35 39 In agreement with other studies of Nigerian CSWs, 17 all participants were aware that unprotected intercourse with clients was their main exposure risk factor for STI/HIV.
We also examined the effects of interaction between the calendar year and other potential risk factors on the main outcome by communities using the chunk test, followed by a backward elimination process for the full model, which included main exposure, potential risk factors and all interaction products.
We first summarize the childhood lead exposure situation in France and related information on the main exposure media and risk factors.
Six main groups of exposure factors including dietary intake and behaviours, physical activity and sedentary behaviours, family social and physical environment, school environment, socioeconomic status and parental characteristics were measured.
Six main groups of exposure factors were measured: Dietary intake and diet behaviours were assessed using a validated Youth Food Frequency Questionnaire, 16 which allowed the study participants to be ranked by levels of food energy and fat intake and categories of different diet patterns, for example, frequency of fast food, snacks or soft drink consumption.
Multicollinearity of season of delivery and the main exposure was quite low (variance inflation factor of the involved variables < 3).
We evaluated regression models including (1) only the main exposure variables conditional on the matching factors; (2) also smoking, body mass index, and average visit frequency; and (3) the exposure variables and whichever potential confounders were significantly associated with each cancer.
Main exposure measure Exposure to vascular endothelial growth factor inhibiting drugs identified within 180 days before the index date.
Secondly, we took into consideration a large number of potential confounding factors of the association between the main exposure variables (DLCs, DL-PCBs) and QUS parameters.
