Identification of volatile organic compounds emitted in the field by oilseed rape (Brassica napus ssp. oleifera) over the growing season.

BACKGROUND: Oilseed rape has been associated by rural dwellers with seasonal symptoms, such as sneezing, coughing, headache and eye irritation, during its flowering season, for a number of years. This study was performed to identify the volatile chemicals emitted from oilseed rape in the field. OBJECTIVE: The objective of this study was to establish which volatile chemicals may be causative factors of oilseed rape allergy/toxicity. METHODS: The volatile organic compounds were sampled over the flowering period using a modified entrainment technique for headspace analysis under field conditions. These volatiles were then identified using thermal desorption-gas chromatography-mass spectrometry. RESULTS: The major constituents identified were the monoterpenes limonene, sabinene, beta-myrcene, and cis-3-hexen-l-ol acetate, a 'green leaf' volatile. The minor constituents included monoterpenes, sesquiterpenes, short chain aldehydes and ketones, other 'green leaf' volatiles and organic sulphides including the respiratory irritant, dimethyl disulphide. CONCLUSIONS: This report highlights the diversity of volatile chemicals emitted by oilseed rape and confirms field emissions to be broadly similar to those found previously in laboratory studies. A review is carried out on the scientific literature already published on oilseed rape flower headspace analysis.

Evidence that oilseed rape (Brassica napus ssp. oleifera) causes respiratory illness in rural dwellers.

A study of 25 residents in a small Scottish village over a two-year period investigated respiratory symptom reporting in the presence or absence of oilseed rape. Symptom reporting in the year when oilseed rape virtually surrounded the village, varied during the growing season of the crop and was at its highest coincident with peak flowering. At the same period of the following year when the crop was absent, symptom reporting was significantly lower. The symptoms which correlated most strongly with peak oilseed rape flowering were sneezing, cough, headache, eye irritation and the total of these and other symptoms. Increased symptoms were reported by 12 of the participants though only seven of these were judged to be atopic. The symptoms did not correlate with levels of oilseed rape pollen but there is no clear evidence as to which of the other factors associated with the crop might be the cause.