Table 1 Description of exposure assessment in the birth cohorts by exposure topic

Outdoor air pollution

27

·Many cohorts assessed outdoor air pollution exposure (27 cohorts).

·Air pollution modeling is becoming increasingly the method of choice: land-use regression modeling (18 cohorts) and dispersion modeling (10 cohorts).

·Sixteen cohorts are currently participating in the collaborative EU-funded ESCAPE project that adds land-use regression modeling of nitrogen oxides, particulate matter, soot and particle composition to existing cohort studies using a standardized protocol.

·Most cohorts currently have data on exposure during pregnancy and/or early life.

Water contamination

13

·Disinfection by-products were studied most.

·Exposure assessment usually by means of a combination of questionnaires and individual measurements or routinely collected measurement data (8 cohorts).

·Validation by means of biomonitoring in a small number of subjects (3 cohorts).

·Most studies assessed exposure during pregnancy.

Allergens & microbial agents

27

·Exposure to cat and dog allergen was assessed by means of questionnaires in all cohorts and by means of measurements in house dust samples in 9 and 4 cohorts, respectively.

·Mite allergen levels were measured in settled house dust samples in 10 cohorts.

·Mold exposure was mainly assessed by means of questionnaires.

·Exposure was assessed during infancy and/or early childhood in most studies.

Metals

20

·Most cohorts have analyzed the effects of low-level environmental exposure to mercury (Hg; 15 cohorts) and lead (Pb; 16 cohorts); little attention to other metals.

·Exposure was mainly assessed by means of biomonitoring. Five cohorts used questionnaires, two of them in addition to biomonitoring,

·There are well-standardized protocols for most of the metals.

·Inductively coupled plasma mass spectrometry (ICP-MS) and atomic absorption spectroscopy (AAS) were used most.

·Most measurements were performed in cord blood; other non-invasive matrices such as hair and urine are gaining attention.

Pesticides ^a

18

·Many studies assessed household use (16 cohorts); and occupational exposure (13 cohorts), fewer cohorts assessed dietary exposure (6 cohorts) or residence proximity to crops (2 cohorts).

·Exposures via household use, occupational exposure and diet, were mainly assessed by means of questionnaires.

Persistent organic pollutants

19

·Exposure assessment by means of high performance liquid chromatography (HPLC) measurements in biological samples with adjustment for lipid content.

·Variation between studies with regard to sampling medium, timing of sample collection and lipid adjustment.

Most data available for polychlorinated biphenyl (PCB) and dichlorodiphenyltrichloroethane (DDT).

Other chemical exposures ^b

17

·Few cohorts have measured these contaminants (13 cohorts), but this is a rapidly developing field and more cohorts are planning to assess exposure to other chemicals (7 cohorts).

·Exposure was mainly assessed by means of biomonitoring.

There is heterogeneity with regard to the type of biological media used and the timing of the exposure measurement.

Radiation

12

Ionizing radiation

·Mainly assessed by questionnaire: maternal occupational exposures (3 cohorts), prenatal medical ionizing radiation exposures (6 cohorts); 2 cohorts currently plan to ask questions about medical radiation exposures in children.

·1 cohort is planning to assess residential radon exposure using geographical methods.

·No standardized questionnaires or protocols in this field.

Ultraviolet (UV)

·Only six cohorts are collecting UV-related data through questionnaire questions on sunburn in children, use of sun beds during pregnancy, and time spent outdoors.

·None of the cohorts collect data on maternal and child skin type, sunscreen use, or clothing.

·Standard questionnaires are not available.

Non-ionizing radiation

·Very few cohorts assess exposure to non-ionizing radiation: 2 cohorts include occupational electromagnetic field (EMF) exposure in their questionnaires, 2 cohorts assess extreme low frequency (ELF) exposure to overhead high-voltage power lines through geographical information from electricity companies, 2 cohorts include questions about mobile phone use of the mother during pregnancy and 4 on children’s mobile phone use.

·A few cohorts have started using base-station maps combined with information from home appliances and personal radio frequency (RF) exposimeters, in order to estimate whole body RF/ELF-EMF exposure.

·There are no standardized or validated questionnaires, models or protocols in use at this moment.

Smoking and second hand tobacco smoke

37

·All cohorts have information about exposure during pregnancy and 29 cohorts in addition assessed exposure at different periods during infancy and childhood.

Assessment mainly by questionnaire; cotinine measurements in biological samples (mainly urine) in 14 cohorts.

Noise

14

·All cohorts used questionnaire assessments, mainly about noise annoyance.

·5 cohorts used noise propagation modeling or noise maps.

·Traffic is the source of noise that has been studied most.

·Most cohorts assessed exposure during pregnancy.

Occupational exposures

33

·All cohorts have information on maternal occupation and most cohorts (n=26) have information on paternal occupation for at least one point in time.

·Data mainly collected by means of questionnaires (most often job title; sometimes checklist occupation or occupational exposures).

·Coding of maternal job title (n=17) or use of Job Exposure Matrices (JEM) (n=8) planned/done in a number of studies.