Exposure to thallium contamination in drinking water: first results of human biomonitoring in Pietrasanta (Lucca, Italy).

Nuvolone D 1, Aprea C 2, Sciarra G2, Petri D1, Pieroni S3, Bertelloni S4, Cipriani F1, Aragona I 3.

1. Unit of Epidemiology, Regional Health Agency of Tuscany, Firenze 2. Public Health Unit, South-East Tuscany, Siena 3. Department of Prevention, Versilia Area, North-West Tuscany, Pietrasanta 4. Unit of Pediatrics, University Hospital of Pisa, Pisa

Since the end of 2014 in Pietrasanta (Lucca, Italy) Thallium exposure several bans on the use of drinking water have Valdicastello Pietrasanta-centre been established by the municipality because of Pollino high thallium levels (above EPA guidelines of 2 Pietrasanta µg/l) detected in some areas of the drinking water system. Due to its rare presence at high concentrations thallium is not included in the list of drinking water parameters, according to European and national legislation. The source of contamination has been identified in the thallium-bearing pyrite ores occurring in the abandoned mining sites of the area. Thallium exposure areas Residents Population exposure stopped when pollution Valdicastello sources were excluded, and some pipes tracts 1,500 were replaced or cleared. Pietrasanta centre 3,500 The main objective of this study was to assess the Pollino degree of thallium exposure in a population living 1,700 in areas of Pietrasanta involved in contamination of Pietrasanta 25,000 drinking water.

86% of participants provided both samples. Urine thallium levels were compared with SAMPLING A reference values provided by the Italian Society for Reference Values (SIVR) and USA The first set of samples was reference populations (Centers for Disease Control and Prevention– CDC Atlanta) collected within 30 days from water usage ban (samples A). 0.6 BIOMONITORING 0.5 Various human bio-monitoring 0.4 campaigns have been carried- SAMPLING B 0.3 out, by detecting urinary thallium The second set was 0.2 levels collected after 2 months 0.1 (samples B). Some samples 0 USA (CDC) USA (CDC) USA (CDC) USA (CDC) USA (CDC) SIVR 2011 not participating to the first age >20 y age >20 y age >20 y age 6-11 y age 12-19 y survey were collected too. 95th percentile 0.5 0.41 geometric mean 0.1 0.142 0.152 0.137 0.161 0.15

RESULTS BY AREA OF RESIDENCE RESULTS – ALL SAMPLES 637 samples A and

10 700 samples B were VALDICASTELLO SAMPLES analysed, accounting 10 8 for 20% of total 9 8 6 population living in 7 6 4 the contaminated 5 areas. 4 2 Geometric mean (GM) 3 2 0 geometric mean min max of samples A was 0.42 1 0 Sample A (N=637) 0.424 0.005 8.96 µg/l (min-max: 0.005- SAMPLE A - GM SAMPLE A - MAX SAMPLE B - GM SAMPLE B - MAX Adults (N=399/437) 0.469 3.24 0.321 5.44 Sample B (N=700) 0.286 0.005 5.44 8.96 µg/l). Children (N=67/77) 0.541 8.96 0.244 1.82 Adolescents (N=29/31) 0.641 3.11 0.31 0.92 Women (N=276/304) 0.453 8.96 0.296 5.09 At cessation of exposure, samples B showed a significant decrease of thallium levels Men (N=219/237) 0.534 3.11 0.325 5.44 Valdicastello higher area (N=183/184) 0.777 8.96 0.352 5.44 (GM: 0.29 µg/l; min-max: 0.005-5.44 µg/l). Valdicastello medium area (N=234/264) 0.404 5.14 0.316 5.09 42.5% of samples A and 20.9% of samples B showed thallium levels above 0.5 µg/l, Valdicastello lower area (N=78/81) 0.287 2.6 0.227 1.25 which is 95° percentile of SIVR reference population Samples collected in Valdicastello showed a significative geo-graphical trend: samples from the higher area of Valdicastello (nearer to thallium contamination source) have the highest thallium urinary levels. No significant association by age and sex was . RESULTS – PAIRED SAMPLES PIETRASANTA SAMPLES 2 0.9 Subjects participating in 1.8 Samples collected in the 0.8 1.6 historical centre of both surveys (samples 1.4 0.7 A and B) show a 1.2 Pietrasanta have lower 0.6 1 thallium urinary levels 0.5 significant decrease of 0.8 0.6 0.4 than those collected in thallium urinary 0.4 0.3 concentrations. This 0.2 Valdicastello. 0.2 0 reduction is more SAMPLE A - GM SAMPLE A - MAX SAMPLE B - GM SAMPLE B - MAX No statistical significant 0.1 Adults (N=77/83) 0.305 1.87 0.236 1.1 association by age and 0 pronounced in those Children (N=58/64) 0.195 0.687 0.192 1.18 SAMPLE A - GM SAMPLE B - GM areas nearer to the Adolescents (N=8/9) 0.444 0.837 0.277 0.581 sex was found. Valdicastello higher area (N=178) 0.763 0.36 Women (N=76/82) 0.238 0.998 0.203 1.1 0.403 0.322 pollution sources, i.e. Valdicastello medium area (N=233) Men (N=67/64) 0.286 1.87 0.237 1.18 Valdicastello lower area (N=76) 0.277 0.244 the higher area of Pietrasanta centre (N=133) 0.268 0.218 Valdicastello CONCLUSIONS Among those who have PAIRED SAMPLES Population living in Pietrasanta areas interested by drinking water contamination showed SAMPLES B >0.5 µg/l still shown thallium levels average urinary thallium levels higher than reference values. 30 subjects have sample B > sample A above 0.5 µg/l (95° adjusted for measurement uncertainty percentile of SIVR WHO, Thallium. International Programme on chemical safety. Environmental reference popultaion) in Health Criteria 182 (1996) SAMPLE A the second survey “The Task group considered that exposure causing urinary thallium SAMPLE B (sample B, after concentrations below 5 µµµg/L are unlikely to cause adverse health effects. In cessation of exposure), the range of 5-500 µg/L the magnitude of risk and severity of adverse effects 30 subject still have are uncertain, while exposure giving values over 500 µg/L have been sample B > sample A, associated with clinical poisoning” taking into account Even though Pietrasanta samples showed mean urinary levels far below this WHO value, samples diluition and poor epidemiological evidence on chronic exposure to thallium imposes strong caution on measurement uncertainty evaluation of health effects.

28 ° Annual Conference International Society for Environmental Epidemiology , 1 -4 September , Rome