Occurrence of Melamine and Its Derivatives in Breast Milk from the United States and Its Implications for Exposure in Infants

Early-life exposure to per- and polyfluoroalkyl substances: Analysis of levels, health risk and binding abilities to transport proteins

Per- and polyfluoroalkyl substances (PFAS) can pass through the placenta and adversely affect fetal development. However, there is a lack of comparison of legacy and emerging PFAS levels among different biosamples in pregnant women and their offspring. This study, based on the Shanghai Maternal-Child Pairs Cohort, analyzed the concentrations of 16 PFAS in the maternal serum, cord serum, and breast milk samples from 1,076 mother-child pairs. The placental and breastfeeding transfer efficiencies of PFAS were determined in maternal-cord and maternal-milk pairs, respectively. The binding affinities of PFAS to five transporters were simulated using molecular docking. The results suggested that PFAS were frequently detected in different biosamples. The median concentration of perfluorooctane sulfonate (PFOS) was the highest at 8.85 ng/mL, followed by perfluorooctanoic acid (PFOA) at 7.13 ng/mL and 6:2 chlorinated polyfluorinated ether sulfonate at 5.59 ng/mL in maternal serum. The median concentrations of PFOA were highest in cord serum (4.23 ng/mL) and breast milk (1.08 ng/mL). PFAS demonstrated higher placental than breastfeeding transfer efficiencies. The transfer efficiencies and the binding affinities of most PFAS to proteins exhibited alkyl chain length-dependent patterns. Furthermore, we comprehensively assessed the estimated daily intakes (EDIs) of PFAS in breastfeeding infants of different age groups and used the hazard quotient (HQ) to characterize the potential health risk. EDIs decreased with infant age, and PFOS had higher HQs than PFOA. These findings highlight the significance of considering PFAS exposure, transfer mechanism, and health risks resulting from breast milk intake in early life.

Dynamic Source Distribution and Emission Inventory of a Persistent, Mobile, and Toxic (PMT) Substance, Melamine, in China

Persistent, mobile, and toxic (PMT) substances are affecting the safety of drinking water and are threatening the environment and human health. Many PMT substances are used in industrial processing or consumer products, but their sources and emissions mostly remain unclear. This study presents a long-term source distribution and emission estimation of melamine, a high-production-volume PMT substance of emerging global concern. The results indicate that in China, approximately 1858.7 kilotonnes (kt) of melamine were released into the water (∼58.9%), air (∼27.0%), and soil systems (∼14.1%) between 1995 and 2020, mainly from its production and use in the decorative panels, textiles, and paper industries. The textile and paper industries have the highest emission-to-consumption ratios, with more than 90% emissions per unit consumption. Sewage treatment plants are the largest source of melamine in the environment for the time being, but in-use products and their wastes will serve as significant melamine sources in the future. The study prompts priority action to control the risk of PMT substances internationally.

An air-assisted dispersive liquid phase microextraction method based on a hydrophobic magnetic deep eutectic solvent for the extraction and preconcentration of melamine from milk and milk-based products

In the current research, a fast and sustainable air-assisted hydrophobic magnetic deep eutectic solvent-based dispersive liquid phase microextraction followed by UV-Vis spectrophotometry measurements was optimized for the extraction and determination of melamine in milk and milk-based products. The central composite design was applied for the optimization of factors affecting the recovery of melamine. Quantitative extraction of melamine was achieved using hydrophobic magnetic deep eutectic solvents prepared from a mixture of octanoic acid, aliquat-336, and cobalt(II) chloride. The optimum conditions for extraction were found as follows: 6 extraction cycles, pH 8.2, extraction solvent volume 260 µL, and acetone volume 125 µL.Interestingly, a centrifugation step was not required to achieve phase separation. Under the optimum conditions, melamine was determined in the linear range of 3-600 ng mL^-1, the limit of detection (3S_blank/m) of 0.9 ng mL^-1, and the enrichment factor of 144. The validation of the method was investigated by the analysis of reference materials. Consequently, the method was successfully applied for the analysis of melamine residues in milk and milk-based products.

Exposure to nitrogenous based flame retardants in Chinese population: Evidence from a national-scale study

Extensive use of nitrogen-based flame retardants (NFRs) has resulted in their widespread environmental occurrence. To investigate human exposure to NFRs on a national scale, the abundance and spatial distribution of NFRs were assessed in urine specimens collected from 13 cities in China. Six out of eight target NFRs were detectable in more than half of the urine samples, and the total concentrations of NFRs ranged from 3.22 to 880 ng/mL with a median of 46.7 ng/mL. Cyanuric acid was the most abundant chemical, accounting for 66.2%, followed by melamine (16.3%), ammelide (10.8%), and ammeline (6.11%). Regional differences in concentrations and composition profiles of NFRs were observed within China as a result of different production and application profiles. In addition, we found that urinary NFRs levels were much higher than but statistically correlated with that of organophosphates (r² = 0.69, p < 0.05), another class of phosphorus-based flame retardant, implying similar emission sources and/or human exposure pathways. Furthermore, the estimated daily intakes and hazard quotients revealed that the Chinese population's exposure to NFRs is within safe limits. To the best of our knowledge, this is the first study to document the ubiquitous occurrence and region-specific variations of human exposure to NFRs in China.

Comparison of melamine exposure by feeding practices in babies aged 0-6 months

This study was conducted to estimate the daily dietary intakes of melamine for human milk-fed (HMF) babies and mixed-fed (MF) babies. It was carried out in 70 mother-baby pairs (40 babies in the HMF group and 30 babies in the MF group). Human milk, formula milk, and baby urine samples were collected to assess the dietary exposure of babies. Melamine concentrations were analyzed by using a competitive enzyme-linked immunosorbent assay. Melamine was determined in 82.5 % of the human milk samples in the HMF group (median: 0.75 µg/L) while it was present in 96.7 % of human milk samples (median: 1.25 µg/L) and 96.7 % in formula milk samples (median: 0.95 µg/kg) in the MF group. The mean urinary melamine concentration of HMF babies (1.20 ± 0.21 µg/L) was not significantly different than MF babies (1.35 ± 0.49 µg/L). Melamine exposure was calculated as 0.12 µg/kg bw/day and 0.24 µg/kg bw/day in HMF and MF babies, respectively. Melamine exposure in both groups was below the tolerable daily intake. There were no significant associations between melamine exposure and various features of babies and mothers. As a result, it can be suggested that Turkish babies (aged 0-6 months) are not at risk for high melamine exposure through the diet.

Elevated levels of biomarkers of oxidative stress and renal injury linked to nitrogenous flame retardants exposure in e-waste dismantling site: A case study in China

Nitrogenous flame retardants (NFRs) have aroused worldwide public concern as their nephrotoxic effect. However, knowledge regarding the pathogenesis mechanism of their exposure to induce kidney injury remains largely unknown. In this study, eight NFRs, four oxidative stress biomarkers (OSBs), and one kidney injury biomarker, namely neutrophil gelatinase-associated lipocalin (NGAL), were measured in urine specimens collected from residents living around e-waste disassembly and reference areas, representing two exposure scenarios. Significant higher concentrations of Σ₈NFR (median: 70.6 vs. 33.8 μg/g Cre) and five biomarkers (124 vs. 97.4 μg/g Cre) were found in urines of populations living in e-waste site compared to those in the reference site (p < 0.05). Primary NFRs exhibited significant positive associations with OSBs and NGAL regardless of the population examined, implying that chronic NFRs exposure could induce oxidative stress and kidney damage. By using structure equation model, we found that oxidative stress, particularly DNA and RNA oxidation mediated 16.1% of the total effect of NFRs on NGAL in e-waste related people, but not on the general population. Overall, this study suggests long-term chronic exposure to NFRs can induce oxidative stress and renal injury in humans but the pathogenesis mode may be scenario-specific.

Understanding the Chemical Exposome During Fetal Development and Early Childhood: A Review

Early human life is considered a critical window of susceptibility to external exposures. Infants are exposed to a multitude of environmental factors, collectively referred to as the exposome. The chemical exposome can be summarized as the sum of all xenobiotics that humans are exposed to throughout a lifetime. We review different exposure classes and routes that impact fetal and infant metabolism and the potential toxicological role of mixture effects. We also discuss the progress in human biomonitoring and present possiblemodels for studying maternal-fetal transfer. Data gaps on prenatal and infant exposure to xenobiotic mixtures are identified and include natural biotoxins, in addition to commonly reported synthetic toxicants, to obtain a more holistic assessment of the chemical exposome. We highlight the lack of large-scale studies covering a broad range of xenobiotics. Several recommendations to advance our understanding of the early-life chemical exposome and the subsequent impact on health outcomes are proposed.

The first detection of quaternary ammonium compounds in breast milk: Implications for early-life exposure

BACKGROUND

Quaternary ammonium compounds (QACs), commonly used in cleaning, disinfecting, and personal care products, have recently gained worldwide attention due to the massive use of disinfectants during the COVID-19 pandemic. However, despite extensive use of these chemicals, no studies have focused on the analysis of QACs in human milk, a major route of exposure for infants.

OBJECTIVE

Our objectives were to identify and measure QACs in breast milk and evaluate early-life exposure to this group of compounds for nursing infants.

METHODS

Eighteen QACs, including 6 benzylalkyldimethyl ammonium compounds (BACs, with alkyl chain lengths of C8-C18), 6 dialkyldimethyl ammonium compounds (DDACs, C8-C18), and 6 alkyltrimethyl ammonium compounds (ATMACs, C8-C18), were measured in breast milk samples collected from U.S. mothers. Daily lactational intake was estimated based on the determined concentrations for 0-12 month old nursing infants.

RESULTS

Thirteen of the 18 QACs were detected in breast milk and 7 of them were found in more than half of the samples. The total QAC concentrations (ΣQAC) ranged from 0.33 to 7.4 ng/mL (median 1.5 ng/mL). The most abundant QAC was C14-BAC with a median concentration of 0.45 ng/mL. The highest median ΣQAC estimated daily intake (EDI) was determined for <1-month old infants based on the average (using the median concentration) and high (using the 95th percentile concentration) exposure scenarios (230 and 750 ng/kg body weight/day, respectively).

SIGNIFICANCE

Our findings provide the first evidence of the detection of several QACs in breast milk and identify breastfeeding as an exposure pathway to QACs for nursing infants.

IMPACT STATEMENT

Our findings provide the first evidence of QAC occurrence in breast milk and identify breastfeeding as one of the exposure pathways to QACs for nursing infants.

Exposure to melamine and its derivatives in Chinese adults: The cumulative risk assessment and the effect on routine blood parameters

Melamine (MEL) and its derivatives, ammeline (AMN), ammelide (AMD), cyanuric acid (CYA) are widely existed in environmental media. Animal studies have reported the cumulative risk assessment (CRA) of simultaneous exposure to MEL and its derivatives and explored the associations between exposure and routine blood parameters. Such information is largely unknown in human studies. In this study, we detected the urinary concentrations of MEL and its derivatives in 239 Chinese adults to conduct the CRA by evaluating their hazard quotients (HQ) and hazard Index (HI), and also explored the possible associations between exposure and measured routine blood parameters in study population. The detectable frequencies of MEL, AMN, AMD and CYA were 96.65%, 41.00%, 97.91% and 97.07%, respectively. The median values of creatinine (Cr)-adjusted MEL, AMN, AMD, CYA and the total concentrations of MEL and its derivatives (∑MEL) were 11.41 μg/g Cr, not detected (ND), 2.64 μg/g Cr, 15.30 μg/g Cr, 35.02 μg/g Cr, respectively. There were 9 (3.77%) participants with estimated daily intakes (EDIs) of CYA exceeding the tolerable daily intake (TDI) of 2500 ng/kg bw/day, and 12 (5.02%) participants with HI of ∑MEL exposure exceeding 1 based on the strictest TDI value. Urinary concentrations of MEL and its derivatives were positively associated with specific routine blood parameters, including hematocrit, hemoglobin, mean corpuscular volume, mean corpuscular hemoglobin concentration, mean corpuscular hemoglobin, white blood cell, neutrophil count (P < 0.05). Meanwhile, exposure to MEL and its derivatives increased the risk of red blood cell abnormality (P < 0.05). Our study is the first study to provide evidence-based data on the CRA of exposure to MEL and its derivatives in Chinese adults, and to propose a possible association between such exposure and routine blood parameters in human.

E-waste dismantling-related occupational and routine exposure to melamine and its derivatives: Estimating exposure via dust ingestion and hand-to-mouth contact

Melamine (MEL) and its derivatives are increasingly applied as nitrogenous flame retardants in consumer products. Nevertheless, limited information is available on their environmental occurrence and subsequent human exposure via multiple exposure pathways. In this study, we analysed MEL and its derivatives in dust (indication of the dust ingestion route) and hand wipe samples (indication of the hand-to-mouth route) collected in various microenvironments. The levels of ∑MELs in both dust (median: 24,100 ng/g) and participant hand samples (803 ng/m²) collected in e-waste dismantling workshops were significantly higher than those in samples collected in homes (15,600 ng/g and 196 ng/m², respectively), dormitories (13,100 ng/g and 227 ng/m², respectively) and hotel rooms (11,800 ng/g and 154 ng/m², respectively). Generally, MEL dominated in dust samples collected in e-waste dismantling workshops, whereas cyanuric acid dominated in hand wipe samples. This may occur partly because the latter is an ingredient in disinfection products, which are more frequently employed in daily lives during the COVID-19 pandemic. Exposure assessment suggests that dust ingestion is an important exposure pathway among dismantling workers and the general population, whereas hand-to-mouth contact could not be overlooked in certain populations, such as children and dismantling workers not wear gloves at work.

Elevated emissions of melamine and its derivatives in the indoor environments of typical e-waste recycling facilities and adjacent communities and implications for human exposure

Melamine and its derivatives are used as additives in flame retardants. Moreover, melamine-containing consumables such as laminates, adhesives, glues, and plastics are extensively used in electronic products. Nevertheless, there is no information concerning the identification of melamine and its derivatives during e-waste recycling. In the present study, the occurrence of melamine and three of its derivatives (cyanuric acid, ammelide, and ammeline) was identified for the first time in indoor dust from typical e-waste recycling areas and adjacent rural communities. Urban communities situated about 80 kilometers away were used as a control. The target analytes were detected in almost all the dust samples, which were dominated by melamine and cyanuric acid. The total concentrations of melamine and its derivatives varied among sampling locations in the following order: e-waste workshops (geometric mean: 15,018 ng/g) > urban houses (9060 ng/g) > local rural houses (6204 ng/g) > local streets (201 ng/g). This suggested that e-waste dismantling/recycling activities mainly contributed to the abundant emission of melamine and its derivatives in e-waste dust. Correlation analysis indicated that melamine and its derivatives were similarly applied in electronic products and e-waste recycling resulted in common emissions. The combined toxicity of melamine and its derivatives on human bladder cancer cells was observed. Importantly, Monte Carlo analysis was used to determine that the estimated daily intakes of these chemicals via dust ingestion for occupational e-waste recycling workers were 2.5-9 times higher than the estimated daily intakes for adult residents in both adjacent local communities and urban areas. These results are the first to demonstrate that e-waste dismantling workers are more vulnerable to the exposure risk posed by the presence of melamine and its derivatives in e-waste dust, which deserves more research attention.

Green detection of trace cyanuric acid and free chlorine together via ion chromatography

Chlorinated cyanurates (CCAs) are a type of disinfectants currently used worldwide for fight of Coronavirus. However, CCAs upon dosed into water can release not only free chlorine (FC), a strong disinfectant, but also cyanurate (CYA), a persistent compound potentially harmful to human and environment. Therefore, detecting CYA and FC in water are very important not only for ensuring sufficient disinfection but also for monitoring the impacts of FC and CYA on receiving watershed. However, conventional analytical methods for them are mostly based on colorimetric methods, which have high method detection limits (MDLs) and rely on chemical reactions that are likely sensitive to coexisting chemicals. To overcome these issues, we herein proposed a facile and reaction-free method to detect CYA and FC together in just one run by ion chromatography (IC) equipped with both conductivity and ultraviolet absorbance detectors. The method features obvious advantages over colorimetric methods in being lower MDLs (3.6 μg/L for CYA and 9.0 μg/L for FC), environmental-friendly (i.e., no organic solvent involved), and more resistant to alkaline solution. With this method, trace levels of CYA (i.e., 34-44 μg/L), which were nondetectable by conventional method, were found in two river water samples, implying that the local environment was already polluted by CCAs during the pandemic period. Overall, this study demonstrates a robust tool that may assist better understanding and monitoring the fate and transport of trace CCA derivatives in water.

Suspect screening and untargeted analysis of veterinary drugs in food by LC-HRMS: Application of background exclusion-dependent acquisition for retrospective analysis of unknown xenobiotics

The presence of veterinary drug and pesticide residues in food products pose considerable threats to human health. Monitoring of these residues in food is mainly carried out using targeted analysis by triple quadrupole mass spectrometry. However, these methods are not suitable for suspect screening and untargeted analysis of unknowns. The main objectives of this study were to develop a new high-resolution mass spectrometry (HRMS)-based analytical strategy for retrospective analysis of suspect and unknown xenobiotics and to evaluate its performance in the tentative identification of 48 veterinary drugs as "unknowns" spiked in a pork sample. In the analysis, a newly developed background exclusion data-dependent acquisition (BE-DDA) technique was employed to trigger the product ion (MS/MS) spectral acquisition of the "unknowns", and an in-house precise-and-thorough background-subtraction (PATBS) technique was applied to detect these "unknowns". Results showed that untargeted data mining of the acquired LC-MS dataset by PATBS was able to find all the 48 veterinary drugs and 46 of them were triggered by BE-DDA to generate accurate MS/MS spectra. The dataset of recorded accurate full-scan mass and MS/MS spectra of all the xenobiotics of the test pork sample is defined as the xenobiotics profile. Searching the xenobiotic profile of the test pork sample using mass spectral data of selected veterinary drugs (as suspects) from the mzCloud spectral library led to the correct hits. Searching against the mzCloud spectral library using the mass spectral data of selected individual veterinary drugs (as unknowns) from the xenobiotics profile tentatively confirmed their identities. In contrast, analysis of the same sample using ion intensity-data dependent acquisition only recorded the MS/MS spectra for 34 veterinary drugs. In addition, a data independent acquisition method enabled the acquisition of the fragment spectra for 44 veterinary drugs, but their spectral data displayed only one or a few true product ions of individual analytes of interest along with many fragments from coeluted biological components and background noises. This study demonstrates that this analytical strategy has a potential to become a practical tool for the retrospective suspect screening and untargeted analysis of unknown xenobiotics in a biological sample such as veterinary drugs and pesticides in food products.

Endocrine-Disrupting Chemicals and Child Health

While definitions vary, endocrine-disrupting chemicals (EDCs) have two fundamental features: their disruption of hormone function and their contribution to disease and disability. The unique vulnerability of children to low-level EDC exposures has eroded the notion that only the dose makes the thing a poison, requiring a paradigm shift in scientific and policy practice. In this review, we discuss the unique vulnerability of children as early as fetal life and provide an overview of epidemiological studies on programming effects of EDCs on neuronal, metabolic, and immune pathways as well as on endocrine, reproductive, and renal systems. Building on this accumulating evidence, we dispel and address existing myths about the health effects of EDCs with examples from child health research. Finally, we provide a list of effective actions to reduce exposure, and subsequent harm that are applicable to individuals, communities, and policy-makers. Expected final online publication date for the Annual Review of Pharmacology and Toxicology, Volume 62 is January 2022. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.

Per- and Polyfluoroalkyl Substances (PFAS) in Breast Milk: Concerning Trends for Current-Use PFAS

This is the first study in the last 15 years to analyze per- and polyfluoroalkyl substances (PFAS) in breast milk collected from mothers (n = 50) in the United States, and our findings indicate that both legacy and current-use PFAS now contaminate breast milk, exposing nursing infants. Breast milk was analyzed for 39 PFAS, including 9 short-chain and 30 long-chain compounds, and 16 of these PFAS were detected in 4-100% of the samples. The ∑PFAS concentration in breast milk ranged from 52.0 to 1850 pg/mL with a median concentration of 121 pg/mL. Perfluorooctanesulfonic acid (PFOS) and perfluorooctanoic acid (PFOA) were the most abundant PFAS in these samples (medians 30.4 and 13.9 pg/mL, respectively). Two short-chain PFAS, including perfluoro-n-hexanoic acid (PFHxA, C6) and perfluoro-n-heptanoic acid (PFHpA, C7), were detected in most of the samples with median concentrations of 9.69 and 6.10 pg/mL, respectively. Analysis of the available breast milk PFAS data from around the world over the period of 1996-2019 showed that while the levels of the phased-out PFOS and PFOA have been declining with halving times of 8.1 and 17 years, respectively, the detection frequencies of current-use short-chain PFAS have been increasing with a doubling time of 4.1 years.

The National Children's Study Archive Model: A 3-Tier Framework for Dissemination of Data and Specimens for General Use and Secondary Analysis

The National Children's Study (NCS) Archive was created as a repository of samples, data, and information from the NCS Vanguard Study-a longitudinal pregnancy and birth cohort evaluating approaches to study influence of environmental exposures on child health and development-to provide qualified researchers with access to NCS materials for use in secondary research. The National Children's Study Archive (NCSA) model is a 3-tiered access model designed to make the wealth of information and materials gathered during the NCS Vanguard Study available at a user appropriate level. The NCSA model was developed as a 3-tier framework, for users of varying access levels, providing intuitive data exploration and visualization tools, an end-to-end data and sample request management system, and a restricted portal for participant-level data access with a team of experts available to assist users. This platform provides a model to accelerate transformation of information and materials from existing studies into new scientific discoveries. Trial Registration: ClinicalTrials.gov Identifier: NCT00852904 (first posted February 27, 2009).

Nationwide Biomonitoring of Neonicotinoid Insecticides in Breast Milk and Health Risk Assessment to Nursing Infants in the Chinese Population

Presently, the potential health risks of neonicotinoid insecticides (neonics) are now receiving much attention, but no data regarding the exposure of infants to neonics via human breast milk intake have been reported. In this study, a nationwide survey was conducted during the period of 2017-2019, wherein 97 pooled breast milk samples were collected from 3570 lactating women of 23 provinces in China. Nationally, acetamiprid-N-desmethyl was the most predominant compound, accounting for 61.2% of the total amount of neonics, followed by imidacloprid (15.6%). The concentration of the sum of acetamiprid and its metabolite acetamiprid-N-desmethyl in breast milk was positively correlated with corresponding dietary exposure, while no statistically significant association between the other neonic levels in breast milk and dietary exposure was found. The cumulative daily intakes of neonics (9.40-249 ng kg^-1 of body weight day^-1) were estimated for breastfed infants, indicating a minuscule risk to Chinese infants from neonic exposure via breastfeeding.

Are Melamine and Its Derivatives the Alternatives for Per- and Polyfluoroalkyl Substance (PFAS) Fabric Treatments in Infant Clothes?

Per- and polyfluoroalkyl substances (PFAS) and melamine (MEL)-based compounds are used in textile finishing as grease, stain, and water repellents. Here, we investigated the occurrence of a large suite of PFAS and MEL compounds in 86 infant clothing items. The ∑MEL concentrations ranged from below the method detection limit to 250,000 ng/g with a median concentration of 78.2 ng/g, significantly higher (p < 0.05) than the ∑PFAS levels (1.22-203 ng/g; median 3.62 ng/g). MEL and its derivatives were most abundant in nylon clothes (median 32,800 ng/g), followed by organic cotton (median 6120 ng/g). In a simulated laundering experiment, the ∑MEL concentrations in clothing decreased on an average by ∼60 and 90% when washed in cool (20 °C) and warm (50 °C) water, respectively. This removal rate increased to 97% when the samples were washed with a detergent. The estimated daily intakes of MEL and PFAS through dermal absorption from nylon clothes were three orders of magnitude higher than those from the non-nylon clothes and decreased by more than half for washed clothes. Our findings demonstrate that MEL-based compounds are abundant in infant clothing and suggest that this group of compounds could be used as potential PFAS replacements in textile finishing.

Assessment of imidacloprid related exposure using imidacloprid-olefin and desnitro-imidacloprid: Neonicotinoid insecticides in human urine in Wuhan, China

While neonicotinoid insecticides (NNIs) have been widely used worldwide, limited studies have measured specific metabolites of imidacloprid (IMI, the most commonly used NNI) in human urine. To better understand human exposure to NNIs, 10 parent compounds, and 6 of their metabolites were analyzed in 408 urine samples collected from 129 healthy adults in Wuhan, Central China, during autumn and winter of 2018. These specimens included repeated urine samples taken in 3 d from 75 volunteers. The urinary concentrations of desnitro-imidacloprid (DN-IMI), imidacloprid-olefin (IMI-olefin), and desmethyl-acetamiprid (DM-ACE) were higher (4-40 times) than those of their parent compounds (IMI and acetamiprid, ACE). DN-IMI and IMI-olefin accounted for 92% of the urinary Σ₃IMI (the sum of IMI and its specific metabolites measured). Positive correlations (r) were observed between DN-IMI and IMI (0.50), IMI-olefin and IMI (0.75), and DM-ACE and ACE (0.53). Good to excellent inter-day reliabilities (unadjusted intraclass correlation coefficients) were observed for IMI-olefin (0.61) and DM-ACE (0.81), while moderate inter-day reliability was observed for DN-IMI (0.43). The urinary NNI concentrations were significantly higher in autumn than in winter, and higher in urban areas than in rural areas, while no significant gender or age-related differences were observed. To our knowledge, this is the first report on DN-IMI and IMI-olefin in human urine.

Exposure to melamine and its derivatives in childcare facilities

Melamine (MEL) and its derivatives are widely used in many consumer products, including furniture, kitchenware, and plastics. However, very limited knowledge exists on human exposure to MEL and its derivatives, especially in the indoor environment. Here, we determined the occurrence and distribution of 11 MEL derivatives in childcare facilities and estimated children's exposure through dust ingestion and dermal absorption. We analyzed dust and samples of nap mats, a commonly used item in many childcares, from eight facilities located in the United States. Eight MEL-based compounds were detected in dust, and total MEL concentrations ranged from 429 to 117,000 ng/g. The most abundant compounds found in the dust samples were MEL, cyanuric acid (CYA), ammeline (AMN), and ammelide (AMD), with median concentrations of 1620, 585, 1060, and 299 ng/g, respectively. MEL, CYA, AMN and 2,4,6-tris[bis(methoxymethyl)amino]-1,3,5-triazine (TBMMAT) were also detected in nap mats with median concentrations of 45.6, 19.8, 1510 and 2.5 ng/g, respectively. ΣMEL concentrations in mat covers (median 709 ng/g) were significantly higher than those in mat foam (median 15.1 ng/g). Estimated daily intakes (EDIs) of MEL and its derivatives via dust ingestion were two orders of magnitude higher than the EDIs through dermal absorption, but both were below the established tolerable daily intake levels. This is the first report on exposure to MEL and its derivatives in the childcare environment.

Determination of melamine and its derivatives in textiles and infant clothing purchased in the United States

Melamine-based resins are used extensively in fabrics to impart fire and heat resistance as well as wrinkle-free properties. Little is known, however, regarding the occurrence of melamine and its derivatives in textiles. In this study, concentrations of melamine, ammeline, ammelide, and cyanuric acid were determined in 77 textile samples and infant clothing purchased from Albany, New York, USA. All textile samples contained one or more target analytes, at concentration ranges of 1.19-81,800, 3.21-17,800, <1.20-25,700, and <0.50-550 ng/g for melamine, cyanuric acid, ammeline, and ammelide, respectively. Melamine was the predominant compound, accounting for 52% of the total concentrations of four analytes (i.e., ∑melamines). Significant positive correlations were found between the concentrations of melamine and its three derivatives (0.347 < r < 0.862, p < .01). The concentrations of ∑melamines were significantly higher in cotton fabrics (mean: 10,500 ng/g) and cotton clothes (10,200 ng/g) than in synthetic fabrics (1,380 ng/g) and socks (40.0 ng/g) (p < .01). Simulated laundry experiments suggested that a single round of washing with water removed 76-90% of melamine from clothing. The calculated dermal exposure doses of melamine and cyanuric acid were three to four orders of magnitude below the reference value. This study provides the first evidence of the occurrence of melamine derivatives in textiles and clothing purchased in the United States. CAPSULE: Melamine and cyanuric acid are widely distributed in textiles and infant clothing collected from the United States.

Government regulation and consumer evaluation after dairy products scandal in China

With the continuous expansion of the global dairy trade market, the quality and safety of the Chinese dairy market have a wide and far-reaching impact on the world. Based on the development of the dairy scandal in the past few years in China, this study illustrates the serious damage of melamine on human health and the negative impact on the dairy industry in China.

This study shows that the lack of effective government regulations is a key reason for dairy market failure. Consumers are lacking confidence in the quality of Chinese dairy products and the government's market regulations. The Chinese dairy market will continue to rely on imported dairy products. By analyzing the typical cases of the dairy market in China, this study aims to provide a guide for dairy industries in other countries.

Occurrence and distribution of melamine and its derivatives in surface water, drinking water, precipitation, wastewater, and swimming pool water

The extensive use of melamine and its three derivatives (i.e., ammeline, ammelide, and cyanuric acid) resulted in their widespread occurrence in the environment. Nevertheless, limited information is available on their distribution in the aquatic environment. In this study, concentrations and profiles of melamine and its derivatives were determined in 223 water samples, comprising river water, lake water, seawater, tap water, bottled water, rain water, wastewater, and swimming pool water, collected from New York State, USA. The sum concentrations of melamine and its derivatives (∑₄MELs) decreased in the following order: swimming pool water (median: 1.5 × 10⁷ ng/L) ≫ wastewater (1240) > precipitation (739) > tap water (512) > river water (370) > lake water (347) > seawater (186) > bottled water (98). Cyanuric acid was the major compound, accounting for 60-100% of ∑₄MELs concentrations in swimming pool water, wastewater, precipitation, tap water, seawater, and bottled water, whereas melamine dominated in river and lake water (54-64% of ∑₄MELs). Significant positive correlations (0.499 < R < 0.703, p < 0.002) were found between the concentrations of melamine and atrazine (a triazine herbicide) in surface waters. The geographic distribution in the concentrations of ∑₄MELs in river, lake, and tap water corresponded with the degree of urbanization, suggesting that human activities contribute to the sources melamine and cyanuric acid in the aquatic environments. A preliminary hazard assessment of melamine and cyanuric acid in waters suggested that their ecological or human health risks were minimal. This is the first study to document the occurrence and spatial distribution of melamine and its derivatives in waters from the United States.

An assessment of melamine exposure in Shanghai adults and its association with food consumption

Melamine is widely used to make household products including plates, cups, and large-scale industrial plastic products. Studies have shown the nephrotoxicity of melamine. However, little is known about urinary melamine concentration in adults and its association with the consumption of foods, other than milk products. In this study, we measured the urinary melamine concentration of 908 Shanghai adults and calculated the estimated daily intake (EDI) and hazard quotient accordingly. We also used a 24 h (24-hr) recall survey to identify possible risk foods associated with melamine exposure. Melamine was detectable in over 85% of the urine samples and had a median concentration of 2.524 μg/g. There were 22 participants who had EDIs exceeding the tolerable daily intake (TDI) of 3150 ng/kg bw/day, the strictest reference dose in administration by far. Melamine concentration in urine was positively associated with the 24-hr recall consumption of rice, fruits, beef, mutton, processed meats, and eggs, but no other food categories. Our study provides evidence-based data on the melamine exposure level in adults from Shanghai, China, and some possible associations with food intake.

Presence of melamine in human milk and the evaluation of the effects on mother–infant pairs in a cohort study

Melamine contamination is a recent public health problem emerging globally. Present study aimed to detect the rate of melamine presence in human milk in a cohort study and to evaluate any possible differences in maternal–infant pair characteristics such as breastfeeding status, crying and sleep problems of infants, maternal postpartum depression, maternal–infant bonding, infant and maternal anthropometry, and maternal complete blood count caused by the melamine exposure. Mothers of infants born in Şanlıurfa were invited to participate in ‘Urfa Child Cohort Survey’. Overall, two breast milk samples were taken between 5 days and 15 days postpartum and between 4 weeks and 10 weeks. Randox Food’s InfiniPlex array was used to analyse the presence of melamine. Melamine was detected in 32.2% and 24.4% of the first and the second milk samples; 16.7% of mothers had two positive samples. z Scores for birth weight and z scores for height for age were detected to be significantly lower in cases with two positive samples compared to cases with negative samples. Mean maternal white blood cells counts were found to be lower in cases with repeated melamine contact. Melamine might have a detrimental effect on birth weight, infant height and maternal blood count. Further studies should be done to detect environmental contamination in different regions and countries.

Organophosphorus Flame Retardants and Plasticizers in Breast Milk from the United States

Organophosphate esters (OPEs) are used in consumer products as flame retardants and plasticizers. Little is known, however, about the occurrence and profiles of OPEs in human milk. In this study, 14 OPEs were measured in 100 breast milk samples collected from the United States during the period of 2009-2012, using high-performance liquid chromatography and tandem mass spectrometry. The sum concentrations of 14 OPEs in human milk ranged from 0.670 to 7.83 ng/mL, with a mean value of 3.61 ng/mL. The highest mean concentration was found for tris-2-butoxyethyl phosphate (TBOEP, 1.44 ± 0.789 ng/mL), followed by tri-iso-butyl phosphate (TIBP, 0.569 ± 0.272 ng/mL) and tri-n-butyl phosphate (TNBP, 0.539 ± 0.265 ng/mL), which were the dominant OPEs found in breast milk at detection frequencies of >80%. No significant differences were observed between various maternal/infant characteristics and OPE concentrations (p > 0.05), except for TBOEP, for which the median concentrations in Hispanic mothers (0.765 ng/mL) were 2 times lower than those in non-Hispanic mothers (1.48 ng/mL) (p < 0.05). On the basis of the recommended daily milk ingestion rate, the average and the highest daily intakes of total OPEs were calculated to be in the range of 300-542 and 504-911 ng (kg of body weight)^-1 day^-1, respectively. The estimated daily intakes of OPEs did not exceed the current reference doses. Our study establishes baseline data for OPE exposure in breast-fed American children.