LInking EDCs in maternal Nutrition to Child health (LINC study) - protocol for prospective cohort to study early life exposure to environmental chemicals and child health

The questionnaire design process in the European Human Biomonitoring Initiative (HBM4EU)

BACKGROUND

Designing questionnaires is a key point of epidemiological studies assessing human exposure to chemicals. The lack of validated questionnaires can lead to the use of previously developed and sub-optimally adapted questionnaires, which may result in information biases that affect the study's validity. On this ground, a multidisciplinary group of researchers developed a series of tools to support data collection within the HBM4EU initiative. The objective of this paper is to share the process of developing HBM4EU questionnaires, as well as to provide researchers with harmonized procedures that could help them to design future questionnaires to assess environmental exposures.

METHODS

In the frame of the work package on survey design and fieldwork of the HBM4EU, researchers carried out procedures necessary for the development of quality questionnaires and related data collection tools. These procedures consisted of a systematic search to identify questionnaires used in previous human biomonitoring (HBM) studies, as well as the development of a checklist and evaluation sheet to assess the questionnaires identified. The results of these evaluations were taken into consideration for the development of the final questionnaires.

RESULTS

The main points covered by each of the sections included in HBM4EU questionnaires are described and discussed in detail. Additional tools developed for data collection in the HBM4EU (e.g. non-responder questionnaire, satisfaction questionnaire, matrix-specific questionnaire) are also addressed. Special attention is paid to the limitations faced and hurdles overcome during the process of questionnaire development.

CONCLUSIONS

Designing questionnaires for use in HBM studies requires substantial effort by a multidisciplinary team to guarantee that the quality of the information collected meets the study's objectives. The process of questionnaire development described herein will contribute to improve the harmonization of HBM studies within the social and environmental context of the EU countries.

Organophosphate ester metabolites in human breast milk determined by online solid phase extraction coupled to high pressure liquid chromatography tandem mass spectrometry

The analysis of metabolites of organophosphate esters (OPEs) in human breast milk is essential to evaluate OPE and OPE metabolite exposure of newborns. In the current study, an analytical method which only needs a small amount of breast milk (100 μl) was developed and validated for six diester metabolites and three hydroxylated metabolites applying salt-induced liquid-liquid extraction (SI-LLE) and dispersive solid phase extraction (d-SPE) for sample preparation and online solid phase extraction coupled to high pressure chromatography tandem mass spectrometry (online-SPE-HPLC-MS/MS) for quantitative measurement. The final method consisted of an extraction with formic acid (FA)/acetonitrile (1:200, v/v) and a cleanup with C18 d-SPE. The final extracts were trapped on a C18 cartridge with application of a wash step of 2 ml 0.1% FA milli-Q/methanol (98:2, v/v). Method detection limits (MDLs) ranging from 21.7 ng/l for BBOEHEP to 500 ng/l for BCIPP and average recoveries ranging from 58% for 5-OH-EHDPHP to 120% for BCIPP were achieved. Thirty-three breast milk samples from the LINC (Linking EDCs in maternal Nutrition to Child health) cohort collected in three distinct areas in The Netherlands were analyzed using the validated method. BCEP, BCIPP, BCIPHPP, BDCIPP, and 5-OH-EHDPHP were not detected in any of the samples, while BBOEP was the most frequently detected metabolite with a concentration range of <MDL to l.47 ng/ml, followed by DPhP and BBOEHEP, detected in ranges of <MDL to 0.09 and <MDL to 0.027 ng/ml. The results indicated that OPEs entering the human body are only to a limited extent excreted via breast milk.

Toddler behavior, the home environment, and flame retardant exposure

Toddlers are at increased risk of dust ingestion and subsequently flame retardant (FR) exposure because they often play close to the floor and mouth hands and objects. Exposure to some FRs have been associated to endocrine disruption and neurodevelopmental disorders. Previous research has shown higher FR concentrations in toddlers' serum and urine, but which toddler-behaviors influence exposure levels remains to be determined. We investigated how toddler-behaviors are associated to FRs in hand wipes (HWs) and saliva. Fifty 8-18 month-old children from the Linking EDCs in maternal Nutrition to Child health study, were visited at home. The child's behavior was observed and assessed using a questionnaire. Hand-to-object behavior frequency was associated with HW tris(chloroethyl) phosphate (TCEP), tris(1,3-dichloroisopropyl) phosphate (TDCIPP), tris(phenyl) phosphate, tris(methylphenyl) phosphate, and resorcinol bis(diphenyl phosphate) levels above the detection limit. Children playing with electronics multiple times per week had higher TDCIPP HW levels compared to children playing with electronics once per month or never (p = 0.032 and p = 0.046). Frequent mouth-to-object and frequent mouthing a pacifier were associated with lower TDCIPP (p = 0.019) and tris(2-chloroisopropyl) phosphate (TCIPP) HW levels, respectively (p = 0.002-0.019). Exposure estimates based on hand-to-mouth behavior did not exceed the available reference doses. This is the first study investigating toddler-behavior in relation to FR hand loadings. Although a range of behaviors was investigated, only a few showed a relation with FR HW levels, suggesting that toddler-behavior might not alone be responsible for the elevated FR levels in children. It is therefore important to explore other pathways including dermal absorption and inhalation.

Predictors with regard to ingestion, inhalation and dermal absorption of estimated phthalate daily intakes in pregnant women: The Barwon infant study

Human exposure to phthalate chemicals, used in consumer product plastics, occurs throughout the day. Phthalate levels in pregnant women are associated with offspring health effects including obesity and neurodevelopmental problems. Knowledge of predictors of exposure is necessary in order to effectively reduce phthalate exposure. The present study aims to identify predictors of phthalate levels in Australian pregnant women from the Barwon Infant study birth cohort. Maternal urine samples from 841 women were analyzed for phthalate metabolites. Maternal diet and food preparation practices, use of volatile household products, household characteristics and personal care product use were assessed with questionnaires. All maternal urine contained phthalate metabolites. Maternal prenatal high-fat milk consumption was associated with higher benzyl butyl phthalate (BBzP) (p < 0.001), and bis(2-ethylhexyl) phthalate (DEHP) (p = 0.0023). Higher phthalate levels were associated with consumption of tinned food (fish and tomatoes). Diethyl phthalate (DEP) levels were significantly higher when women reported using air freshener (35% increase, p = 0.01), aerosols (40% increase, p = 0.005), hair treatment chemicals (28% increase, p = 0.031), and chlorine (34% increase, p = 0.009) compared to no use. Maternal phthalate levels did not vary by reported plastic avoidance during pregnancy. The study showed that phthalate exposure is ubiquitous and increased by multiple factors. Future intervention studies to reduce phthalate levels among pregnant women will need to take into account the variety of sources identified in this study.

Electronics, interior decoration and cleaning patterns affect flame retardant levels in the dust from Dutch residences

Consumer products such as furniture foam and electronic device casings are treated with flame retardant chemicals (FRs) to prevent the spread of fire. Many FRs are able to leach out of a product and end up in house dust. FRs in house dust can be taken up by humans through inhalation, ingestion or dermal adsorption. This study aims to identify factors in the home environment that are associated with FR levels in house dust. House dust and a wide range of data on characteristics of electronics, including age and use, interior decoration, domestic house and cleaning patterns, were collected from 50 households in the Netherlands. Decabromodiphenyl ether (BDE209) and several organophosphate flame retardants were measured in dust at detection percentages ranging from 58 to 94%, with median concentrations ranging from 32 ng/g (resorcinol-bis(diphenyl)phosphate (PBDPP)) to 825 ng/g (tris(chloropropyl)phosphate (TCIPP)). For the first time, age, hours of operation and use of the standby function of electronic devices were found to affect FR levels in dust. We found that if the total number of electronic devices purchased before 2008 increased by 1 device, BDE209 levels in house dust significantly increased by 66%. In addition, house dust from homes with carpeted floors was significantly associated with a 70-80% lower concentration of several FRs compared to homes with smooth floors (e.g., laminate). Less frequent vacuum cleaning and dusting were significantly associated with 41 to 88% higher concentrations of several FRs in dust. These associations suggest that actions such as frequent vacuum cleaning and dusting as well as different FR regulations for electronic devices affect indoor exposure levels.

Legacy and alternative halogenated flame retardants in human milk in Europe: Implications for children's health

In this study, 10 polybrominated diphenyl ethers (PBDEs) and 19 alternative halogenated flame retardants (AFRs) were determined in >450 human milk samples across three European countries, representing northern, western and eastern Europe. This study provides first insights into the occurrence of selected AFRs in mother milk samples and compares them among three European countries. Sums of median concentrations of the most frequently detected PBDEs were 2.16, 0.88 and 0.45ngg^-1 lipid weight (lw) in Norway, the Netherlands and Slovakia, respectively. The sum of the concentrations of AFRs ranged from 0.14 to 0.25ngg^-1lw in all countries, which was 2 to 15 times less compared to Σ₇PBDEs. The Penta-BDE replacement, bis(2-ethylhexyl) tetrabromophthalate, BEH-TEBP, was present at the greatest concentrations of any of the AFRs and in some samples exceeded concentrations of BDE 47 and BDE 153. Four AFRs including bromobenzenes (hexabromobenzene, pentabromobenzene, pentabromotoluene) and another Penta-BDE replacement (2-ethylhexyl-2,3,4,5-tetrabromobenzoate, EH-TBB) were detected in >42% of all human milk samples. Because of the potential developmental neurotoxicity of the halogenated flame retardants, infant dietary intakes via breastfeeding were estimated; in four cases the intakes of BDE 47 exceeded the reference dose indicating that the present concentrations may pose a risk for children.

Brominated and organophosphorus flame retardants in body wipes and house dust, and an estimation of house dust hand-loadings in Dutch toddlers

Children generally have higher Flame Retardant (FR) concentrations in serum compared to other age groups. Toddler behavior enhances direct contact with house dust since their frequent presence proximate to the floor, and their mouthing behavior. This study aimed to thoroughly investigate FR levels in body wipes of toddlers 8-18 months old) and in indoor dust using a noninvasive sampling technique. In this cross-sectional study, body wipes from hands, mouth and back, and indoor household dust samples were collected in twenty-one families and analyzed for one brominated- and seven organophosphorus FRs (polybrominated diphenyl ether 209 (BDE209), tris(2-chloroisopropyl) phosphate (TCIPP), tris(chloroethyl) phosphate (TCEP), tris(1,3-dichloroisopropyl) phosphate (TDCIPP), tris(phenyl) phosphate (TPHP), tris(methylphenyl) phosphate (TMPP), resorcinol bis(diphenyl phosphate) and bisphenol A bis(diphenyl phosphate)). Accelerated solvent extraction was used for extraction and the extract was measured with liquid chromatography combined with mass spectrometry. Non-parametric correlation analyses were performed to assess associations. All FRs were detected in body- and indoor dust samples (median range: 1.0ng/hand wipe (BDE209) to 65ng/hand wipe (TCIPP)) and were mostly correlated with each other. We estimated that approximately 260mg dust (range 50-880mg) accumulated on toddler's hands per day. Hand-to-mouth frequency was negatively associated with FR levels in wipes (τ = -0.38, p = 0.04). With increasing age FR concentrations (BDE209, TCEP, TDCIPP, TPHP and TMPP) on hands decreased significantly (p = 0.01-0.03). Girls had significantly less FRs (TCEP, TCIPP, TPHP and TMPP) on the hands (p = 0.01-0.03) than boys. This is to the best of the authors' knowledge the first study in Europe that measured brominated- as well as organophosphorus FRs in several types of body wipes from toddlers and that estimated the amount of house dust that accumulates on toddler's hands.

Developmental neurotoxicants in human milk: Comparison of levels and intakes in three European countries

Developmental neurotoxicants (DNTs), such as methylmercury (MeHg), polychlorinated biphenyls (PCBs) and selected organochlorine pesticides (OCPs), have gained increasing interest recently due to their possible relation to developmental disorders in children, which are increasing worldwide. We analyzed levels of 14 developmental neurotoxicants in human milk samples from Slovakia (n=37), the Netherlands (n=120) and Norway (n=388). Positive identification for most target analytes was >95% in all samples. In all three countries MeHg was measured for the first time in mother milk. The highest MeHg levels were observed in Norway (39pgg^-1 ww) with the highest fish consumption. Levels of indicator PCBs (iPCBs, sum of PCB 28, 52, 101, 138, 153 and 180), HCB and DDE+DDT were 2-4 times higher in Slovakia compared to the Netherlands or Norway. The levels of MeHg and organochlorine compounds were used for calculations of weekly or daily intakes (top-down approach) by means of pharmacokinetic modeling. The intakes ranged from 0.014 to 0.142μgkg_bw^-1week^-1 for MeHg and from 0.043 to 17.4ngkg_bw^-1day^-1 for organochlorine compounds in all three countries. Intakes of iPCBs exceeded a tolerable daily intake of 10ngkg_bw^-1day^-1 in 16% of the Slovak participants. The top-down estimates were compared with bottom-up intakes based on national dietary estimates and the results showed good consistency between both approaches, with the bottom-up intakes exceeding the top-down by a factor of maximum 3.8 for iPCBs in the Netherlands and 3.9 for HCB in Slovakia. This confirms that food consumption in all three countries represents the dominant pathway of exposure to these developmental neurotoxicants.