Granulomas in the livers of humans and fischer rats associated with the ingestion of mineral hydrocarbons: A comparison

Toxic effects of mineral oil saturated hydrocarbons (MOSH) and relation to accumulation in rat liver

Humans are daily exposed to mineral oil saturated hydrocarbons (MOSH) from the diet. We exposed female Fischer 344 rats to a broad mixture and sub-fractions of MOSH. Chemical characterization of the MOSH mixture used and material accumulated in rat tissues were previously reported (Barp et al. 2017a, 2017b). Rats were exposed to feed containing 0-4000 mg/kg broad MOSH mixture for 30, 60, 90 and 120 days; and for 120 days to feed containing different MOSH fractions: i) mainly molecular masses < C25 (S-C25), ii) dewaxed, mainly molecular masses > C25 (L-C25) and iii) the L-C25 fraction mixed with wax largely consisting of n-alkanes > C25 (L-C25W). Treatments related effects were increased liver and spleen weight, as well as vacuolization and granuloma formation with lymphoid cell clusters in the liver, but effects varied strongly between the MOSH fractions tested. We conclude that increased liver and spleen weights were related to accumulated n-alkanes (wax) above C25, presumably not relevant for humans, but also to MOSH from S-C25, mainly consisting of iso-alkanes and substituted cycloalkanes below C25 with a small proportion of n-alkanes. Induction of liver granuloma appeared to be related to n-alkanes > C25 and not to the accumulated amount of MOSH. Immune responses to an injected antigen were not affected. Iso-alkanes and substituted cycloalkanes accumulating in rat liver and spleen were similar to those accumulating in humans.

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.

GTL synthetic paraffin oil shows low liver and tissue retention compared to mineral oil

Oral exposure to mineral oil may result in a narrow fraction of mineral oil saturated hydrocarbon (MOSH) being retained in tissues. Excess of MOSH hepatic retention may lead to the formation of lipogranuloma caused by predominantly multiring cycloalkanes (naphthenics) in a critical range of C₂₅-C₃₅. Although hepatic lipogranuloma is of low pathological concern, MOSH tissue deposition could be minimized by using an oil of similar quality but devoid of naphthenic structures to decrease hepatic retention. Synthetic Gas to liquid (GTL) oils offer an alternative to petroleum derived mineral oils, because they do not contain naphthenic structures. To demonstrate this point, SD rats were fed either GTL oil (99% iso-alkanes) or naphthenic mineral oil (84% cycloalkanes) at 200 mg/kg bw/day for 90 or 134 days with a recovery group. Liver, fat and mesenteric lymph nodes were analyzed for alkane sub-type levels using Online-HPLC-GC-FID and GCxGC-TOF-MS. Results indicate that at equal external dose, GTL hydrocarbons result in lower tissue levels and more rapid excretion than MOSH. GTL retained hepatic fractions were also qualitatively different than MOSH constituents. Because chemical composition differences, GTL oil show low absorption and tissue retention potential and thus an advantageous alternative to conventional mineral oil.

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.

Results of Chronic Dietary Toxicity Studies of High Viscosity (P70H and P100H) White Mineral Oils in Fischer 344 Rats

Two-year dietary studies were conducted to determine the chronic toxicity and its reversibility, and the carcinogenicity of P70(H) and P100(H) white mineral oils in Fischer-344 rats (F-344). The studies were identical in design and followed the Organization for Economic Cooperation and Development, Guidelines for Testing Chemicals, Guideline 453, 1981. Additional endpoints evaluated were: (1) extent of mineral hydrocarbon deposition in liver, kidneys, mesenteric lymph nodes, and spleen of female rats at 3, 6, 12, 18 and 24 months, and (2) reversibility of effects following cessation of exposure. Dietary concentration were 60, 120, 240, and 1, 200 mg/kg/day, adjusted periodically to account for bodyweight changes. Study results were consistent with preceding subchronic studies. No treatment-related mortality, neoplastic lesions, or changes in clinical health, hematology, serum chemistry, or urine chemistry were evident in any group administered either white oil. Statistically significant higher food consumption was noted in the 1, 200 mg/kg group males and females exposed to either white oil and statistically significant higher body weights were noted in the 1, 200-mg/kg males during the latter portion of the P100(H) study. Higher mesenteric lymph node weights were accompanied by increased severity of infiltrating histiocytes. This occurred to a greater extent with the P70(H) than the P100(H) oil. No other histopathology of significance was observed. Mineral hydrocarbons were detected in the liver following exposure to either oil. Maximal concentrations of mineral hydrocarbons in the liver were similar with both oils but occurred more rapidly with the P70(H) oil. Liver mineral hydrocarbon content returned to near-background levels during the reversibility phase. In conclusion, lifetime exposer of F344 rats to P70(H) and P100(H) white oils resulted in only minimal findings and with no consequence to clinical health. Thus, under the conditions of these studies, the No Observable Adverse Effect Level (NOAEL) for these studies was considered to be 1, 200 mg/kg/day.

Do Claims about the Naturalness and Dose of Cosmetics Ingredients Affect the Public’s Perception of Their Safety?

Media articles have claimed that “synthetic mineral oil saturated hydrocarbons (MOSH)”, which are used in many cosmetics such as lip balms, are unsafe at any dose and should be replaced with natural alternatives. This paper examines whether these claims are correct and whether the perceived safety of these substances is influenced by the language used in the media. To achieve these goals, it first provides an extensive review of the toxicology literature, finding no support that MOSHs are unsafe at current usage levels. It then reviews the psychology literature to examine the effects of labelling a cosmetic ingredient as “natural” rather than “synthetic” and the effects of dose information. A 2 × 2 between-subjects experiments involving adult lip balm users shows that, as hypothesized, the perceived safety of lip balms increases when they are described as containing “naturally sourced mineral oil” rather than “synthetic mineral oil saturated hydrocarbon (MOSH)”, which are both correct descriptions. In addition, the perceived safety increases when the substance is described as being present in a low vs. a high dose, regardless of whether it was described as natural or synthetic. Overall, safety perceptions for common cosmetic substances can be significantly influenced by the language used in media reporting.

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.

Transformer mineral oil ingestion induces systemic sub-acute toxicity in Wistar rats

We investigated the potential toxicities associated with the sub-acute ingestion of transformer mineral oil (TMO) at a heated low dose (HLD-50 mg/kg), heated high dose (HHD-500 mg/kg) and unheated high dose (UHD-500 mg/kg) in Wistar rats. There were increases in red blood cells and haemoglobin levels in HHD females and UHD males respectively versus control. The serum total proteins, albumin, and creatinine of the HHD females showed a significant increase versus control. The HHD males and UHD groups showed significant increase in liver malondialdehyde versus control. The livers of HHD groups had bile duct proliferation while those of HLD females and UHD groups showed focal areas of periportal chronic inflammation. HHD groups had kidneys with mild chronic inflammation and the HHD and UHD groups showed small intestines with chronic inflammation. In conclusion, sub-acute oral administration of TMO induced various degrees of dermal, haematological, hepatic, renal and small-intestinal toxicities in rats.

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.

Mineral oil saturated hydrocarbons (MOSH) in female Fischer 344 rats; accumulation of wax components; implications for risk assessment

Female Fischer 344 rats were exposed to three MOSH mixtures: oils largely below and above C₂₅ (S-C25 and L-C25) and a 1:1 mixture of L-C25 with a wax; doses of 400, 1000 and 4000mg/kg feed were administered during 120days. MOSH were determined by on-line HPLC-GC-FID in liver, spleen, adipose tissue and the carcass. The composition of the hydrocarbons accumulated in the tissues was further analyzed by comprehensive two-dimensional GC (GC×GC). MOSH in the mass range of C_26-30 were more strongly accumulated than those between C_20-25, which does not support the present classification of MOSH differentiating at n-C₂₅ for risk assessment. Compared to the total of the MOSH, n-alkanes and n-alkyl monocyclic naphthenes were generally enriched in adipose tissue. In liver and spleen, n-alkanes up to C₂₅ were eliminated, but strongly accumulated at around C₃₀. Based on this profile, poor solubility and the melting points, it is hypothesized that crystallization protects these wax components against metabolism and elimination. In the liver, relative retention of n-alkanes decreased again beyond C₃₀, accentuated at high exposure, suggesting reduced absorption. Compared to the animal data, accumulation of n-alkanes from food sources, such as apples, into human tissues seems low, perhaps because of low absorption due to their presence in crystalline form. A series of dominant isoalkanes, accumulated in all tissues analyzed, was characterized, though without proposing a structure. Implications on present regulation of white mineral oil products are discussed.

Hypercalcemia associated with mineral oil-induced sclerosing paraffinomas

OBJECTIVE

Granuloma-forming diseases such as sarcoidosis are associated with extrarenal synthesis of 1,25-dihydroxyvitamin D [1,25(OH)₂D]. We describe a case of extensive skin lesions associated with mineral oil injections in which we provide evidence for cutaneous granuloma synthesis of 1,25(OH)₂D in the pathogenesis of the patient's hypercalcemia.

METHODS

Analysis of expression of the 25(OH)D-1a-hydroxylase (1-a OHase [CYP27b1]) was carried out by immunohistochemical analysis of involved skin.

RESULTS

In involved skin, expression of CYP27b1 was found in the dermis, where it is not normally expressed. Successful management of hypercalcemia was achieved with glucocorticoids.

CONCLUSIONS

Hypercalcemia associated with mineral oil induced skin lesions is likely driven by unregulated expression of CYP27b1 by inflammatory monocytes and macrophages infiltrating the dermis.

Histopathologic manifestations of drug-induced hepatotoxicity

Drug-induced hepatotoxicity is underrecognized but increasingly identified as causing acute and chronic liver disease. Several prescription drugs, over-the-counter medications, dietary and/or supplementary agents, and herbal products are hepatotoxic. Drug-induced liver injury mimics other primary acute and chronic liver diseases and it should be considered in patients with hepatobiliary disease. Certain drugs result in specific histopathologic patterns of liver injury, which may help in sorting out the responsible drug. The diagnosis of drug-induced hepatotoxicity is challenging. It involves excluding other possible causes, careful medication history, the latent period between drug exposure and symptom onset and/or abnormal liver tests, and histopathologic findings.

The effects of long-term exposure to ozokerite mainly consisting of an aliphatic series of hydrocarbons using F344 rats

Combined chronic toxicity and carcinogenicity studies of ozokerite (OZK), a natural wax substance used as a food additive for a gum base, were performed in male and female F344 rats. Dietary concentrations of 0%, 0.05%, 0.1% and 0.2% OZK were applied in a 52-week chronic toxicity study and 0%, 0.1% and 0.2% in a 104-week carcinogenicity study. In the chronic toxicity study, treatment with OZK caused a xenobiotic reaction against absorbed OZK, including formation of histiocytosis and granulomas with crystalline material in many organs in all of the treated males and females. Particularly in the liver, granulomatous inflammation was accompanied by hepatocellular vacuolation and changes in the serum biochemical parameters indicative of hepatic disorder. The number and area of glutathione S-transferase placental form (GST-P) positive foci were increased in all of the treated groups of both sexes, suggesting the proliferative effect of OZK. In the carcinogenicity study, the incidence of hepatocellular adenoma and the total tumor incidence in the liver of all of the treated males were significantly increased compared with the controls. In conclusion, long-term exposure to OZK caused systemic chronic inflammation due to a foreign body response. OZK was weakly carcinogenic in the liver of male F344 rats.

Immunotoxicity of nucleic acid reduced BioProtein--a bacterial derived single cell protein--in Wistar rats

BioProtein is a single cell protein produced by a mixed methanotrophic and heterotrophic bacteria culture using natural gas as energy source, which has been approved for animal feed. BioProtein contains a large amount of nucleic acids making the product less suitable for human consumption, therefore, a nucleic acid reduced variant (NABP) has been developed by the manufacturer. The purpose of the present study was to establish the safety of NABP in a subchronic toxicity rat study. Groups of 10 male and 10 female Wistar rats were fed diets containing 0, 6, 12 or 24% NABP for 13 weeks. Feeding NABP induced a humoral immune response and proliferation of phagocytic cell lines, mainly macrophages. The humoral response involved induction of NABP specific IgM and IgG. The proliferation of phagocytic cells involved increase of the white blood cell count of all dosed female groups. Males showed the same tendency, although, not statistically significant (P=0.09). The subsets of cells identified as neutrophils and eosinophils were increased and lymphocytes decreased. The histopathological examination revealed histiocytosis and accumulation of foamy macrophages in the mesenteric lymph nodes, hyperplasia of Kupffer cells in the liver, increased granulopoiesis in spleen and bone marrow, and infiltration of lamina propria of the large intestine with eosinophilic granulocytes. The most consistent and pronounced changes were observed in the highest dose group, but even at the lowest dose level some of the changes were present. Accordingly, a no-observed-effect level could not be established based on this study.

Assessment of the morphology and significance of the lymph nodal and hepatic lesions produced in rats by the feeding of certain mineral oils and waxes. Proceedings of a pathology workshop held at the Fraunhofer Institute of Toxicology and Aerosol Research Hannover, Germany, May 7-9, 2001

A Panel of medical and veterinary pathologists reviewed published and unpublished reports dealing with studies of various white mineral oils and waxes in F344 and Sprague-Dawley rats. They also had available and studied histologic slides from both subchronic and chronic studies of certain mineral hydrocarbons (90-day oral study of low melting point wax (LMPW) in female Fischer 344 and Sprague-Dawley rats; 90-day studies of P15H* and P70H white oil and high melting point wax (HMPW) in male and female F344 rats and 24 month study of P70H white oil in male and female F344 rats. The Panel also reviewed mineral oil-induced alterations in tissues of human patients (liver, hepatic lymph node and spleen). The Panel agreed that certain of the mineral hydrocarbons produced lesions in the mesenteric lymph nodes and liver of the F344 rat and these lesions were best described as microgranulomas/granulomas. The lesions were fundamentally similar in both organs, although varying in severity with dose and type of mineral hydrocarbons. The Panel agreed that hepatic lesions with inflammatory cell infiltration, necrosis, and fibrosis were produced only by feeding of LMPW and the lesions were confined to F344 rats and not found in Sprague-Dawley rats. The most severe granulomatous lesions in the mesenteric lymph nodes were found in high dose LMPW-fed F344 rats. The microgranulomas were similar in subchronic and chronic studies. Also, little difference existed between controls and treated F344 rats in the incidence and severity of the lesions after 2 years of feeding P70H white oil. The Panel agreed that some slight reversibility existed for these lesions, but also agreed that complete resolution was unlikely as regression of the lesions in the rat would likely be slow. The Panel agreed that a minimal severity infiltrate of mononuclear inflammatory cells occurred in the base of the mitral valve in a slightly increased incidence in F344 rats fed LMPW. The Panel concluded that these mitral valve alterations had little if any toxicologic significance as the focal infiltrate was minimal in severity, occurred in controls, occurred in association with murine cardiomyopathy, and were unlike the responses in the liver and mesenteric lymph nodes. The Panel agreed that the lesions observed in the liver and mesenteric lymph nodes of F344 rats exposed to MHCs, especially the LMPW, were different morphologically from changes observed in lymph node, liver, and spleen of humans that were mineral oil-users. These changes in humans are usually found incidentally in tissues taken at biopsy or autopsy. The MHC-induced lesions can be considered incidental and inconsequential in humans.

Short-term adverse effects in humans of ingested mineral oils, their additives and possible contaminants--a review

The toxicological databases for petroleum refinery products such as mineral oils, as well as for their potential contaminants and additives, were reviewed for human cases of poisoning by the oral route. The aim was to determine whether any overlooked adulterant in the oil implicated as the cause of the 1981 outbreak of Toxic Oil Syndrome (TOS) in Spain, may have been responsible for the unusual symptomatology characterizing this disease. The essential features of TOS were peripheral eosinophilia, pulmonary oedema and endothelial damage in the acute phase; myalgia, sensory neuropathy, hepatic injury, skin oedema and sicca in the intermediate phase; and peripheral neuropathy, muscle wasting, scleroderma and hepatopathy in the chronic phase. Of the more than 70 chemical entities and mixtures reviewed here, none had been reported as producing adverse toxic effects upon ingestion resembling the specific set of symptoms and progression that characterized TOS. Because of their viscosity, the most commonly recorded disease process associated with oral ingestion of petroleum refinery products was lipid pneumonia, implicating lung exposure via aspiration. The mineral oil additives and contaminants comprised a highly diverse range of chemical entities, producing a variety of symptoms in instances of poisoning. Specifically, no chemical entity amongst the refinery products, additives or contaminants was described as inducing a syndrome involving vasculitis accompanied by thrombotic events, along with immunological consequences (such as T-lymphocyte activation and cytokine release), as is considered to be the cellular basis of TOS.

Oleogranulomatous response in lymph nodes associated with emollient use in Netherton's syndrome

Paraffin-based emollients are widely used in dermatological practice and are not usually absorbed through the skin. We report a case where transcutaneous transfer did occur in the context of damaged skin in Netherton's syndrome, resulting in a reversible lymphadenopathy.