A multi-environmental media approach to explore the association between metal exposure and the ability to identify smells among school-age children residing in Northern Italy

Abstract

BACKGROUND AND AIM Inhalation of airborne particles can lead to olfactory dysfunction. We aimed to test the association between the exposure to a mixture of 12 metals measured in three environmental media and olfactory function among children and adolescents residing at different distances from ferromanganese alloy plants in the province of Brescia, Italy. METHODS We enrolled 130 children between 6 and 13 years old (51.5% females) residing in Valcamonica and Bagnolo Mella, respectively. The Burghart "Sniffin` Sticks” test was used to investigate olfactory performance in identifying smells. Metal concentrations in soil, indoor, and outdoor deposited dust samples from the subjects’ households were analyzed with a portable X-ray fluorescence instrument. A Multi Environmental Media (MEM) Weighted Quantile Sum (WQS) regression for count data was applied to test for the association between the exposure to metals and child olfactory function. All models were adjusted by age, sex, socio-economic status, area of residence, intelligence quotient, BMI and passive smoking. RESULTS The metal mixture was negatively associated with the identification score (=-0.229; 95%CI -0.439, -0.018). Cadmium (17.0%), iron (13.0%), lead (11.5%) and arsenic (8.5%) provided the strongest contribution to the association. Indoor dust resulted as the environmental media with the strongest contribution to the association with olfactory function for most of the elements considered in the mixture. CONCLUSIONS We identified metal concentrations in indoor dust as a risk factor for olfactory dysfunction in children and adolescents residing close to ferroalloy plants. Indoor pollution can be improved through public health interventions; moreover, the identification of the factors that can deteriorate olfactory functions can also prevent neurodegenerative disease. KEYWORDS Environmental exposure; olfactory function; metal exposure; soil; outdoor dust; indoor dust.