Arsenic is a naturally occurring substance in soil and groundwater, but it can also be present in soil and groundwater through past human activities. When people grow their own vegetables on plots contaminated with arsenic, they may unintentionally ingest soil particles whilst tending their crops and in doing so, they may ingest arsenic. This is also possible when eating vegetables that have been grown on soil contaminated with arsenic.
RIVM was requested by the municipal health services (GGDs) to advise on the assessment of the human health risks of growing vegetables in soil contaminated with arsenic. This assessment is difficult because it is uncertain how much of the arsenic in the soil accumulates in vegetables. In addition, a current guideline value for 'tolerable exposure' to arsenic is lacking.
This guidance provides an indication of a state-of-art guideline value for 'tolerable exposure' to arsenic. A conservative estimate (based on high exposure) of exposure to arsenic through vegetable consumption was made, because the assessment of the accumulation of arsenic in vegetables is unpredictable cumbersome. Subsequently, the exposure to arsenic through growing vegetables was compared to the so-called background exposure. This is the intake of arsenic by the general public through purchased foods such as rice, cereals and milk, drinking water and possibly other exposure routes, independent of local soil contamination. It was calculated that exposure through the vegetables which people are more likely to grow themselves contributes about 10% to background exposure; the remaining background exposure is predominantly from other food products.
Finally, this report offers advice on how to reduce exposure to arsenic for people who grow their own vegetables. This can be done, for example, through information on how to reduce the amount of ingested soil.