Thesis: "Teneurs en métaux des enfants en Afghanistan: Caractérisation et conséquences cognitives en lien avec les situations socio-économiques et environnementales" (Metal contents in children in Afghanistan: Characterisation and cognitive consequences in relation to socio-economic and environmental situations).

## Thesis defense of Abdullah SHINWARI
**Summary
The succession of wars in Afghanistan over the last 50 years has led to lasting political and administrative instability, which has had repercussions on the health of the population. The population is affected by environmental and nutritional problems such as unsafe drinking water, soil and air pollution linked to the unregulated use of toxic substances in agriculture and industry, and poor waste management. Given this situation, we can expect high risks of chemical and biological contamination, for which there is no monitoring network in Afghanistan. To the best of our knowledge, there are no published studies on the extent of such contamination, particularly of metals whose toxicity in children can lead to cognitive delays (as in the case of lead, for example). To remedy this lack of information, we set up a cross-sectional study to identify metal intoxication in school-age children in Afghanistan in relation to living conditions (socio-economic and environmental), anthropometric data (age, age- and height-corrected body mass index BMIzscores), and cognitive performance specific to these children. This cross-sectional study was carried out in 5 schools in the second largest city in Afghanistan, Jalalabad, on 248 children aged between 6 and 15, mostly boys (70.2%) from 4 public schools and one state school. Anthropometric measurements (weight, height) were taken on site, and blood samples were taken from all the pupils. Pupils were given a cognitive test, Tony-1, and completed a socio-economic questionnaire (PPI People Poverty Index). Other variables were recorded, such as living conditions (proximity to traffic arteries and factories), water supply, mother tongue and use of cosmetics. The average age of the pupils was 11.7 years (±2.0 years) with an average IQ of 83.8 (±12.6) on the Tony-1 scale. A total of 14.9% of the pupils were overweight, 31.5% lived below the poverty line defined at 1.25 US dollars, 53.6% received their water supply from the urban network, 66.9% lived near major roads and 30.6% used surma (cosmetics contaminated with metals). The median levels of metals in the blood of the pupils (μg per dl except for Fe in mg per dl) are for the essential elements Cu (85.3±15.3), Zn (3426±1777), Mg (3993±722) Fe (43.4±5.44) and for potentially toxic metals Mn (7.26±2.34), V (0.57±0.31), Cd (0.04±0.02), As (0.27±0.11), Ti (3.77±1.40), U (0.02±0.01), Pb (6.89±1.97). When compared with the toxic levels defined by the Center of Disease Control (CDC US), thallium is below the toxic thresholds and cadmium reaches the toxic limit. Other potentially toxic metals are 2-3 (lead, arsenic) to 10 (manganese) or even 100 times (vanadium) above toxic levels. Our measurements of titanium and uranium are within the range of published data, with no apparent excess. Only Ti and Tl concentrations in the blood appear to be significantly correlated with IQ measurements (Tl-QI associations: -119.7,95% CI and Ti-IQ: 1.14;95% CI). Pupils' Ti-IQ was also negatively associated with the use of mains water (-3.9; 95% CI ) and age (-1.4; 95% CI ). The associations between independent variables were (Pb; Cu; BMIz), (Sr; gender), (V; Mn; use of mains water) (Cu; Cd; age). This study provides the first indicators of high levels of metal contamination in the blood of a cohort of children attending school in Afghanistan, with associations that need to be confirmed by further studies, and the sources clearly identified. This data is a unique and essential tool for public health players in Afghanistan, enabling them to characterise the extent of intoxication in children and its origins, which will need to be monitored as closely as possible to their living environment.
*The thesis jury will be composed of Dumat Camille (University of Toulouse), Oulhote Youssef (Icahn school of Medicine, US), Flament Pascal (Université du Littoral Côté d'Opale), Glorennec Philippe (Ecole des hautes études en sante publique), Auffan Mélanie (CEREGE), Alain Véron Thesis Director (T&P, CEREGE), Laporte Rémi (AP-Hôpitaux de Marseille).