Report from the Sub-comittee on the environment and health

Xenobiotic substances
cereal crops a major source of people’s intake of cadmium. People’s
intake of lead, cadmium and mercury is generally high. Lead is not
absorbed by plants but lands on <strong>the</strong>ir surfaces in <strong>the</strong> form of small
particles <strong>from</strong> <strong>the</strong> atmosphere. However, national and long-range
transboundary air pollution with heavy metals has been considerably
reduced in <strong>the</strong> last 15 years. Better treatment of flue gas and a ban on
lead in petrol have reduced air pollution. Since 1978, <strong>the</strong> deposition of
cadmium has been reduced by 66%, and atmospheric emissions of lead
have fallen by more than 75%. The use of copper and zinc as growth
promoters in pig production means that <strong>the</strong> content of <strong>the</strong>se metals is
rising on soil regularly fertilised with pig manure <strong>from</strong> herds in which
<strong>the</strong>se growth promoters are used. Both metals affect <strong>the</strong> soil’s
microorganisms and, in high concentrations, can inhibit plant growth.
The metals are not a serious problem in cultivated land today. However,
this does not apply to really contaminated land, e.g. former industrial
sites. Even so, taken toge<strong>the</strong>r, <strong>the</strong> different sources can cause an increase
in <strong>the</strong> soil’s content of heavy metals. The environmental authorities are
<strong>the</strong>refore taking targeted action to reduce <strong>the</strong> use of heavy metals –
particularly cadmium, lead and mercury – in society. Seen in proportion
to <strong>the</strong> impact of pesticides, heavy metals are a bigger health problem than
pesticides, but are not a big environmental problem. With <strong>the</strong>
environment policy pursued, <strong>the</strong> problem is being reduced at source, both
nationally and internationally. Owing to <strong>the</strong> continuing although
diminishing supply, <strong>the</strong> load <strong>from</strong> heavy metals must be monitored on a
long-term basis.
A very large number of chemical substances are used in society. Some of
<strong>the</strong>m end up in wastewater sludge and are <strong>the</strong>reby conveyed to land
under cultivation. In 1997, <strong>the</strong> Danish Environmental Protection Agency
introduced limit values for significant and representative, xenobiotic
organic substances in sludge. It took this action to protect <strong>the</strong>
environment and to promote <strong>the</strong> phasing-out of <strong>the</strong>se substances <strong>from</strong>
<strong>the</strong>ir cycles in society. There are now limit values for a number of tar
substances (PAHs), <strong>the</strong> surfactants LAS, nonylphenols and <strong>the</strong> plasticiser
DEHP. At <strong>the</strong> same time, both ecotoxicological and human toxicological
soil quality criteria have been set for a wide range of substances that can
occur as contaminants in soil or waste products. A number of studies are
in progress to determine whe<strong>the</strong>r <strong>the</strong>se protection levels are adequate.
Xenobiotic substances can also be present in low concentrations as
contaminants in animal feed. The substances in question are banned
pesticides, such as DDT and toxaphen, and industrial contaminants, such
as PCB. These substances can be supplied to plants during <strong>the</strong>ir growth
period as atmospheric deposition as a consequence of long-range
transfrontier atmospheric pollution, toge<strong>the</strong>r with combustion products,
such as PAHs and dioxins. The cleaning products used by farmers for
cleaning stables contain LAS and nonylphenol compounds. Small
amounts of plasticisers, e.g. DEHP, are released <strong>from</strong> hoses, tanks, paint
and plastic objects. The total supply means that manure also contains
xenobiotic substances, which reach soil under cultivation by this
pathway. Lastly, <strong>the</strong>re is a direct supply of contaminants <strong>from</strong> <strong>the</strong>
atmosphere to plant surfaces and <strong>the</strong> soil. The contaminants in question
are PAHs, PCB, dioxins, chlorinated phenols and benzenes, toge<strong>the</strong>r with
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