Abstract  Dipropylene glycol (DG) has been considered safe to use as a solvent in perfumes and other cosmetics (1). Our recent case of allergic contact dermatitis from DG in a hand lotion (2) prompted this further study. Materials and Methods: We used standard (S) DG (synthesis grade purity >97%) from E. Merck (Darmstadt, Germany) and cosmetic grade (CG) DG (purity 96%) from our case (2). In a pilot study, 34 eczema patients were patch tested with either S or CG DG at 10%, 5%, 2% and 1% aq. When no reactions were seen, the standard series at Gentofte was supplemented with DG 10% aq., S and CG, for 7 months (25.1.94- 25.8.94). 503 consecutive eczema patients, 212 men and 291 women, were tested, patches being applied for 2 days, using Scanpor tape and Finn Chambers, and reactions being read at D2, D3 and 05-7. The original patient (2) was repatch tested with both S and CG DG at I% and 0.5% aq. Results: 6. 7% (34/503) of the patients reacted to at least 1 of S and CG DG (Table 1). There was l positive patch test reaction to S DG, the remaining reactions being either ?+, 5.1% (26/503), or IR, 1.4% (7/503) (no sex difference). 10 of those with ?+ reactions to DG were also tested with their own cosmetics and 2 reacted, l to mascara, skin tonic and eye shadow, and I to camomile liniment (DG contents not determined). The original patient (2) had + + and + + + reactions to CG DG, as well as to S DG, 0.5% and 1% aq. Discussion: DG is a mixture of 3 isomers (1), their distribution in the 2 grades used in this study differing as determined by GC/MS (2). The original patient (2) reacted to both grades and no difference was found between the frequency of reactions to the 2 grades in 503 consecutive eczema patients. Only 1 patient out of 503 (0.2%), however, had a definitely positive patch test reaction to DG, its clinical relevance not being established. Patch testing with other grades of DG used in cosmetics (I) might give different results, but at present, we consider contact allergy to dipropylene glycol to be rare in our study population.

Abstract  Toxline abstract: Technical rept. 19 Jun-12 Sep 90. See also Laboratory Supplement, PB92-196187. Sponsored by National Toxicology Program, Research Triangle Park, NC. Dipropylene glycol (DPG) is a high production glycol used in the manufacture of nitrocellulose solvent, lacquers, paints, printing inks, and shellac varnishes. In general, the toxicity of the glycols decreases as the molecular weight of the molecule increases. Therefore, it could be predicted that DPG would be less toxic than low molecular weight glycols such as ethylene glycol. Since, there is a lack of data with which to confirm this hypothesis this study was conducted to assess the potential for DPG to cause developmental toxicity and to compare its toxicity to other glycols. DPG (CAS No. 25265-71-8) was administered by gavage to timed-pregnant CD and Ntilde; rats (20-25/group) on gestational days (GD) 6-15 at dose levels of 0, 800, 2,000, or 5,000 mg/kg body weight/day. Animals were observed daily for clinical signs of toxicity. Food and water weights and body weights were reported on GD 0, 3, 6, 9, 12, 15, 18, and 20. All animals were killed on GD 20 and examined for maternal body and organ weights, implant status, fetal weight, sex, and morphological development. The mid-dose (2,000 mg/kg/day DPG) produced maternal lethality in 1 out of 25 pregnant animals while the high dose (5,000 mg/kg/day) caused the death of 2 out of 22 pregnant animals. Maternal body weights were significantly decreased in the 5,000 mg/kg/day group from GD 9 through GD 20. Maternal body weight gain of the animals exposed to 5,000 mg/kg/day was significantly reduced across the treatment period and across gestation. Corrected maternal weight gain (gestation gain minus gravid uterine weight) was also significantly reduced in the 5,000 mg/kg/day group. Absolute (g/day) and relative (g/kg body weight/day) food consumption of animals in the 5,000 mg/kg/day group were significantly decreased from control for the intervals from GD 6 to 9 and GD 9 to 12. As a result, the absolute and relative food consumption was decreased during treatment (GD 6 to 15) and across gestation (GD 0 to 20). Absolute food consumption was decreased in the animals from the 2,000 mg/kg/day group from GD 6 to 9. Relative water consumption by the animals in the 5,000 mg/kg/day group was increased for all measurement periods between GD 9 and GD 18. Relative liver weight of the maternal animals was significantly increased in the animals exposed to 2,000 and 5,000 mg/kg/day of DPG. No effects of DPG were observed on pre- or post-implantation loss. The mean male and female body weights per litter were associated with a significant decreasing linear trend, but mean male and female body weights were not significantly different from control in the exposed groups. Examination of the fetuses for external, visceral and skeletal malformations and variations did not reveal any significant effects among dose groups. In summary, there was no maternal or developmental toxicity at 800 mg/kg/day of DPG. Maternal toxicity and lethality were observed at 2,000 and 5,000 mg/kg/day, but developmental toxicity was not observed even at these maternally lethal exposures.

Abstract  In a prior study on electronic cigarette (EC) refill fluids, Cinnamon Ceylon was the most cytotoxic of 36 products tested. The purpose of the current study was to determine if high cytotoxicity is a general feature of cinnamon-flavored EC refill fluids and to identify the toxicant(s) in Cinnamon Ceylon. Eight cinnamon-flavored refill fluids, which were screened using the MTT assay, varied in their cytotoxicity with most being cytotoxic. Human embryonic stem cells were generally more sensitive than human adult pulmonary fibroblasts. Most products were highly volatile and produced vapors that impaired survival of cells in adjacent wells. Cinnamaldehyde (CAD), 2-methoxycinnamaldehyde (2MOCA), dipropylene glycol, and vanillin were identified in the cinnamon-flavored refill fluids using gas chromatography–mass spectrometry and high-pressure liquid chromatography (HPLC). When authentic standards of each chemical were tested using the MTT assay, only CAD and 2MOCA were highly cytotoxic. The amount of each chemical in the refill fluids was quantified using HPLC, and cytotoxicity correlated with the amount of CAD/product. Duplicate bottles of the same product were similar, but varied in their concentrations of 2MOCA. These data show that the cinnamon flavorings in refill fluids are linked to cytotoxicity, which could adversely affect EC users.