOSH retained in tissues: Analysis of adversity and implications for regulatory assessment

Mineral oils (food grade white oil or liquid paraffin) have historically been safely used in a number of sensitive end-uses, including pharmaceutical, cosmetic and food. Recent concern that certain mineral hydrocarbons (branched and cyclo-alkanes) may accumulate in human tissues has prevented European Food Safety Authority (EFSA) from deriving guidance values for food exposures. Analysis of human and animal tissue indicate that an unresolved cloud of mostly highly branched alkanes and alkylated cycloalkanes within the C20-C35 range is consistently present in all tissues. This critical review thoroughly assesses the retention of "mineral oil saturated hydrocarbons" (MOSH) in human and animal tissues and evaluates if the presence of MOSH is considered adverse and appropriate to use for risk assessment, generation of guidance values for food exposure and/or generation of derivation of health-based guidance values. An adversity framework was utilized to perform an in-depth weight of the evidence analysis, and it was concluded that mere presence of MOSH does not translate to hazard identification, and is not considered adverse. In light of this conclusion, it would not be appropriate to utilize this endpoint as the point of departure to calculate a health guidance value.

Relevance of animal studies in the toxicological assessment of oil and wax hydrocarbons. Solving the puzzle for a new outlook in risk assessment

Paraffin waxes and white mineral oils are distinct petroleum products separated from a common feedstock by crystallization, where only n-alkanes, iso- and cyclo-alkanes with a linear backbone of ∼ 20 carbon atoms long, selectively crystalize out from the oil to form the wax, which is solid at room temperature, whereas oils remain liquid. Up until the 90's, these differences were reflected in separated regulatory assessments. A paradigm shift occurred when Fischer 344 rats (F-344) developed liver epithelioid granuloma following exposure to low and medium viscosity oils or waxes. This lesion was used as common denominator between these products to be jointly assessed under the common term "mineral hydrocarbons - MHC", obviating compositional differences. This regulatory paradigm dominated for the next 30 years, exacerbated by the EFSA 2012 evaluation using the analytical term "MOSH" (mineral oil saturated hydrocarbons) which encompassed these products under single chromatography fraction. The reconstruction of historical developments, together with recent EFSA-sponsored studies of toxicity and accumulation and supporting literature, has allowed us to understand the etiology of the F-344 rat hepatic epithelioid granuloma, which is presented in an adverse outcome pathway (AOP). Considering chemical composition, it clearly demonstrates that the hepatic effects in F-344 rats caused by linear alkanes of waxes are irrelevant for humans. Waxes are thus not MOSH and should thus be evaluated on their own merit. The term MOSH should not include n-alkanes and be exclusively used to mineral oil fractions when considering their chemical makeup for a relevant human hazard assessment.

Assessment of hazards and risks associated with dietary exposure to mineral oil for the Belgian population

Recently collected dietary exposure data on mineral oil saturated (MOSH) and aromatic (MOAH) hydrocarbons were used to evaluate the risks associated with exposure to mineral oil through food for the Belgian population. For MOSH, the no observed adverse effect level (NOAEL) value of 19 mg kg^-1 bw day^-1 based on the hepatic inflammation-associated granulomas found in a 90-day oral study in F-344 rats was used as point of departure (PoD). Due to existing toxicological uncertainties, the margin of exposure (MOE) approach was applied. In all investigated scenarios, the MOE values were well above 100, indicating that there is no direct health concern related to MOSH exposure for the Belgian population. Nevertheless, more appropriate risk assessment approaches for MOSH based on adequate PoD are needed. For dietary exposure to MOAH, which are potentially genotoxic and carcinogenic, no MOE values could be calculated due to the lack of adequate dose-response carcinogenicity data. In two investigated worst-case scenarios, a health concern related to MOAH exposure could not be excluded, highlighting that more data are needed to perform an adequate risk assessment. The possibility to use in vitro bioassays to collect such additional toxicological information for MOAH present in food samples was also investigated.

Dietary exposure to mineral oil hydrocarbons of Chinese infants aged 0-6 months

Consumers are exposed to a range of mineral oil hydrocarbons (MOH) via food. The potential adverse health effect of MOH varies widely. Since infant formula (IF) is the major food source for infants, it is necessary to understand MOH exposure and consequent health impact. In the present study, occurrence data of 42 IF samples and food consumption data of 0-6 months infants from China National Food Consumption Survey in 2015 were linked to evaluate the dietary exposure to MOH of 0-6 months infants in China. Ordinary consumers (who purchased IF for 0-6 months infants in different packaging type randomly), packaging type loyal- and brand loyal-consumers were selected as three representative populations. For ordinary consumers and packaging-loyal consumers, dietary exposure to MOH was estimated both deterministically and probabilistically. For brand-loyal consumers, point-estimation was used as the exposure assessment method. Due to toxicological gaps for MOHs, it was inappropriate to derive health-based guidance value and perform the robust human health risk assessment. MOE approach was used to characterise MOSH risk. The no-observed-adverse-effect level for induction of liver microgranulomas, 19 mg/kg BW per day, was used as a reference point for calculating margins of exposure (MOEs) for MOSH exposure. Although first exposure occurs in babies, there are no relevant toxicology studies. All MOE values for different scenarios were higher than 100. There are no dose-response data on the carcinogenicity of MOAH mixtures and hence it is not possible to establish a reference point to calculate the MOE and characterise its risk. Therefore, it is not possible to draw conclusions about the full nature of possible concerns for infants aged 0-6 months. This study evaluates by a probabilistic approach the dietary intake of Chinese infants aged 0-6 months to MOH for the first time and describes the associated uncertainties.

RT, Copland C, Giaquinto A, Juliano RA, Bhatt DL. Mineral oil: safety and use as placebo in REDUCE-IT and other clinical studies

Mineral oil is often used as a clinical trial placebo. Pharmaceutical-grade mineral oil consists of a mixture of saturated hydrocarbons, with a purity and chemical structure that differs substantially from food-grade or technical-/industrial-grade mineral oils. Interest in mineral oil was piqued by suggestions that a portion of the substantially positive results of the Reduction of Cardiovascular Events with Icosapent Ethyl-Intervention Trial (REDUCE-IT) might be attributable to the theoretical negative effects of mineral oil rather than being due to the clinical benefits of icosapent ethyl. The objective of this review was to explore possible mineral oil safety and efficacy effects and contextualize these findings in light of the REDUCE-IT conclusions. A literature search identified studies employing mineral oil placebos. Eighty studies were identified and relevant data extracted. Adverse events associated with mineral oil were generally gastrointestinal and consistent with use as a lubricant laxative. Changes in triglycerides, low-density lipoprotein cholesterol, high-density lipoprotein cholesterol, high-sensitivity C-reactive protein, and other biomarkers were inconsistent and generally not statistically significant, or clinically meaningful with mineral oil, as were changes in blood pressure. There was no consistent evidence that mineral oil in the amounts used in the REDUCE-IT or Effect of Vascepa on Progression of Coronary Atherosclerosis in Patients With Elevated Triglycerides on Statin Therapy (EVAPORATE) trials affects absorption of essential nutrients or drugs, including statins. These results were then considered alongside publicly available data from REDUCE-IT. Based on available evidence, mineral oil does not appear to impact medication absorption or efficacy, or related clinical outcomes, and, therefore, does not meaningfully affect study conclusions when used as a placebo at the quantities used in clinical trials.

Mineral oil in food, cosmetic products, and in products regulated by other legislations

For a few years, mineral oils and their potential adverse health effects have been a constant issue of concern in many regulatory areas such as food, cosmetics, other consumer products, and industrial chemicals. Analytically, two fractions can be distinguished: mineral oil saturated hydrocarbons (MOSH) and mineral oil aromatic hydrocarbons (MOAH). This paper aims at assessing the bioaccumulative potential and associated histopathological effects of MOSH as well as the carcinogenic potential of MOAH for consumer-relevant mineral oils. It also covers the absorption, distribution, metabolism, and excretion of MOSH and MOAH upon oral and dermal exposures. The use and occurrence of consumer-relevant, highly refined mineral oils in food, cosmetics and medicinal products are summarized, and estimates for the exposure of consumers are provided. Also addressed are the challenges in characterizing the substance identity of mineral oil products under REACH. Evidence from more recent autopsy and biopsy studies, along with information on decreasing food contamination levels, indicates a low risk for adverse hepatic lesions that may arise from the retention of MOSH in the liver. With respect to MOAH, at present there is no indication of any carcinogenic effects in animals dermally or orally exposed to highly refined mineral oils and waxes. Such products are used not only in cosmetics but also in medicinal products and as additives in food contact materials. The safety of these mineral oil-containing products is thus indirectly documented by their prevalent and long-term use, with a simultaneous lack of clinical and epidemiological evidence for adverse health effects.

Evaluating the risk to humans from mineral oils in foods: Current state of the evidence

Key issues around the evaluation of risks to humans from mineral oils in food and feedstuffs are discussed. MOHs (MOAH and MOSH) occur in food due to intentional use, contamination from environmental sources and during transport/processing, or through migration from food contact materials. Problems in setting and enforcing human health guidelines for MOH include uncertainty around MOH toxicity and the specialist expertise needed for analysis of complex food matrices. Currently, the method of choice for measuring mineral oils is LC-GC-FID, however some complex food matrices also require additional analytical techniques to differentiate between some naturally occurring hydrocarbons and those from other sources, including of petrogenic origin. This requires the skills of an experienced analyst. Significant toxicological gaps for MOHs prevent robust human health risk assessment and the derivation of guidance values. As food-grade mineral oils are virtually MOAH-free, the key issue explored here is the relevance to humans of liver (micro)granulomas observed in F344 rats following oral intake. Available data suggest that despite the ubiquitous nature of MOH in the human diet, the prevalence of liver lipogranulomas in the population is low. These are not associated with inflammation and based on current evidence are not considered of human health significance.

Dietary exposure of the Belgian population to mineral oil

Recently, presence of mineral oil in numerous foods has been detected. The analysis of mineral oil in food is convoluted since it comprises MOSH (saturated hydrocarbons) and variable amounts of mainly alkylated MOAH (aromatic hydrocarbons). Both fractions have a different toxicological profile and therefore they need to be assessed separately. For Belgium, occurrence data are available comprising concentrations of 217 food samples. These data were used, in combination with the 2014/15 Belgian Food Consumption Survey data, in a lower bound scenario to evaluate the dietary exposure of the Belgian population. Exposure to mineral oil was much lower compared to the results previously reported by EFSA and RIVM. The main contributors in Belgium were similar to previous studies (i.e. cereal products and oils), but an important additional contribution of non-alcoholic drinks was identified due to the presence of mineral oil in coffee. However, the concentration of mineral oil was determined from the dry product by applying a dilution factor with transfer rate of 100%, and not in the prepared coffee.This study gives an account of the dietary exposure of the Belgian population to mineral oil for the first time and reports the associated uncertainties.

Toxicological Assessment of Mineral Hydrocarbons in Foods: State of Present Discussions

The evaluation of mineral oils by the Joint FAO/WHO Expert Committee on Food Additives (JECFA) provided high acceptable daily intakes for classes largely falling into the mass range strongly accumulated by humans. Because they are roughly 2 orders of magnitude above the present exposure, they authorize strongly increased exposure. An approach based on accumulation seems more adequate. Increased organ weights might be more critical than granulomas. Aromatic hydrocarbons with 1-2 aromatic rings should be distinguished from those with at least 3 aromatic rings. If mineral oil saturated hydrocarbon limits were low, no limit might be needed for the 1-2 ring aromatics. It should be considered to phase out substantial use of mineral oils in food application.