Report from the Sub-comittee on the environment and health

Pesticides and degradation products in rainwater samples <strong>from</strong> Zealand. The table shows <strong>the</strong> figures
<strong>from</strong> table 4.15 for <strong>the</strong> deposition of pesticides, calculated as g per hectare (Felding 1998a). The
analysis covers 36 active ingredients and 8 metabolites.
Extracted Isoproturon a Metamitron DNOC b Mechlorprop c Methabenzth
iazuron
2hydroxyterbut
hylazine M
Terbuthyl
azine M
2,4-D c
Sept. 96 0.007 n.d. 0.63 0.005 n.d. n.d. n.d. n.d.
Oct. 96 0.050 0.005 1.13 0.058 n.d. n.d. n.d. n.d.
Oct. 96 0.053 0.038 0.68 0.069 n.d. n.d. n.d. n.d.
Nov. 96 0.018 0.040 0.94 0.074 n.d. n.d. n.d. n.d.
Nov. 96 n.d. n.d. 0.66 0.026 0.011 n.d. n.d. n.d.
April 97 n.d. n.d. 0.64 0.012 0.006 0.075 n.d. n.d.
May 97 n.d. n.d. 0.27 0.013 n.d. 0.086 0.007 n.d.
June 97 n.d. n.d. 0.36 0.007 n.d. n.d. 0.006 n.d.
Aug. 97 n.d. 0.014 0.92 n.d. n.d. n.d. n.d.
Sept. 97 n.d. n.d. 0.08 0.001 n.d. n.d. n.d. 0.009
Sept. 97 0.072 0.037 0.55 0.029 n.d. 0.006 0.003 0.025
Oct. 97 n.d. n.d. 0.45 0.017 n.d. n.d. n.d. 0.013
Oct. 97 0.116 n.d. 0.19 0.030 n.d. n.d. n.d. n.d.
Total 0.32 0.13 7,5 0.34 0.017 0.17 0.016 0.048
Sum of <strong>the</strong> detections of 8.5 g/ha
<strong>the</strong> pesticide chemicals
analysed for
n.d. = not detected; a = ban recommended in 1998
b c
= banned; = banned with dispensation in 1997
M
= metabolite (of atrazine).
In table 4.16, <strong>the</strong> measured concentration of pesticide chemicals <strong>from</strong>
table 4.15 is converted <strong>from</strong> microgramme per litre to gramme per ha. In
this analysis, which does not cover all volatile pesticides, DNOC (4,6dinitro-2-methylphenol)
constitutes just under 90% of <strong>the</strong> total quantity
of pesticide chemicals in <strong>the</strong> atmospheric deposition with rainwater. The
distribution of phenols and nitrophenols in clouds and <strong>the</strong> occurrence and
formation of phenols in <strong>the</strong> atmosphere have been described by Lüttke
and Levsen (1997) and Lüttke et al. (1997). It is concluded in <strong>the</strong>se
studies that DNOC occurs mainly in gaseous form ra<strong>the</strong>r than in liquid
form in <strong>the</strong> atmosphere. Dinitrophenols are mainly formed through
reactions in <strong>the</strong> atmosphere, unlike mononitrophenols, which are
primarily formed in connection with exhaust fumes <strong>from</strong> cars.
4.5.1 Conclusions
Pesticide chemicals have been detected in precipitation collected in
Denmark. The study was limited and covered only a few substances and
not those with <strong>the</strong> highest potential for volatilisation. In most cases, <strong>the</strong>re
was a relationship between <strong>the</strong> spraying season and <strong>the</strong> time of detection.
However, pesticides that are no longer used in Denmark were also
detected. These substances were presumably transported here over long
distances or originated <strong>from</strong> o<strong>the</strong>r sources than treatment with pesticides
in agriculture. The prohibited substances found in <strong>the</strong> precipitation
included DNOC, which was found in rainwater throughout <strong>the</strong> year and
in by far <strong>the</strong> highest concentrations among <strong>the</strong> substances analysed for. It
is <strong>the</strong>refore highly likely that its presence is due primarily to <strong>the</strong>
formation of nitrophenols in <strong>the</strong> atmosphere. The international literature
describes <strong>the</strong> formation of nitrophenols in <strong>the</strong> atmosphere as a reaction
between benzene, toluene and NOx. The exhaust fumes <strong>from</strong> cars contain
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