TRIAZINE HERBICIDES and THEIR METABOLITES: METHOD 8315, Issue 1, dated 15 March 2003 - page 5 of 6 GUIDES TO INTERPRETATION: One of the limitations of this method is that different parent triazines are metabolized to the same com pound. Fo r exam ple, de-alkylation of the isopropyl group on a trazine and c yanazine both give des isopropylatra zine, wh ich can a lso be form ed b y the de -alkylation of o ne o f the ethyl groups o f sim azine. Unless exposure is very high the parent compounds are not found in the urine, leaving the analyst with no way of know ing which parent the m etabolite came from in the case of a m ixed expos ure which is very comm on in herbicide applicators. The metabolites and any parent compounds found can be summ ed and reported as total triazine level if desired. There are very few biological monitoring studies of triazines and their metabolites found in the literature on which to develop a good reference range. And to our knowledge there have been no studies or reports on levels of these analytes in the general population. 1. Catenacci (1990) looking at parent atrazine in the urine found maximum excretion rates of 0.14 - 0.42 nmol/hr in workers at an atrazine manufacturing plant and very poor correlation between the concentration in the urine and the concentration in the air. These excretion rates dropped by an order of magnitude or more within twelve hours of the exposure. 2. Ikonen summ ed two metabolites (the desisopropyl atrazine and the bi-dealkylated atrazine, the latter of which was not investigated in this study) and found concentrations of 30-110 :mol/L in railway sprayers. 3. Cate nacc i (19 93) returned to the atrazin e m anufacturing plant w ith an im proved m eth od that co uld measure all three of the de-alkylated metabolites of atrazine and found ranges of 1.1-1.6 :mol/24 hr for the bi-dealkylated metabolite, 0.13-0.21 for desisopropyl atrazine, 0.11-0.20 for desethyl atrazine, and 0.017-0.021 for parent atrazine. To convert to concentration it is possible to assume an average urinary output of 1.1 L/24 hr (Reference 4). Using that assumption and combining the metabolites gives average concentrations ranging from 1.2 - 1.8 :m ol/L. 4. Hines (Reference 5) provides an overview of more recent metabolism studies and results for biomonitoring of the triazines as well as showing the utility of this method (and others) in a study of herbicide applicators. 5. There have been no human studies looking at cyanazine in which to obtain reference ranges of any kind.
EVALUATION OF METHOD: The m ethod was evaluated using 15 spiked urine samples ranging from 5.8 nmol/L - 1878 nmol/L and analyzing these samples on three different days. The recoveries for s-Triazines for compounds (1-5) ranged from 84-88% and fo r com pound (6 ) it was 67%. Precisions and LOD were determ ined from this experiment and are listed on the first page of this method. Sam ple stability was not exhaustively examined. There were, however, samples run after several months that had been stored at -20°C compared to splits of those samples stored at -80°C and no bias was found due to the different storage tem peratures. This wo uld lead one to believe that the samp les would be very sta ble sto red at -80°C for exten ded periods of tim e. T he QC sam ples also tell som eth ing about sa m ple sta bility. T he first batch of these sam ples was stored at -20°C and the control chart sh ow s no trend in these samples even when run over 18 months. There may be some loss of signal on samples that go through multiple freeze/thaw cycles, but conclusive experiments were not done and this may be a function of the am ount of solids that form in the urine during this process an d not becau se the analytes are breakin g dow n. B ecause of this, it is a good idea to aliquot the QC sam ples out into c ontain ers th at w ill only be thawed once or twice and then discarded.
REFERENCES: [1] Catenacci G, Maroni M, Cottica D, Pozzoli L [1990]. Assessment of human exposure to atrazine throu gh the de term ination of free atra zine in urine. Bull. Enviro n. Conta m . Toxicol. 44: 1-7. [2] Catenacci G, Barbieri F, Bersani M, Ferioli A, Cottica D,Maroni M [1993]. Biological monitoring of human exposure to atrazine. Toxicology Letters 69: 217-222.
NIOSH Manual of Analytical Methods (NMAM), Fourth Edition
