Seeking solutions to chemical mixtures challenges in public health

Mumtaz, M.M.; Rosa, Christopher T. De; Cibulas, William; Falk, Henry

doi:10.1016/j.etap.2004.06.006

Cited by 7 publications

(4 citation statements)

References 23 publications

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“…It is noteworthy that the health effects that are common to the BTEX compounds are of neurological nature (Mumtaz et al 2004;Robinson, Mc Donell 2004;Pohl et al 2003). Benzene has hematological effect and is classified in EPA Group A (human carcinogen).…”

Section: Resultsmentioning

confidence: 99%

Determination of Oil and Grease, Total Petroleum Hydrocarbons and Volatile Aromatic Compounds in Soil and Sediment Samples

Rauckyte

Żak

Pawlak³

et al. 2010

Journal of Environmental Engineering and Landscape Management

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This paper describes a case study of petroleum‐contaminated soil/sediment samples which were analyzed using gas chromatography‐flame ionization detector (GC‐FID) for total petroleum hydrocarbons (TPH), volatile aromatic com‐pounds: benzene, toluene, ethylbenzene, and xylenes (BTEX) and naphthalene by GC‐MS, and oil and grease (O/G) con‐tent by sonication in hexane. The ratio of (TPH) / (O/G) shows that the hydrocarbon fraction is between 7% and 87%. The content of volatile organic fraction BTEX accounts for only a small proportion of total TPH, and the ratio of (BTEX) / (TPH) ranges from 0.1% to 0.6%. It should be stressed that the use of TPH methods as against gas chromatography must be done with care because the potential risk posed by BTEX compounds may not be adequately addressed. Santrauka Aprašomi nafta užterštu dirvožemio bei dumblo pavyzdžiai, kuriuose duju chromatografijos būdu GC‐FIDnustatytas bendrasis naftos angliavandeniliu kiekis (TPH), o GC‐MS – lakieji aromatiniai junginiai: benzenas, toluenas, etilbenzenas ir ksilenai (BTEX) bei naftalenas. Sonifikacijos n‐heksane būdu nustatytas alieju ir riebalu (O/G) kiekis. TPH ir O/G santykis rodo, kad angliavandeniliu frakcijos yra nuo 7% iki 87%. Lakioji organine frakcija (BTEX) sudaro palyginti maža bendrojo naftos angliavandeniliu kiekio (TPH) dali, o BTEX ir TPH santykis svyruoja nuo 0,1% iki 0,6%. Ypač vertetu atkreipti demesi i bendrojo naftos angliavandeniliu kiekio (TPH) nustatyma duju chromatografijos būdu, nes galimas lakiosios organines frakcijos (BTEX) pavojingumas gali būti nepakankamai ivertintas. Peзюме Описаны образцы почвы и седимента, в которых способом хроматографии газа GC-FID определено общее количество нефтяных углеводородов (TPH), при помощи GC-MS установлены летучие ароматические соединения: бензол, толуол, этилобензол, ксилолы (BTEX) и нафталин. Способом сонификации в н-гексане определено количество масел и жиров (O/G). Отношение (TPH) / (O/G) свидетельствует о том, что в них содержится от 7% до 87% фракции углеводородов. Летучие ароматические соединения составляют относительно небольшую часть cyммарных нефтяных углеводородов, а отношение (BTEX) / (TPH) колеблется в пределах 0,1–0,6%. Особое внимание следует обратить на определение общего количества нефтяных углеводородов (TPH) способом хроматографии газа в связи с тем, что может быть не полноcтью оценена возможная опасность летучих ароматических соединений (BTEX).

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Section: Resultsmentioning

confidence: 99%

Determination of Oil and Grease, Total Petroleum Hydrocarbons and Volatile Aromatic Compounds in Soil and Sediment Samples

Rauckyte

Żak

Pawlak³

et al. 2010

Journal of Environmental Engineering and Landscape Management

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“…With the variety of both toxic effects and living organisms, perfect methods for assessing mixture toxicity do not exist (Yang et al, 1989). While these efforts are often designed for public health or ecosystem protection (Backhaus et al, 2010; Borgert et al, 2004; Groten et al, 2004; Mumtaz et al, 2004) they also often have differing goals with respect to mixture toxicity.…”

Section: Discussionmentioning

confidence: 99%

Evaluation of an asymmetry parameter for curve-fitting in single-chemical and mixture toxicity assessment

Dawson¹,

Genco²,

Bensinger³

et al. 2012

Toxicology

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In mixture toxicity, concentration-effect data are often used to generate conclusions on combined effect. While models of combined effect are available for such assessments, proper fitting of the data is critical to obtaining accurate conclusions. In this study an asymmetry parameter (s) was evaluated for data-fitting and compared with our previous approach. Inhibition of bioluminescence was assessed with Vibrio fischeri at 15, 30 and 45-minutes of exposure with seven or eight concentrations and a control (each duplicated) for each single-chemical (A or B) and mixture (A:B). Concentration-effect data were fitted to sigmoid curves using the four-parameter logistic function (4PL) and the five-parameter logistic minus one-parameter (5PL-1P) function. For the 4PL, parameters included minimum effect, maximum effect, EC50 and slope, while for the 5PL-1P the minimum effect parameter was removed and an asymmetry parameter was added. A total of 72 mixture toxicity data sets were evaluated, representing 432 single-chemical and 216 mixture curves. Mean coefficients of determination (r2) for all 648 curves showed that the 5PL-1P gave better fitting (0.9982 ± 0.0018) than the 4PL (0.9973 ± 0.0030). For both functions, the sum-of-squares of the residuals (SS-Res) was determined for each curve. The 5-parameter rational regression best described the relationship between the decrease in sum-of-squares of the residuals (i.e., 4PL: SS-Res – 5PL-1P: SS-Res) and log s, with fitting improved the most at low values of s (s < 0.8). This held even when curves with r2 values ≤ 0.9970 were removed from the analyses. Subsequent review of the combined effects obtained via the 4PL and the 5PL-1P functions resulted in a change in the interpretation of combined effect in 39/216 (18%) cases.

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“…However, toxicological guidelines are determined on the basis of data that are generally obtained in studies that consider singlechemical exposures (Haddad et al, 2010). The possible consequences to human health of exposure to multiple chemicals have yielded a growing concern in the public and scientific community (Lampa et al, 2014;Boobis et al, 2011;Meek et al, 2011;Mumtaz et al, 2004Mumtaz et al, , 2007. This has prompted numerous investigators to undertake studies to evaluate the combined adverse consequences of exposure to chemical mixtures (Starr et al, 2012;Hendriksen et al, 2007;Pounds et al, 2004;Tang et al, 2003;Baynes et al, 2002;Mumtaz et al, 2002;Tully et al, 2000aTully et al, , 2000bSoni et al, 1999).…”

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confidence: 96%

Assessing Human Variability in Kinetics for Exposures to Multiple Environmental Chemicals: A Physiologically Based Pharmacokinetic Modeling Case Study with Dichloromethane, Benzene, Toluene, Ethylbenzene, andm-Xylene

Valcke

Haddad

2015

Journal of Toxicology and Environmental Health, Part A

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The objective of this study was to compare the magnitude of interindividual variability in internal dose for inhalation exposure to single versus multiple chemicals. Physiologically based pharmacokinetic models for adults (AD), neonates (NEO), toddlers (TODD), and pregnant women (PW) were used to simulate inhalation exposure to "low" (RfC-like) or "high" (AEGL-like) air concentrations of benzene (Bz) or dichloromethane (DCM), along with various levels of toluene alone or toluene with ethylbenzene and xylene. Monte Carlo simulations were performed and distributions of relevant internal dose metrics of either Bz or DCM were computed. Area under the blood concentration of parent compound versus time curve (AUC)-based variability in AD, TODD, and PW rose for Bz when concomitant "low" exposure to mixtures of increasing complexities occurred (coefficient of variation (CV) = 16-24%, vs. 12-15% for Bz alone), but remained unchanged considering DCM. Conversely, AUC-based CV in NEO fell (15 to 5% for Bz; 12 to 6% for DCM). Comparable trends were observed considering production of metabolites (AMET), except for NEO's CYP2E1-mediated metabolites of Bz, where an increased CV was observed (20 to 71%). For "high" exposure scenarios, Cmax-based variability of Bz and DCM remained unchanged in AD and PW, but decreased in NEO (CV= 11-16% to 2-6%) and TODD (CV= 12-13% to 7-9%). Conversely, AMET-based variability for both substrates rose in every subpopulation. This study analyzed for the first time the impact of multiple exposures on interindividual variability in toxicokinetics. Evidence indicates that this impact depends upon chemical concentrations and biochemical properties, as well as the subpopulation and internal dose metrics considered.

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Seeking solutions to chemical mixtures challenges in public health

Cited by 7 publications

References 23 publications

Determination of Oil and Grease, Total Petroleum Hydrocarbons and Volatile Aromatic Compounds in Soil and Sediment Samples

Determination of Oil and Grease, Total Petroleum Hydrocarbons and Volatile Aromatic Compounds in Soil and Sediment Samples

Evaluation of an asymmetry parameter for curve-fitting in single-chemical and mixture toxicity assessment

Assessing Human Variability in Kinetics for Exposures to Multiple Environmental Chemicals: A Physiologically Based Pharmacokinetic Modeling Case Study with Dichloromethane, Benzene, Toluene, Ethylbenzene, andm-Xylene

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