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 lThe River Kymijoki is one of the largest rivers in southern Finland with close to 190,000 people living within 20 km from its shoreline lThe 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 lThe dioxins originate from the production of a chlorophenol product where they occurred as an impurity l TCDD is classified as a human carcinogen by IARC

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

lSmall 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) lStudy 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 lRelative risks –from Poisson models with observed and expected cancers adjusting for sex, age, calendar period, and distance to sea Methods

Risk of total cancer in all residents River Kymijoki ; N=187,800

Risk of total cancer in farmers River Kymijoki ; N=10,800

Risk of total cancer in farmers* <1 km to the River Kymijoki ; N=1500 Sex Men: 1.17 ( ) Women: 1.27 ( ) Age in years: 1.81 ( ) years: 1.09 ( ) 60 years: 1.04 ( ) Calendar period :1.40 ( ) : 1.09 ( ) Distance to sea km: 0.94 ( ) km: 1.46 ( ) <20 km: 1.14 ( ) *RRs and 95% CIs from Poisson models in comparison to the reference zone and adjusting for all other variables

Cancer pattern in farmers <1 km to the River Kymijoki ; N=1500 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

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

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

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