Volatile organic compounds in human milk: methods and measurements

Species profile of volatile organic compounds emission and health risk assessment from typical indoor events in daycare centers

Daycare centers (DCCs) play an instrumental role in early childhood development, making them a significant indoor environment for a large number of children globally. Amidst routine DCC activities, young children are exposed to a myriad of volatile organic compounds (VOCs), potentially impacting their health. Therefore, this study aims to investigate the VOC emissions during typical DCCs activities and evaluate respective health risk assessments. Employing a full-scale experimental setup within a well-controlled climate chamber, research was conducted into VOC emissions during three typical DCC events: arts-and-crafts (painting, gluing, modeling), cleaning, and sleeping activities tied to mattresses. The research identified 96 distinct VOCs, grouped into twelve categories, from 20 different events examined. Each event exhibited a unique VOC fingerprint, pinpointing potential source tracers. Also, significant variations in VOC emissions from different events were demonstrated. For instance, under cool & dry conditions, acrylic painting recorded high total VOC concentrations of 808 μg/m3, whereas poster painting showed only 58 μg/m3. Given these disparities, the study emphasizes the critical need for carefully selecting arts-and-crafts materials and cleaning agents in DCCs to effectively reduce VOC exposure. It suggests ventilating new mattresses before use and regular mattress check-ups to mitigate VOCs exposure during naps. Importantly, it revealed that certain events resulted in VOC levels exceeding the 10-5 cancer risk thresholds for younger children. Specifically, tetrachloroethylene and styrene from used mattresses in cool & dry conditions, ethylene oxide from new mattresses in warm & humid conditions, and styrene, during sand modeling in both conditions, were the key compounds contributing to this risk. These findings highlight the critical need for age-specific health risk assessments in DCCs. This study highlights the significance of understanding the profiles of VOC emissions from indoor events in DCCs, emphasizing potential health implications and laying a solid foundation for future investigations in this field.

Polyphenol exposure of mothers and infants assessed by LC-MS/MS based biomonitoring in breast milk

Exposure to polyphenols is relevant throughout critical windows of infant development, including the breastfeeding phase. However, the quantitative assessment of polyphenols in human breast milk has received limited attention so far, though polyphenols may positively influence infant health. Therefore, a targeted LC-MS/MS assay was developed to investigate 86 analytes representing different polyphenol classes in human breast milk. The sample preparation consisted of liquid extraction, salting out, freeze-out, and a dilution step. Overall, nearly 70% of the chemically diverse polyphenols fulfilled all strict validation criteria for full quantitative assessment. The remaining analytes did not fulfill all criteria at every concentration level, but can still provide useful semi-quantitative insights into nutritional and biomedical research questions. The limits of detection for all analyzed polyphenols were in the range of 0.0041-87 ng*mL-1, with a median of 0.17 ng*mL-1. Moreover, the mean recovery was determined to be 82% and the mean signal suppression and enhancement effect was 117%. The developed assay was applied in a proof-of-principle study to investigate polyphenols in breast milk samples provided by twelve Nigerian mothers at three distinct time points post-delivery. In total, 50 polyphenol analytes were detected with almost half being phenolic acids. Phase II metabolites, including genistein-7-β-D-glucuronide, genistein-7-sulfate, and daidzein-7-β-D-glucuronide, were also detected in several samples. In conclusion, the developed method was demonstrated to be fit-for-purpose to simultaneously (semi-) quantify a wide variety of polyphenols in breast milk. It also demonstrated that various polyphenols including their biotransformation products were present in breast milk and therefore likely transferred to infants where they might impact microbiome development and infant health.

Emissions of Formamide and Ammonia from Foam Mats: Online Measurement Based on Dopant-Assisted Photoionization TOFMS and Assessment of Their Exposure for Children

Formamide has been classified as a Class 1B reproductive toxicant to children by the European Union (EU) Chemicals Agency. Foam mats are a potential source of formamide and ammonia. Online dopant-assisted atmospheric pressure photoionization time-of-flight mass spectrometry (DA-APPI-TOFMS) coupled with a Teflon environmental chamber was developed to assess the exposure risk of formamide and ammonia from foam mats to children. High levels of formamide (average 3363.72 mg/m³) and ammonia (average 1586.78 mg/m³) emissions were measured from 21 foam mats with three different raw material types: ethylene-vinyl acetate (EVA: n = 7), polyethylene (PE: n = 7), and cross-linked polyethylene (XPE: n = 7). The 28 day emission testing for the selected PE mat showed that the emissions of formamide were 2 orders of magnitude higher than the EU emission limit of 20 μg/m³, and formamide may be a permanent indoor contaminant for foam mat products during their life cycle. The exposure assessment of children aged 0.5-6 years showed that the exposure dose was approximately hundreds of mg/kg-day, and the age group of 0.5-2 years was subject to much higher dermal exposures than others. Thus, this study provided key relevant information for further studies on assessing children's exposure to indoor air pollution from foam mats.

Characterization of different contaminants and current knowledge for defining chemical mixtures in human milk: A review

Hundreds of xenobiotics, with very diverse origins, have been detected in human milk, including contaminants of emerging concern, personal care products and other current-use substances reflecting lifestyle. The routes of exposure to these chemicals include dermal absorption, ingestion and inhalation. Specific families of chemicals are dominant among human milk monitoring studies (e.g., organochlorine pesticides, bisphenol A, dioxins), even though other understudied families may be equally toxicologically relevant (e.g., food-processing chemicals, current-use plasticizers and flame retardants, mycotoxins). Importantly, the lack of reliable human milk monitoring data for some individual chemicals and, especially, for complex mixtures, is a major factor hindering risk assessment. Non-targeted screening can be used as an effective tool to identify unknown contaminants of concern in human milk. This approach, in combination with novel methods to conduct risk assessments on the chemical mixtures detected in human milk, will assist in elucidating exposures that may have adverse effects on the development of breastfeeding infants.

Food-Borne Chemical Carcinogens and the Evidence for Human Cancer Risk

Commonly consumed foods and beverages can contain chemicals with reported carcinogenic activity in rodent models. Moreover, exposures to some of these substances have been associated with increased cancer risks in humans. Food-borne carcinogens span a range of chemical classes and can arise from natural or anthropogenic sources, as well as form endogenously. Important considerations include the mechanism(s) of action (MoA), their relevance to human biology, and the level of exposure in diet. The MoAs of carcinogens have been classified as either DNA-reactive (genotoxic), involving covalent reaction with nuclear DNA, or epigenetic, involving molecular and cellular effects other than DNA reactivity. Carcinogens are generally present in food at low levels, resulting in low daily intakes, although there are some exceptions. Carcinogens of the DNA-reactive type produce effects at lower dosages than epigenetic carcinogens. Several food-related DNA-reactive carcinogens, including aflatoxins, aristolochic acid, benzene, benzo[a]pyrene and ethylene oxide, are recognized by the International Agency for Research on Cancer (IARC) as causes of human cancer. Of the epigenetic type, the only carcinogen considered to be associated with increased cancer in humans, although not from low-level food exposure, is dioxin (TCDD). Thus, DNA-reactive carcinogens in food represent a much greater risk than epigenetic carcinogens.

Odor-active volatile compounds in preterm breastmilk

BACKGROUND

Volatile compounds in breastmilk (BM) likely influence flavor learning and, through the cephalic phase response, metabolism, and digestion. Little is known about the volatile compounds present in preterm BM. We investigated whether maternal or infant characteristics are associated with the profile of volatile compounds in preterm BM.

METHODS

Using solid-phase microextraction coupled with gas chromatography/mass spectrometry, we analyzed volatile compounds in 400 BM samples collected from 170 mothers of preterm infants.

RESULTS

Forty volatile compounds were detected, mostly fatty acids and their esters (FA and FAe), volatile organic compounds (VOCs), aldehydes, terpenoids, alcohols, and ketones. The relative concentration of most FA and FAe increased with advancing lactation and were lower in BM of most socially deprived mothers and those with gestational diabetes (p < 0.05), but medium-chain FAs were higher in colostrum compared to transitional BM (p < 0.001). Infant sex, gestational age, and size at birth were not associated with the profile of volatile compounds in preterm BM.

CONCLUSIONS

Sensory-active volatile FA and FAe are the major contributors to the smell of preterm BM. The associations between lactation stage, maternal characteristics, and volatile compounds, and whether differences in volatile compounds may affect feeding behavior or metabolism, requires further research.

IMPACT

Sensory-active volatile FAs are major contributors to the smell of preterm BM and are influenced by the lactation stage and maternal characteristics. Longitudinal analysis of volatile compounds in preterm BM found that FAs increased with advancing lactation. Colostrum had a higher concentration of medium-chain FAs compared to transitional BM and the concentration of these is associated with socioeconomic status, gestational diabetes, and ethnicity.

Migration of cyclohexanone and 3,3,5-trimethylcyclohexanone from a neonatal enteral feeding system into human milk

OBJECTIVE

Estimate the migration of volatile organic compounds (VOCs) which have been identified by the EPA as a public health concern, from the enteral feeding system into human milk.

STUDY DESIGN

Unfortified human milk samples were infused through an enteral feeding system with varying duration of infusion, incubator temperature, and pre-infusion tube priming. Purge & Trap analysis and GC/MS were used to identify the VOC profile of milk pre- and post-infusion.

RESULT

Cyclohexanone and 3,3,5-trimethylcyclohexanone (3,3,5-TMC) accumulated significantly in milk samples post-infusion. Duration of infusion had a significant effect on VOC accumulation (p = 0.001). Accumulation patterns of cyclohexanone and 3,3,5-TMC differed significantly based on milk type (donor vs. mother's own milk).

CONCLUSIONS

VOCs, migrate from plastic-based feeding equipment into human milk. Based on these findings, limiting the duration of feeding infusion would reduce VOC exposure derived from enteral feeding in the neonatal intensive care unit.

A literature survey of all volatiles from healthy human breath and bodily fluids: the human volatilome

This paper comprises an updated version of the 2014 review which reported 1846 volatile organic compounds (VOCs) identified from healthy humans. In total over 900 additional VOCs have been reported since the 2014 review and the VOCs from semen have been added. The numbers of VOCs found in breath and the other bodily fluids are: blood 379, breath 1488, faeces 443, milk 290, saliva 549, semen 196, skin 623 and urine 444. Compounds were assigned CAS registry numbers and named according to a common convention where possible. The compounds have been included in a single table with the source reference(s) for each VOC, an update on our 2014 paper. VOCs have also been grouped into tables according to their chemical class or functionality to permit easy comparison. Careful use of the database is needed, as a number of the identified VOCs only have level 2-putative assignment, and only a small fraction of the reported VOCs have been validated by standards. Some clear differences are observed, for instance, a lack of esters in urine with a high number in faeces and breath. However, the lack of compounds from matrices such a semen and milk compared to breath for example could be due to the techniques used or reflect the intensity of effort e.g. there are few publications on VOCs from milk and semen compared to a large number for breath. The large number of volatiles reported from skin is partly due to the methodologies used, e.g. by collecting skin sebum (with dissolved VOCs and semi VOCs) onto glass beads or cotton pads and then heating to a high temperature to desorb VOCs. All compounds have been included as reported (unless there was a clear discrepancy between name and chemical structure), but there may be some mistaken assignations arising from the original publications, particularly for isomers. It is the authors' intention that this work will not only be a useful database of VOCs listed in the literature but will stimulate further study of VOCs from healthy individuals; for example more work is required to confirm the identification of these VOCs adhering to the principles outlined in the metabolomics standards initiative. Establishing a list of volatiles emanating from healthy individuals and increased understanding of VOC metabolic pathways is an important step for differentiating between diseases using VOCs.

Olfactory Cues in Infant Feeds: Volatile Profiles of Different Milks Fed to Preterm Infants

Background: Smell is determined by odor-active volatile compounds that bind to specific olfactory receptors, allowing us to discriminate different smells. Olfactory stimulation may assist with digestion and metabolism of feeds in the neonate by activation of the cephalic phase response of digestion. Infants' physiological responses to the smell of different milks suggest they can distinguish between breastmilk and infant formula. We aimed to describe the profile of volatile compounds in preterm breastmilk and investigate how this differed from that of other preterm infant feeding options including pasteurized donor breastmilk, breastmilk with bovine milk-based fortifier, human milk-based products and various infant formulas. Methods: Forty-seven milk samples (13 different infant formulas and 34 human milk-based samples) were analyzed. Volatile compounds were extracted using Solid Phase Micro Extraction. Identification and relative quantification were carried out by Gas Chromatography with Mass Spectrometry. Principal Component Analysis (PCA) and one-way Analysis of Variance (ANOVA) with Tukey's HSD (parametric data) or Conover's post-hoc test (non-parametric data) were used as appropriate to explore differences in volatile profiles among milk types. Results: In total, 122 compounds were identified. Breastmilk containing bovine milk-based fortifier presented the highest number of compounds (109) and liquid formula the lowest (70). The profile of volatile compounds varied with 51 compounds significantly different (adjusted p < 0.001) among milk types. PCA explained 47% of variability. Compared to preterm breastmilk, the profile of volatile compounds in breastmilk with added bovine milk-based fortifier was marked by presence of fatty acids and their esters, ketones and aldehydes; infant formulas were characterized by alkyls, aldehydes and furans, and human milk-based products presented high concentrations of aromatic hydrocarbons, terpenoids and specific fatty acids. Conclusions: Sensory-active products of fatty acid oxidation are the major contributors to olfactory cues in infant feeds. Analysis of volatile compounds might be useful for monitoring quality of milk and detection of oxidation products and environmental contaminants. Further research is needed to determine whether these different volatile compounds have biological or physiological effects in nutrition of preterm infants.

Environmental Chemicals in Breast Milk and Formula: Exposure and Risk Assessment Implications

BACKGROUND

Human health risk assessment methods have advanced in recent years to more accurately estimate risks associated with exposure during childhood. However, predicting risks related to infant exposures to environmental chemicals in breast milk and formula remains challenging.

OBJECTIVES

Our goal was to compile available information on infant exposures to environmental chemicals in breast milk and formula, describe methods to characterize infant exposure and potential for health risk in the context of a risk assessment, and identify research needed to improve risk analyses based on this type of exposure and health risk information.

METHODS

We reviewed recent literature on levels of environmental chemicals in breast milk and formula, with a focus on data from the United States. We then selected three example publications that quantified infant exposure using breast milk or formula chemical concentrations and estimated breast milk or formula intake. The potential for health risk from these dietary exposures was then characterized by comparison with available health risk benchmarks. We identified areas of this approach in need of improvement to better characterize the potential for infant health risk from this critical exposure pathway.

DISCUSSION

Measurements of chemicals in breast milk and formula are integral to the evaluation of risk from early life dietary exposures to environmental chemicals. Risk assessments may also be informed by research investigating the impact of chemical exposure on developmental processes known to be active, and subject to disruption, during infancy, and by analysis of exposure-response data specific to the infant life stage. Critical data gaps exist in all of these areas.

CONCLUSIONS

Better-designed studies are needed to characterize infant exposures to environmental chemicals in breast milk and infant formula as well as to improve risk assessments of chemicals found in both foods. https://doi.org/10.1289/EHP1953.

Evaluation of Potential Average Daily Doses (ADDs) of PM2.5 for Homemakers Conducting Pan-Frying Inside Ordinary Homes under Four Ventilation Conditions

Several studies reported that commercial barbecue restaurants likely contribute to the indoor emission of particulate matters with a diameter of 2.5 micrometers or less (PM_2.5) while pan-frying meat. However, there is inadequate knowledge of exposure level to indoor PM_2.5 in homes and the contribution of a typical indoor pan-frying event. We measured the indoor PM_2.5 concentration and, using Monte-Carlo simulation, estimated potential average daily dose (ADD) of PM_2.5 for homemakers pan-frying a piece of pork inside ordinary homes. Convenience-based sampling at 13 homes was conducted over four consecutive days in June 2013 (n = 52). Although we pan-fried 100 g pork for only 9 min, the median (interquartile range, IQR) value was 4.5 (2.2-5.6) mg/m³ for no ventilation and 0.5 (0.1-1.3) mg/m³ with an active stove hood ventilation system over a 2 h sampling interval. The probabilities that the ADDs from inhalation of indoor PM_2.5 would be higher than the ADD from inhalation of PM_2.5 on an outdoor roadside (4.6 μg/kg·day) were 99.44%, 97.51%, 93.64%, and 67.23%, depending on the ventilation conditions: (1) no window open; (2) one window open in the kitchen; (3) two windows open, one each in the kitchen and living room; and (4) operating a forced-air stove hood, respectively.

Nanoscale Sensor Technologies for Disease Detection via Volatolomics

The detection of many diseases is missed because of delayed diagnoses or the low efficacy of some treatments. This emphasizes the urgent need for inexpensive and minimally invasive technologies that would allow efficient early detection, stratifying the population for personalized therapy, and improving the efficacy of rapid bed-side assessment of treatment. An emerging approach that has a high potential to fulfill these needs is based on so-called "volatolomics", namely, chemical processes involving profiles of highly volatile organic compounds (VOCs) emitted from body fluids, including breath, skin, urine and blood. This article presents a didactic review of some of the main advances related to the use of nanomaterial-based solid-state and flexible sensors, and related artificially intelligent sensing arrays for the detection and monitoring of disease with volatolomics. The article attempts to review the technological gaps and confounding factors related to VOC testing. Different ways to choose nanomaterial-based sensors are discussed, while considering the profiles of targeted volatile markers and possible limitations of applying the sensing approach. Perspectives for taking volatolomics to a new level in the field of diagnostics are highlighted.

Risk assessments for chronic exposure of children and prospective parents to ethylbenzene (CAS No. 100-41-4)

Potential chronic health risks for children and prospective parents exposed to ethylbenzene were evaluated in response to the Voluntary Children's Chemical Evaluation Program. Ethylbenzene exposure was found to be predominately via inhalation with recent data demonstrating continuing decreases in releases and both outdoor and indoor concentrations over the past several decades. The proportion of ethylbenzene in ambient air that is attributable to the ethylbenzene/styrene chain of commerce appears to be relatively very small, less than 0.1% based on recent relative emission estimates. Toxicity reference values were derived from the available data, with physiologically based pharmacokinetic models and benchmark dose methods used to assess dose-response relationships. An inhalation non-cancer reference concentration or RfC of 0.3 parts per million (ppm) was derived based on ototoxicity. Similarly, an oral non-cancer reference dose or RfD of 0.5 mg/kg body weight/day was derived based on liver effects. For the cancer assessment, emphasis was placed upon mode of action information. Three of four rodent tumor types were determined not to be relevant to human health. A cancer reference value of 0.48 ppm was derived based on mouse lung tumors. The risk characterization for ethylbenzene indicated that even the most highly exposed children and prospective parents are not at risk for non-cancer or cancer effects of ethylbenzene.

Volatile profile of breast milk subjected to high-pressure processing or thermal treatment

The effect of Holder pasteurisation (HoP) (62.5°C for 30 min) or high-pressure treatments (400 or 600 MPa for 3 or 6 min) on the volatile compound profile of human breast milk was evaluated, in order to compare both preservation technologies. A total of 46 different volatile compounds was found in milk samples. The most abundant compounds detected were aliphatic hydrocarbons. In general, the effect of some high-pressure treatments on the volatile profile of human milk was less intense than that caused by HoP. The treatments at 400 and 600 MPa for 3 min maintained the volatile compounds at similar levels to those found in control milk samples. However, the application of 600 MPa for 6 min changed the original volatile compounds of human milk, even more than HoP. Since, HPP at 400 or 600 MPa for 3 min preserved the original volatile compounds of human milk, this novel process may be an alternative to thermal pasteurisation.

Reconnaissance of 47 antibiotics and associated microbial risks in seafood sold in the United States

Aquaculture production has nearly tripled in the last two decades, bringing with it a significant increase in the use of antibiotics. Using liquid chromatography/tandem mass spectrometry (LC-MS/MS), the presence of 47 antibiotics was investigated in U.S. purchased shrimp, salmon, catfish, trout, tilapia, and swai originating from 11 different countries. All samples (n=27) complied with U.S. FDA regulations and five antibiotics were detected above the limits of detection: oxytetracycline (in wild shrimp, 7.7ng/g of fresh weight; farmed tilapia, 2.7; farmed salmon, 8.6; farmed trout with spinal deformities, 3.9), 4-epioxytetracycline (farmed salmon, 4.1), sulfadimethoxine (farmed shrimp, 0.3), ormetoprim (farmed salmon, 0.5), and virginiamycin (farmed salmon marketed as antibiotic-free, 5.2). A literature review showed that sub-regulatory levels of antibiotics, as found here, can promote resistance development; publications linking aquaculture to this have increased more than 8-fold from 1991 to 2013. Although this study was limited in size and employed sample pooling, it represents the largest reconnaissance of antibiotics in U.S. seafood to date, providing data on previously unmonitored antibiotics and on farmed trout with spinal deformities. Results indicate low levels of antibiotic residues and general compliance with U.S. regulations. The potential for development of microbial drug resistance was identified as a key concern and research priority.

Infant exposure to emissions of volatile organic compounds from crib mattresses

Infants spend most of their time sleeping and are likely to be exposed to elevated concentrations of chemicals released from their crib mattresses. Small-scale chamber experiments were conducted to determine the area-specific emission rates (SERs) of volatile organic compounds (VOCs) in a collection of twenty new and used crib mattresses. All mattress samples were found to emit VOCs and the mean values of total VOC (TVOC) SERs were 56 μg/m(2)h at 23 °C and 139 μg/m(2)h at 36 °C. TVOC SERs were greater for new mattresses compared to used ones and were influenced by the type of foam material and the presence of mattress cover layer. A variety of VOCs were identified, with polyurethane foam releasing a greater diversity of VOCs compared to polyester foam. Large-scale chamber experiments were conducted with an infant thermal manikin. TVOC concentrations sampled in the breathing zone and interior pore air of the crib mattress foam were found to be greater than the bulk room air by factors in the range of 1.8 to 2.4 and 7.5 to 21, respectively. The results suggest that crib mattresses are an important source of VOCs and infant exposure to VOCs are possibly elevated in their sleep microenvironments.

A review of the volatiles from the healthy human body

A compendium of all the volatile organic compounds (VOCs) emanating from the human body (the volatolome) is for the first time reported. 1840 VOCs have been assigned from breath (872), saliva (359), blood (154), milk (256), skin secretions (532) urine (279), and faeces (381) in apparently healthy individuals. Compounds were assigned CAS registry numbers and named according to a common convention where possible. The compounds have been grouped into tables according to their chemical class or functionality to permit easy comparison. Some clear differences are observed, for instance, a lack of esters in urine with a high number in faeces. Careful use of the database is needed. The numbers may not be a true reflection of the actual VOCs present from each bodily excretion. The lack of a compound could be due to the techniques used or reflect the intensity of effort e.g. there are few publications on VOCs from blood compared to a large number on VOCs in breath. The large number of volatiles reported from skin is partly due to the methodologies used, e.g. collecting excretions on glass beads and then heating to desorb VOCs. All compounds have been included as reported (unless there was a clear discrepancy between name and chemical structure), but there may be some mistaken assignations arising from the original publications, particularly for isomers. It is the authors' intention that this database will not only be a useful database of VOCs listed in the literature, but will stimulate further study of VOCs from healthy individuals. Establishing a list of volatiles emanating from healthy individuals and increased understanding of VOC metabolic pathways is an important step for differentiating between diseases using VOCs.

Analysis of exhaled breath for disease detection

Breath analysis is a young field of research with great clinical potential. As a result of this interest, researchers have developed new analytical techniques that permit real-time analysis of exhaled breath with breath-to-breath resolution in addition to the conventional central laboratory methods using gas chromatography-mass spectrometry. Breath tests are based on endogenously produced volatiles, metabolites of ingested precursors, metabolites produced by bacteria in the gut or the airways, or volatiles appearing after environmental exposure. The composition of exhaled breath may contain valuable information for patients presenting with asthma, renal and liver diseases, lung cancer, chronic obstructive pulmonary disease, inflammatory lung disease, or metabolic disorders. In addition, oxidative stress status may be monitored via volatile products of lipid peroxidation. Measurement of enzyme activity provides phenotypic information important in personalized medicine, whereas breath measurements provide insight into perturbations of the human exposome and can be interpreted as preclinical signals of adverse outcome pathways.

Concentration of trichloroethylene in breast milk and household water from Nogales, Arizona

The United States Environmental Protection Agency has identified quantification of trichloroethylene (TCE), an industrial solvent, in breast milk as a high priority need for risk assessment. Water and milk samples were collected from 20 households by a lactation consultant in Nogales, Arizona. Separate water samples (including tap, bottled, and vending machine) were collected for all household uses: drinking, bathing, cooking, and laundry. A risk factor questionnaire was administered. Liquid-liquid extraction with diethyl ether was followed by GC-MS for TCE quantification in water. Breast milk underwent homogenization, lipid hydrolysis, and centrifugation prior to extraction. The limit of detection was 1.5 ng/mL. TCE was detected in 7 of 20 mothers' breast milk samples. The maximum concentration was 6 ng/mL. TCE concentration in breast milk was significantly correlated with the concentration in water used for bathing (ρ = 0.59, p = 0.008). Detection of TCE in breast milk was more likely if the infant had a body mass index <14 (RR = 5.2, p = 0.02). Based on average breast milk consumption, TCE intake for 5% of the infants may exceed the proposed U.S. EPA Reference Dose. Results of this exploratory study warrant more in depth studies to understand risk of TCE exposures from breast milk intake.

Analytical methods used in conjunction with solid-phase microextraction: a review of recent bioanalytical applications

Integration of sampling and sample preparation with various analytical instruments is a highly desirable feature for any analytical method. This is most conveniently achieved by using microextraction techniques or various microdevices. Among these techniques, solid-phase microextraction (SPME) is particularly remarkable due to its simplicity and effectiveness. This review discusses the most recent applications of SPME in bioanalysis, grouped according to the analytical instrument that SPME is coupled to. It is shown that one of the most important aspects of such analytical methods is the ability of SPME to perform direct and selective extraction of analytes from complex biological samples. By far, the most popular method continues to be SPME coupled to GC. Nevertheless, the last 2 years have witnessed significant advances in other areas, such as successful automation of SPME coupled to liquid chromatography and the development of new coatings suitable for direct extraction from biological samples. Furthermore, a few bioanalytical applications based on direct coupling of SPME to MS, ion mobility spectrometry, CE and analytical chemiluminescence have been reported.

Polycyclic aromatic hydrocarbons in human milk of nonsmoking U.S. women

The determination of polycyclic aromatic hydrocarbons (PAHs) in human milk is relevant in assessing the dose to mothers and infants. Since measurements for the United States are lacking, we analyzed 13 PAHs in human milk from 12 nonsmoking American mothers. Analytes were extracted from milk by using a combination of centrifugation, liquid-liquid, and solid-phase extraction techniques. Following method validation with spiked bovine milk, PAH concentrations in human milk were determined by isotope dilution gas chromatography/mass spectrometry. Phenanthrene, fluorene, fluoranthene, and pyrene were found at median concentrations of 11.8, 3.0, 1.6, and 1.1 ng/g milk fat, respectively, whereas 9 additional analytes including benzo[a]pyrene were not detected (<0.04 ng/g). Calculated average daily doses from ingestion (high: 75.8, phenanthrene; low: 6.1 ng/kg/day pyrene) were compared to doses from air pollution inhalation. Milk ingestion accounted for 47.9-81.4% of the total dose of individual PAHs to the infant. However, calculated total average daily doses of phenanthrene and pyrene from ingestion and inhalation combined (12.2 to 110.3 ng/kg-day, respectively) were 3 orders of magnitude lower than documented doses known to cause health effects. These first measurements of PAH levels in U.S. human milk are comparable to concentrations reported previously for European and Asian women.