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PK Verkasalo 1 , E Kokki 1 , E Pukkala 2 , T Vartiainen 1 , J Pekkanen 1

High Levels of Dioxins in River Sediments and Cancer Risk in Nearby Farmers: A Case Study using a GIS application. PK Verkasalo 1 , E Kokki 1 , E Pukkala 2 , T Vartiainen 1 , J Pekkanen 1 1 National Public Health Institute 2 Finnish Cancer Registry. Background.

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PK Verkasalo 1 , E Kokki 1 , E Pukkala 2 , T Vartiainen 1 , J Pekkanen 1

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  1. High Levels of Dioxins in River Sediments and Cancer Risk in Nearby Farmers: A Case Study using a GIS application PK Verkasalo1, E Kokki1, E Pukkala2, T Vartiainen1, J Pekkanen1 1National Public Health Institute 2Finnish Cancer Registry

  2. Background • The River Kymijoki is one of the largest rivers in southern Finland with close to 190,000 people living within 20 km from its shoreline • The sediment levels of dioxins in the river are between 0.5 and 350 ng g-1 (I-TEQ) and thus among the highest in the world • The dioxins originate from the production of a chlorophenol product where they occurred as an impurity • 2-3-7-8-TCDD is classified as a human carcinogen by IARC

  3. Hypothesis • We hypothesize that dioxins are mobilized from the river sediments and accumulate in the nearby residents via the food chain • Therefore the people and especially the farmers living closest to the river are suspected to be at the highest risk • We also explore the cancer patterns in people living near the river and the additional effect of living close to the Baltic Sea

  4. Methods • Small area statistics on health (SMASH) -system • whole of Finland divided into squares of 0.5 km * 0.5 km • for each square data on cancers and population counts by background variables (sex, age and social class) • Study design • exposure was defined as distance of residence to the river shoreline in 1980 (<1 km, 1-4 km, 5-19 km) • follow-up for cancer from 1981 to 2000 • Relative risks • from Poisson models with observed and expected cancers adjusting for sex, age, calendar period, and distance to sea

  5. Risk of total cancer in all residents River Kymijoki 1981-2000; N=187,800

  6. Risk of total cancer in farmers River Kymijoki 1981-2000; N=10,800

  7. Sex Men: 1.17 (0.87-1.56) Women: 1.27 (0.90-1.79) Age in 1980 0-44 years: 1.81 (1.16-2.84) 45-59 years: 1.09 (0.78-1.34) 60 years: 1.04 (0.69-1.57) Calendar period 1981-1990: 1.40 (1.00-1.97) 1990-2000: 1.09 (0.81-1.46) Distance to sea 40-59 km: 0.94 (0.46-1.95) 20-39 km: 1.46 (1.03-2.07) <20 km: 1.14 (0.83-1.57) Risk of total cancer in farmers* <1 km to the River Kymijoki 1981-2000; N=1500 *RRs and 95% CIs from Poisson models in comparison to the reference zone and adjusting for all other variables

  8. testis 4.0 sarcoma 2.9 brain 2.6 skin, non-melanoma 2.4 Hodgkin's disease 1.8 breast 1.8 pancreas 1.7 bladder 1.6 liver 1.5 ovary 1.5 thyroid 1.4 prostate 1.3 rectum 1.3 leukaemia 1.3 oesophagus 1.2 non-Hodgkin lymphoma 1.1 lung 0.93 corpus uteri 0.83 kidney 0.74 colon 0.70 stomach 0.61 skin, melanoma 0.40 Cancer pattern in farmers <1 km to the River Kymijoki 1981-97; N=1500

  9. Discussion about the method • Exposure assessment is based on the location of residence at one point in time • Rapid analyses can only provide first approximations of risks • In case of negative results, you need to be cautious not to exclude a real effect • In case of positive results, the method provides only limited evidence on causality

  10. Discussion about the results • The results are compatible with a dioxin effect or an effect in reproductive cancers • Some of the risk increases could be explained by alcohol, chemicals or mutagenic drinking water • The results are unlikely to be explained by smoking, dietary habits or solar exposure

  11. Thank you!

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