Peroxisome proliferator di-isodecyl phthalate has no carcinogenic potential in Fischer 344 rats

Association of Exposure to Di-2-Ethylhexylphthalate Replacements With Increased Insulin Resistance in Adolescents From NHANES 2009-2012

CONTEXT

Di-isononyl phthalate (DINP) and di-isodecyl phthalate (DIDP) are environmental chemicals increasingly used to replace di-2-ethylhexylphthalate (DEHP) and commonly found in processed foods. Phthalate exposures, in particular DEHP, have been associated with insulin resistance in adolescents, but there are no data regarding the two substitutes, DINP and DIDP.

OBJECTIVE

This study aimed to examine associations of DINP, DIDP, and DEHP with insulin resistance outcomes.

DESIGN, SETTING, AND PARTICIPANTS

This was a cross-sectional analysis of 2009-2012 National Health and Nutrition Examination Surveys (NHANES) composed of 356 fasting 12-19-year-olds.

MAIN OUTCOME MEASURES

Insulin resistance as a categorical outcome expressed as homeostatic model assessment of insulin resistance (HOMA-IR), using a cut point of 4.39 to define insulin resistance. We also examined continuous HOMA-IR as an outcome in secondary analyses.

RESULTS

Controlling for demographic and behavioral factors, diet, age, body mass index, and urinary creatinine, for each log increase in DINP metabolite, a 0.08 (P = .001) increase in HOMA-IR was identified. Compared with the first tertile of DINP (23.4% adjusted prevalence), the third tertile was associated with a 34.4% prevalence (95% confidence interval [CI], 27.3-41.6%; P = .033) of insulin resistance. Similarly, compared with the first tertile of DEHP (20.5% adjusted prevalence), the third tertile had 37.7% prevalence (95% CI 29.8-45.6%; P = .003).

CONCLUSIONS

Urinary DINP concentrations were associated with increased insulin resistance in this cross-sectional study of adolescents. The previously identified association of DEHP with insulin resistance was also confirmed. Further, longitudinal studies are needed to confirm these associations, with the possibility to assess opportunities for intervention.

Spontaneous multicentric malignant schwannoma in a male Fischer 344 rat

We describe here a multicentric spontaneous malignant schwannoma obtained from one male F344 rat, and this animal was the subject of a carcinogenicity study for which it was treated with diisodecyl phthalate. The animal of the control group not treated with diisodecyl phthalate showed dyspnea and severe lordosis. On the necropsy, two tan, firm, encapsulated masses were observed in the subcutis of the lumbosacral region and the left inguinal region of the abdominal cavity, respectively; the masses were 25 × 17 × 8 mm and 16 × 14 × 8 mm in size, respectively. Histologically, the tumor consisted of spindle and pleomorphic cells that grew in various patterns, that was, sweeping fascicles and herringbone and local organoid patterns. The pleomorphic neoplastic cells had more than two nuclei. Additionally, the diagnosis of malignant schwannoma was confirmed by the immune reactivity of the tumor cells for S-100 protein.

Urinary biomarkers for phthalates associated with asthma in Norwegian children

BACKGROUND

High-molecular-weight phthalates in indoor dust have been associated with asthma in children, but few studies have evaluated phthalate biomarkers in association with respiratory outcomes.

OBJECTIVES

We explored the association between urinary concentrations of phthalate metabolites and current asthma.

METHODS

In a cross-sectional analysis, 11 metabolites of 8 phthalates [including four metabolites of di(2-ethylhexyl) phthalate] were measured in one first morning void collected from 2001 through 2004 from 623 10-year-old Norwegian children. Logistic regression models controlling for urine specific gravity, sex, parental asthma, and income were used to estimate associations between current asthma and phthalate metabolite concentrations by quartiles or as log10-transformed variables.

RESULTS

Current asthma was associated with both mono(carboxyoctyl) phthalate (MCOP) and mono(carboxynonyl) phthalate (MCNP), although the association was limited to those in the highest quartile of these chemicals. The adjusted odds ratio (aOR) for current asthma was 1.9 (95% CI: 1.0, 3.3) for the highest MCOP quartile compared with the lowest quartile, and 1.3 (95% CI: 0.98, 1.7) for an interquartile-range increase. The aOR for current asthma was 2.2 (95% CI: 1.2, 4.0) for the highest MCNP quartile and 1.3 (95% CI: 1.0, 1.7) for an interquartile-range increase. The other phthalate metabolites were not associated with current asthma.

CONCLUSIONS

Current asthma was associated with the highest quartiles of MCOP and MCNP, metabolites of two high molecular weight phthalates, diisononyl phthalate and diisodecyl phthalate, respectively. Given the short biological half-life of the phthalates and the cross-sectional design, our findings should be interpreted cautiously.

Biodegradation of diisodecyl phthalate (DIDP) by Bacillus sp. SB-007

In this study, diisodecyl phthalate (DIDP) was efficiently degraded by Bacillus sp. SB-007. The optimal conditions for DIDP (100 mg l(-1)) degradation by Bacillus sp. SB-007 in a mineral salts medium were found to be pH 7.0 at 30 degrees C, stirring at 200 rpm. The specific rate of DIDP degradation was found to be concentration dependent with a maximum of 4.87 mg DIDP l(-1) h(-1). DIDP was transformed rapidly by Bacillus sp. SB-007 with the formation of monoisodecyl phthalate and phthalic acid, which subsequently degraded further. These results highlight the potential of this bacterium for removing DIDP contaminated waste in the environment.