Toxicity of Coumaphos Residues in Beeswax Foundation to the Honey Bee Brood.

Coumaphos is one of the most frequently detected pesticides in recycled beeswax. The objective was to assess the maximal level of coumaphos in foundation sheets that could exist without lethal effects on the honey bee larvae. Brood development was followed in cells drawn on foundation squares containing coumaphos ranging from 0 to 132 mg/kg. Furthermore, larval exposure was determined by measuring the coumaphos level in the drawn cells. Coumaphos levels in the initial foundation sheets up to 62 mg/kg did not increase brood mortality because the emergence rates of bees raised on these foundation squares were similar to controls (median of 51%). After a single brood cycle, coumaphos levels in the drawn cells were up to three times lower than the initial levels in foundation sheets. Hence, coumaphos levels of 62 mg/kg in the initial foundation sheets, almost the highest exposures, resulted in levels of 21 mg/kg in drawn cells. A significantly reduced emergence rate (median of 14%) was observed for bees raised on foundation sheets with initial coumaphos levels of 132 mg/kg, indicating increased brood mortality. Such levels resulted in coumaphos concentrations of 51 mg/kg in drawn cells, which is close to the median lethal concentration (LC50) as determined in previous in vitro experiments. In conclusion, brood mortality was increased on wax foundation sheets with initial coumaphos levels of 132 mg/kg, while no elevated mortality was observed for levels up to 62 mg/kg. Environ Toxicol Chem 2023;42:1816-1822. © 2023 The Authors. Environmental Toxicology and Chemistry published by Wiley Periodicals LLC on behalf of SETAC.

Waxing activity as a potential source of exposure to per- and polyfluoroalkyl substances (PFAS) and other environmental contaminants among the US ski and snowboard community.

BACKGROUND: Skiers and snowboarders apply waxes and solvents to their equipment to enhance glide across the snow. Waxing results in exposures to per- and polyfluoroalkyl substances (PFAS) and particulate matter, which have been associated with adverse health effects among professional wax technicians in Scandinavia. However, little is known about exposure among people who participate at other levels of sport, including recreationally, in other regions. OBJECTIVE: We sought to characterize wax-related exposures among US skiers and snowboarders who participate across numerous levels of sport to expand scientific understanding of environmental health risks among this population. METHODS: We used an anonymous electronic survey to evaluate wax-related exposures among US cross-country and downhill skiers and snowboarders. Specifically, we assessed (Fang et al., 2020): duration of time involved with each sport in any role (Freberg et al., 2013), intensity of wax-related exposures based on time spent in waxing areas, wax use, and wax type (Rogowski et al., 2007), frequency of fluorinated wax application, and (Freberg et al., 2010) use of exposure interventions. RESULTS: Participants tended to be long-term winter sports enthusiasts (e.g., median downhill skiing duration: 31 years). Nearly all (92%) participants personally applied some wax to their skis/snowboards and most applied waxes containing PFAS (67%) and solvents (62%). Ski professionals waxed the most pairs of skis with fluorinated waxes annually (median (IQR): 20 (1, 100)), though individuals participating recreationally also applied fluorinated waxes regularly. Exposure interventions were not widely used. SIGNIFICANCE: Waxing activities may pose significant risk of exposure to PFAS and other environmental contaminants among the US ski and snowboard community. Efforts are needed to reduce these exposures through changes to wax use patterns and broader adoption of exposure reduction strategies.

An in vitro model for assessing the toxicity of pesticides in beeswax on honey bee larvae.

While many studies have examined residue levels in beeswax, little is known about the levels that pose a risk for honey bee development. In an in vitro study, we aimed to assess the toxicity of pesticides in wax for worker larvae using coumaphos as a model substance. First, we reared larvae in beeswax with the aim to correlate the larval toxicity to the corresponding levels of coumaphos in beeswax. In a second step, we tested to which extent coumaphos migrates from the beeswax into the larval diet and if such dietary levels are toxic to larvae. We observed dose-related toxicity when larvae were exposed to coumaphos concentrations in beeswax from 30 to 100 mg/kg. The lethal concentration in 50% of the individuals (LC50) was calculated to be 55.9 mg/kg, while the no observed effect concentration (NOEC) for exposure of larvae to coumaphos in wax was 20 mg/kg. Additional test series without larvae allowed to assess the migration of coumaphos from the beeswax into the diet. The resulting dietary coumaphos concentrations were four to five times lower than the initial concentrations in wax. In accordance, the LC50 for chronic exposure of larvae to coumaphos in the diet was 12.5 mg/kg, which was 4.5 times lower than the LC50 obtained for wax exposure. Finally, a coumaphos level of 20 mg/kg in wax led to a dietary concentration of 3.9 mg/kg that was close to the NOEC of 3 mg/kg obtained in the diet. In conclusion, both experimental approaches suggest that coumaphos concentrations of up to 20 mg/kg in wax are non-lethal.

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.

Honey bee queen health is unaffected by contact exposure to pesticides commonly found in beeswax.

Honey bee queen health is crucial for colony health and productivity, and pesticides have been previously associated with queen loss and premature supersedure. Prior research has investigated the effects of indirect pesticide exposure on queens via workers, as well as direct effects on queens during development. However, as adults, queens are in constant contact with wax as they walk on comb and lay eggs; therefore, direct pesticide contact with adult queens is a relevant but seldom investigated exposure route. Here, we conducted laboratory and field experiments to investigate the impacts of topical pesticide exposure on adult queens. We tested six pesticides commonly found in wax: coumaphos, tau-fluvalinate, atrazine, 2,4-DMPF, chlorpyriphos, chlorothalonil, and a cocktail of all six, each administered at 1, 4, 8, 16, and 32 times the concentrations typically found in wax. We found no effect of any treatment on queen mass, sperm viability, or fat body protein expression. In a field trial testing queen topical exposure of a pesticide cocktail, we found no impact on egg-laying pattern, queen mass, emergence mass of daughter workers, and no proteins in the spermathecal fluid were differentially expressed. These experiments consistently show that pesticides commonly found in wax have no direct impact on queen performance, reproduction, or quality metrics at the doses tested. We suggest that previously reported associations between high levels of pesticide residues in wax and queen failure are most likely driven by indirect effects of worker exposure (either through wax or other hive products) on queen care or queen perception.

Effects of developmental exposure to pesticides in wax and pollen on honey bee (Apis mellifera) queen reproductive phenotypes.

Stressful conditions during development can have sub-lethal consequences on organisms aside from mortality. Using previously reported in-hive residues from commercial colonies, we examined how multi-pesticide exposure can influence honey bee (Apis mellifera) queen health. We reared queens in beeswax cups with or without a pesticide treatment within colonies exposed to treated or untreated pollen supplement. Following rearing, queens were open-mated and then placed into standard hive equipment in an "artificial swarm" to measure subsequent colony growth. Our treated wax had a pesticide Hazard Quotient comparable to the average in beeswax from commercial colonies, and it had no measurable effects on queen phenotype. Conversely, colonies exposed to pesticide-treated pollen had a reduced capacity for viable queen production, and among surviving queens from these colonies we observed lower sperm viability. We found no difference in queen mating number across treatments. Moreover, we measured lower brood viability in colonies later established by queens reared in treated-pollen colonies. Interestingly, royal jelly from colonies exposed to treated pollen contained negligible pesticide residues, suggesting the indirect social consequences of colony-level pesticide exposure on queen quality. These findings highlight how conditions during developmental can impact queens long into adulthood, and that colony-level pesticide exposure may do so indirectly.

Comparison of bone wax and chitosan usage on post-sternotomy bone healing.

BACKGROUND: Sternotomy is a standard approach performed in almost every surgical procedure on the heart and mediastinum. Effective hemostasis of the sternum is required to keep the operative field dry, avoid excessive blood transfusions during surgery, and prevent reoperation due to massive postoperative bleeding, which can further increase morbidity and mortality in patients. Bone wax is a mechanical hemostat commonly used after sternotomy and has been known to affect bone healing, trigger chronic inflammatory reactions, and increase the rate of infection. The application of chitosan, which has intrinsic hemostat ability, as hemostatic material is believed to improve bone healing following sternotomy. This study aimed to compare the effectiveness of bone wax and chitosan on bone healing after sternotomy. METHODS: Median sternotomies were performed on 2 groups of New Zealand White rabbits. Each group of 16 animals received either bone wax or chitosan powder as hemostatic material. The degree of bone healing, the number of foreign-body giant cells, and the number of osteoblasts were evaluated after 6 weeks. RESULTS: Radiographs showed that significantly more animals in the chitosan group had total sternal healing (p = 0.033). Histopathology revealed that the number of foreign-body giant cells was significantly less (p = 0.036) and the number of osteoblasts was significantly greater (p < 0.0001) in the group of animals that received chitosan. CONCLUSION: The use of chitosan as hemostatic material can promote better bone healing compared to bone wax.

Mineral oils and waxes in cosmetics: an overview mainly based on the current European regulations and the safety profile of these compounds.

Mineral oils and waxes are mixtures of predominantly saturated hydrocarbons consisting of straight-chain, branched and ring structures with carbon chain lengths greater than C14. They have been used for many decades in skin and lip care cosmetic products due to their excellent skin tolerance as well as their high protecting and cleansing performance and broad viscosity options. In contrast to vegetable oils, mineral oils are non-allergenic since they are highly stable and not susceptible to oxidation or rancidity. They have a long history of safe use which is confirmed by clinical and epidemiological data. In Europe, mineral oils are only permitted in cosmetics if compliant with purity specifications on polycyclic aromatic hydrocarbons and safety requirements laid down in the European pharmacopoeia and the EU cosmetics regulation EC/1223/2009. The high quality of these mineral oils is assured by robust quality assurance and a refining/purification process designed to exclude substances with carcinogenic potential and to minimize the presence of mineral oil aromatic hydrocarbons. Given their highly lipophilic properties, mineral oils do not penetrate human skin and, thus, are not systemically bioavailable in the body. Moreover, no significant changes in the skin and no effects on any internal organ system have been reported and attributed to the topical application of refined mineral oils. Regarding potential oral exposure from cosmetic lip care products, Cosmetics Europe, the European trade association for the cosmetics and personal care industry, has advised cosmetic manufacturers to only use mineral oil fractions for which recognized food acceptable daily intake (ADI) values apply. The estimated dose of mineral oils ingested via lip care products contributes to <10% of the ADI value and should therefore be considered of no toxicological concern.

Scented Candles as an Unrecognized Factor that Increases the Risk of Bladder Cancer; Is There Enough Evidence to Raise a Red Flag?

The causes of bladder cancer are not yet fully uncovered, however the research has identified a number of factors that may increase the risk of developing this cancer. The chemical carcinogenesis of bladder cancer due to chronic exposure to aromatic hydrocarbons has been well-established. The identification of this correlation led to an improvement of safety measures in chemical industry and a gradual decrease of bladder cancer cases among workers. Nevertheless, in the majority of bladder cancer cases, the specific cause of the disease still can't be specified. It makes the question of unrecognized factors associated with bladder cancer development even more relevant. Taking under consideration known chemical carcinogenesis of bladder cancer, this minireview takes under investigation the possible link between using scented candles and a risk of bladder cancer development. Burning scented candles contain many of the substances that are associated with a bladder cancer. Furthermore the scented candles are not only very popular but also widely available on the market, with limited quality regulations and unspecified raw materials determining a spectrum of potentially dangerous substances emitted during burning.

An appraisal of cuticular wax of Calotropis procera (Ait.) R. Br.: Extraction, chemical composition, biosafety and application.

Plastic and polythene as hydrophobic materials become a grave concern due to their non-biodegradable nature, cumbersome recycling and waste management. Cuticular wax derived from Calotropis procera is explored as an eco-friendly and safe hydrophobic material. The effects of duration of exposure to solvent, solvent type, size and side of the leaf on cuticular wax yield have been studied. Leaf with the smallest area (10 cm2-25 cm2) was found to be the most suitable to isolate the wax. GC-MS analysis of the wax revealed that the wax consists of mainly esters, alkane and alkene. Mitochondrial reductase (MTT) and lactate dehydrogenase (LDH) assay have been carried out on M5S cell line at various concentrations and the results indicate that up to 1 µg/ml (acetone as solvent) and 3 µg/ml (chloroform as solvent) use of wax has no toxic effect. To evaluate the hydrophobic potential of the wax in developing hydrophobic paper water regains and contact angle has been measured. The gain in hydrophobicity of the paper is evident from the rise in contact angle (≥90˚) of paper coated with wax. Scanning electron micrograph and FTIR spectra generated physical and chemical evidence of coating of wax on paper.

Review of data on the dermal penetration of mineral oils and waxes used in cosmetic applications.

Mineral oils and waxes used in cosmetic products, also referred to as "personal care products" outside the European Union, are mixtures of predominantly saturated hydrocarbons consisting of straight-chain, branched and ring structures with carbon chain lengths greater than C16. They are used in skin and lip care cosmetic products due to their excellent skin tolerance as well as their high protecting and cleansing performance and broad viscosity options. Recently, concerns have been raised regarding potential adverse health effects of mineral oils and waxes from dermal application of cosmetics. In order to be able to assess the risk for the consumer the dermal penetration potential of these ingredients has to be evaluated. The scope and objective of this review are to identify and summarize publicly available literature on the dermal penetration of mineral oils and waxes as used in cosmetic products. For this purpose, a comprehensive literature search was conducted. A total of 13 in vivo (human, animal) and in vitro studies investigating the dermal penetration of mineral oils and waxes has been identified and analysed. The majority of the substances were dermally adsorbed to the stratum corneum and only a minor fraction reached deeper skin layers. Overall, there is no evidence from the various studies that mineral oils and waxes are percutaneously absorbed and become systemically available. Thus, given the absence of dermal uptake, mineral oils and waxes as used in cosmetic products do not present a risk to the health of the consumer.

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.

Safety assessment of stearyl heptanoate and related stearyl alkanoates as used in cosmetics.

Stearyl heptanoate is an ester of stearyl alcohol and heptanoic acid that functions in cosmetics as a skin conditioning agent and is in the general class of chemicals called stearyl alkanoates. Stearyl caprylate, stearyl palmitate, stearyl stearate, stearyl behenate, and stearyl olivate are stearyl alkanoates with similar chemical structures, toxicokinetics, and functions in cosmetics. These water-insoluble stearyl alkanoates, when metabolized, yield stearyl alcohol and a corresponding fatty acid. The available information supports the safety of all of the related stearyl alkanoates. The Expert Panel concluded that stearyl heptanoate, stearyl caprylate, stearyl palmitate, stearyl stearate, stearyl behenate, and stearyl olivate are safe in the present practices of use and concentration.

Wound healing properties of jojoba liquid wax: an in vitro study.

AIM OF THE STUDY: The wound healing properties of jojoba (Simmondsia chinensis) liquid wax (JLW) were studied in vitro on HaCaT keratinocytes and human dermal fibroblasts, which are involved in wounded skin repair. MATERIALS AND METHODS: JLW cytotoxicity was evaluated by the crystal violet staining and the neutral red uptake endpoint. Induction of wound healing by JLW was assessed by scratch wound assay on cell monolayers. The involvement of signaling pathways was evaluated by the use of the Ca(2+) chelator BAPTA and of kinase inhibitors, and by Western blot analysis of cell lysates using anti-phospho antibodies. Collagen and gelatinase secretion by cells were assayed by in-cell ELISA and zymography analysis, respectively. RESULTS: Cytotoxicity assays showed that the toxic effects of JLW to these cells are extremely low. Scratch wound experiments showed that JLW notably accelerates the wound closure of both keratinocytes and fibroblasts. The use of inhibitors and Western blot revealed that the mechanism of action of JLW is strictly Ca(2+) dependent and requires the involvement of the PI3K-Akt-mTOR pathway and of the p38 and ERK1/2 MAPKs. In addition, JLW was found to stimulate collagen I synthesis in fibroblasts, while no effect was detected on the secretion of MMP-2 and MMP-9 gelatinases by HaCaT or fibroblasts. CONCLUSIONS: Taken together, data provide a pharmacological characterization of JLW properties on skin cells and suggest that it could be used in the treatment of wounds in clinical settings.

Fish-induced keriorrhea.

Many deep-sea fishes store large amounts of wax esters in their body for buoyancy control. Some of them are frequently caught as by-catch of tuna and other fishes. The most noteworthy ones include escolar and oilfish. The accumulation of the indigestible wax esters in the rectum through consumption of these fish engenders discharges or leakage per rectum as orange or brownish green oil, but without noticeable loss of water. This physiological response is called keriorrhea, which is variously described as "oily diarrhea," "oily orange diarrhea," or "orange oily leakage" by the mass media and bloggers on the internet. Outbreaks of keriorrhea have been repeatedly reported across continents. Additional symptoms including nausea, vomiting, abdominal cramps, and diarrhea were complained by the victims. They are probably due to anxiety or panic when suffering from keriorrhea. Escolar and oilfish are banned from import and sale in Italy, Japan, and South Korea. Rapid detection of the two fishes is imperative to ensure proper labeling and safeguarding of the public before and after any keriorrhea outbreak.

Induction of multiple granulomas in the liver with severe hepatocyte damage by montan wax, a natural food additive, in a 90-day toxicity study in F344 rats.

Montan wax is a mineral wax extracted from lignite type coal. It has been registered as a food additive in Japan though there have been no reports of toxicological evaluation, mainly due to the fact that it is considered a natural product. As part of a general safety assessment of montan wax, we have performed a 90-day toxicity study in Fisher 344 (F344) rats. Groups of 10 males and 10 females were given the material at dose levels of 0 (Group 1), 0.56 (Group 2), 1.67 (Group 3), or 5% (Group 4) in the diet for 90 days. During the experiment, there were no remarkable changes in general conditions and no deaths occurred in any group. On hematological examination, Hb, Ht, MCV and MCH were significantly decreased and WBC was significantly increased in all treated rats. On serum biochemical examination, AST and ALT were found to be elevated more than four fold in all treated groups as compared to the respective control group values in both sexes. Furthermore, relative organ weights for the liver, spleen, lung and kidneys were increased in all treated groups of both sexes. Histopathological examination revealed diffuse multiple granulomas in the livers with severe hepatocyte damage and lymphocytic infiltration. Granulomatous lesions were also apparent in the mesenteric lymph nodes in all treated males and females. These findings clearly demonstrate that montan wax, at doses of more than 0.56% in the diet, induces multiple granulomas with severe inflammation in the liver. Because pathological, hematological and serum biochemical changes were observed in the lowest dose group, a no-observed-adverse-effect level (NOAEL) could not be determined in the present study.

Mutagenic activity of sweepings and pigments from a household-wax factory assayed with Salmonella typhimurium.

The mutagenic activity of garbage originating from a household wax industry was determined by the Salmonella/microsome assay, using the bacterial strains TA100, TA98 and YG1024. The garbage was obtained by sweeping the floor of the factory at the end of the work shift. Organic compounds were extracted by ultrasound for 30 min in dichloromethane or 70% ethanol. After evaporation of solvent, these extracts (HFS: household-wax factory sweepings) were dissolved in DMSO, and were tested for the mutagenic activity at varying concentrations (HFS-ET: 0.08-0.68 mg/plate, HFS-DCM: 0.60-7.31 mg/plate). The colouring agents (pigments) used in the production of the wax were also dissolved in DMSO and tested with the assay. The concentrations tested for each pigment were: Amaranth: 0.46-3.65 mg/plate, Auramine: 0.15-1.2 mg/plate and Rhodamine B: 0.22-1.82 mg/plate. Both ET and DCM organic extracts had mutagenic activity, especially in the YG1024 strain. The pigments behaved in a similar way, demonstrating that YG1024 was the most sensitive strain for the detection of mutagenicity, and that metabolization increased the activity. Human exposure (occupational and non-occupational) to industrial residues generated during the household-wax manufacturing and packaging process should be monitored, since this type of garbage is normally deposited in the environment without any control.

Pressurization of vertebral bodies during vertebroplasty causes cardiovascular complications: an experimental study in sheep.

STUDY DESIGN: An experimental study of cardiovascular complications arising during vertebroplasty (VP) of multiple levels in sheep. OBJECTIVES: To investigate the effect of pressurizing vertebral bodies during VP using different materials in the development of fat embolism (FE) and any associated cardiovascular changes. SUMMARY OF BACKGROUND DATA: Polymethylmethacrylate (PMMA) is the material of choice for VP. However, PMMA has several disadvantages, such as toxicity, exothermic curing, uncertain long-term biomechanical effects, and biocompatibility. Alternative materials are being developed for VP; however, there is the concern that an increase in intraosseous pressure and displacement of bone marrow contents could lead to FE and hypotension during VP regardless of what type of materials is used. METHODS: In 20 sheep, four vertebral bodies were augmented either with PMMA or bone wax. Heart rate; arterial, central venous, and pulmonary artery pressure; cardiac output; and blood gas values were recorded. Postmortem the lungs were subjected to histologic evaluation. RESULTS: The consecutive augmentation of four vertebral bodies with PMMA induced a cumulative FE that gradually deteriorated baseline mean arterial blood pressure (MABP) and blood gas values. The augmentation with bone wax resulted in similar cardiovascular changes and amount of intravascular fat in the lungs. CONCLUSION: There are potential cardiovascular complications during VP of multiple levels regardless of the augmentation material used. The deteriorating baseline MABP during VP is associated with the pressurization of the vertebral bodies rather than with the use of polymethylmethacrylate.

A study of the toxicity of five mineral hydrocarbon waxes and oils in the F344 rat, with histological examination and tissue-specific chemical characterisation of accumulated hydrocarbon material.

Five food-grade mineral hydrocarbon (MHC) materials; a low melting point wax (LMPW), a synthetic wax (C80W) and three white oils (N15H, N70H and P70H) were administered orally to female Fischer-344 rats for 28 and 90 days at a dose level of 2% in the diet. Tissues were examined at autopsy for any treatment-related histopathological changes. The histology of target organs was the same as found in previous studies on LMPW and mineral oils and similar effects were also observed from feeding C80W. Chemical analysis showed no detectable levels of MHCs in urine and no discernible differences in the MHC profile in faeces extracts compared to diets. The presence of MHCs in most tissues was not always associated with observable histological changes. The notable observations were MHC material was detected in all tissues of rats fed with diets containing LMPW and C80W. The levels found ranged from 0.04 to 1.52% by weight for the LMPW and from 0.01 to 0.75% for the C80W. MHC material was detected in all samples of small intestine, heart and kidney for all groups. Only the livers from rats administered with LMPW and C80W were analysed, which were found to contain MHC material. Preferential accumulation of MHCs was in the alkane range approximately C(20)-C(35). The findings indicate that the size and the structure of individual components play a role both in determining their propensity to accumulate in different tissues and in the severity of any response that they elicit once they have accumulated. The implication of these findings are discussed in the context of specifications for 'food-grade' mineral hydrocarbons such as used as food additives. The data presented here suggests that the current specifications are not prescriptively adequate in controlling the amount of MHC material between C(25) and C(35) that can accumulate.

Effects of current and potential dental etchants on nerve compound action potentials.

In this study, a 35% phosphoric acid gel (3M Scotchbond etchant), a nonrinse etchant (NRC), and two EDTA-containing conditioners (RC-Prep and File-Eze) were tested in vitro for blocking nerve conductance evoked in the rat sciatic nerve after local application. The phosphoric acid gel and NRC completely and irreversibly inhibited conductance. On the other hand, RC-Prep reduced the compound action potentials (cAPs) by 50% in 120 min. With File-Eze, the reduction in cAPs was less than 50% after an application time of 160 min (61.8 +/- 1.8%). At 160 min the cAPs in the RC-Prep group had been inhibited by 62.4%. These results indicated strong neurotoxic effects of phosphoric acid and NRC when applied directly on exposed pulp in the total etch procedure.