No abstract

A direct, fast and sensitive LC-MS/MS method was developed to measure biomarkers for mycotoxin exposure in human urine. In total, 32 biomarkers were quantitatively or semi-quantitatively measured in 32 urine samples of Belgian volunteers using two injections. All urine samples contained deoxynivalenol-15-glucuronide, the major detoxification metabolite of deoxynivalenol, in the ng/mL range. Also deoxynivalenol-3-glucuronide and de-epoxy-deoxynivalenol-glucuronide were present in, respectively, 90 and 25% of the samples, while deoxynivalenol was detected in 60% of the samples, in lower concentrations. Deoxynivalenol glucuronides were the major biomarkers for deoxynivalenol exposure. Ochratoxin A was detected in 70% of the samples in pg/mL. Citrinin and/or dihydrocitrinone were detected in 90% of the samples, also in concentrations of pg/mL. The presence of ochratoxin A and citrinin was confirmed by a second method using sample cleanup by immunoaffinity columns, followed by LC-MS/MS. Our data show that humans are much more exposed to citrinin than realized before and suggest further work on citrinin exposure in relation with ochratoxin A exposure, as both mycotoxins are nephrotoxic.

Summary A laboratory study was carried out in order to measure the degradation rate of atrazine in 36 different soils taken from maize (Zea mays L.) fields in Belgium. These soils differed in their alrazme treatment histories. pH. organic matter content and type of organic and mineral fertili‐zation, Half‐lives of less than 10 days were found in more than 60% of the soils sampled. This rapid dissipation could be linked in a significant way to repeated pretreaiments with atrazine (intensive maize cropping) as well as to higher pH values (from neutral to alkaline), A low organic matter content might also be a factor explaining the rapid degradation of atrazine. but to a lesser extent than the first two factors. On the other hand mineral fertilization was shown to slow down atrazine dissipation. It is hypothesized that repeated treatments of atrazine cause a mi‐crobial adaptation to atrazine degradation and that acidic soil conditions impede this adaptation. To date, this is the first time that evidence for widespread accelerated degradation of atrazine has been reported.

:In surface soils, atrazine is considered to be a moderately persistent herbicide, with half-lives ranging generally from one to two months. In subsoils, however, its degradation is generally slower. This paper reports the degradation of atrazine in soil and subsoil samples taken from six Belgian maize üelds. Rapid degradation can take place in some samples taken from surface and in some from subsurface soils. Subsoil samples were found to degrade atrazine either very strongly or not at all. Experiments with [ring-U-14C] atrazine showed that the micro-organisms responsible for the rapid degradation cleave the triazine ring and extensively mineralize the molecule.

No abstract