Document LkLM7dEB5BGb39VJ4kn09XDb

(foprmttd from Sanere, Vol. ill, No. 5046, pp. 259-261, 7u!y 16, 1966) ORGANOCHLORINE PESTICIDES IN THE ATMOSPHERE By Dr. D. C. ABBOTT, R. B. HARRISON, J. O'G. TATTQN . and Dr. 1. THOMSON Ltboritory of the Government Chemist, Cornwall House, Stamford Street, London. S.E.I The probloms introduced by tho pollution of our atmoiphorio onvironmont liavo boost concornod largely with those pollutants tlso offocts aisd prosenco' of tvliioh aro readily demonstrated, for oxamplo, Bmog, sulphur dioxide, sooty rantorials and dusts. More recontly, attontion has boon diroctod to the polynucloar hydrocarbons1-*, al though thoir presonco in nir is by no moans sololy of modem origin. Itooont publications have given ovidonoe for tho prosenco of eomo organochlorino pusticidoB in rainwater**. It lias boon suggested4 that tho minuto traoos found aroso from tho 'scrubbing' action of tiio falling rnin on tho air through which it passed, in a manner analogous to the collection of the inorganic constituents of rainwater'. Tile present work doacriliCK the experiments whicli liavo been carried out to nscurLim tho extent to which tliuso organochlorino compounds are present in tho atmosphere. PoBticidnl compounds may outer tlio atmospheric onvironmont in sovornl ways and in various physical states. Direct drift from spraying operations will con tribute parUculnte or globular matter at concentrations which are likely to vary inversely ns the distance from the site of application, such effects being mainly local but possibly appreciable in extent. It has boon shown'-* that several organochlorino insocticidos volatilize from treated soils, thus adding a slow, long-tonn contribution. Effluents and vapours from industrial prooosses, such as poBlicide manufacture or moth-proofing of garments, may also contribute, whilo further quantities may neerno from tho uso of domestic aerosol insecticides and thermal vaporizere, and tho dust from treotod clothing and carpets. Wheatley and Hardman* oxamined rainwater for tracos of pesticides in order to try to account for residues found in soil from untreated plots of land. Tho amounts which they found wore insufficient to account for more than a very small proportion of the postioidos present in such soil. Although the concentration of these compounds in nir is lower by a factor in tlio rnngo of 10-100 than that, in rainwater, the vastly grantor volumes of nir may rondor this contribution of greater significance. As woll ns tho normal, constantly chnnging contact betwcon air and soil, tho mass of air. in surfneo soil may nltor by up to 0 per cent owing to diurnal variations in temperature- Pesti cides may thus, bo absorbed by tho soil noting as a gassolid chromatographic 'column' ns well ns by direct surface adsorption mechanisms. Assuming a tendency to equili brium, treated soils will lose pesticides while untreated plots will gain them. Preliminary experiments to illustrate the presence of pesticides in nir wore carried out by using a smnl) portnblo confttniit-rnto nir-snmpler which was used to suck nir through a hexane trap. Although this method gave a total sample of only about 180 1. of nir ]>er powor-onnistcr. gas-liquid chromntography showed the prosenco of traces ofBHC. DDT, DDE, TDK and dioldrin in samples taken in central London and its suburbs. Dioldrin alone was observed in n Bmnplc token in Xorfolk, while Aberystwyth nir gavo no detectable amounts of pesticide at this sample size. It. was clenr from these preliminary observations that an analytical problem oxisted and (hot larger samples would be requirad before reliable data could be obtained. Accordingly, an electrically operated vacuum pump oapablo of drawing 15 1. of nir per min for long periods of timo was brought into uso. At this rnto of flow hexane was too volatilo, but dimethylformamido proved to bo a suitablo, non-volatile extractant. Examination of tho soparato contents of a sequential train of four solvent traps showed that noarly all the poBtieido contont was rotained in tlio first vossol. Attempts hnvo also been rnndo to ascertain whether tho pesticides prosont wore in tho vapour Btate or in association with tho particulato matter of tho air. Interposing bacteriological membrane filters (poro size 0-22 p) botwoon tho air inlot and tho solvent trap showed that variable proportions of tho pesticides woro retained on the filter. Tho amount retained, however, tondod to roach an equilibrium value, indicating that the compounds woro volntilizing again from the filter into the air atronm. iSimilar offeets have been observed with some polynucloar hydrocarbons'. Thus, ulthough the use of mombrono filters offers a simplo qualitative test for pcsticidos in air, quantitative results can only be obtained by solvont scrubbing procedures. SOLVENT " FRONT' # DDE O-BHC HEEPPTOAXCtDHELOR y&HC Si I ct ft S' CICtOSIN r-BHc riB.l. TMn-ln[crel>romfltoi>liile Metropolitan air was sampled by suction at about. 15 l./min through 100 ml. of dimothylformomide con tained in a Drochscl bottlo fitted with a coarse sinter at the inlet to tho solvent to ensure adequate diffusion. Dispersion of tho solvent in 500 ml. of 5 por cont sodium sulphate solution followed by hexane extraction yielded a clean solution which, after evaporation to smnl) bulk, was applied to a 250 p silica-gel chromatoplato. This was developed with hcxnno .-aeotono, 09 + 1, for 35 min and appropriate fractions olutod with hoxanc10 for exami nation by gas-liquid ohromatograpliy on both silicone and `Apiczon' columns with oleetron-capturo detection11. Fig. I shows tho positions on tho thin-layer pint or tho more important organochlorino pcsticidos and indi cate? tho areas containing tho residues which woro re- i > ! DSW 162214 STLCOPCB4040831 moved for examination. Figt. 2-4 Illustrate goa-ohromato- grapb traces obtained from some of these areas; poak* corresponding to known posticidal materials aro morkod-- tho Other peaks have not boon positively idontiflod os yet. The appoaranoo of u ponk at tho appropriate retention time on two ohromatographio columns of differing polarity on injooting the oluate from tho chromatoplato area of oorreot Rr value for tho compound concerned has boon takon os ovjdonoo of tho idontity of tho compounds. Tablo ! lists tho quantities of poBtioidos found on exami nation of 8,000 1. of olr taken on tho roof of Cornwall House in August, 1900. Tho prosence of alpha-BHC, gumma-BHC, dieldrin (HEOD), pp'-DDE, pp'-TDE and pp'-DDT was confirmed as already described; substantial agreement between quantitative results on both columns oonfirmed the absenoe of any appreciable amount of interfering non-pestioidal material of similar retention time. - hydrocarbons aoonaphthyleno (Rr 0-67), anthracene (0-67), fluoranthene (0-57) and (luorono (0-70). Kotcntion timos on both oolumns confirmed those identities; those substances arc known to bo among tlm polyiiucl'inr liydrocarbon ingredients of atmospheric dusts1-11. Tho throo poakB of longest retention timos obtained from section 1 of tho chromatoplato (Fig. 2) would seem to result from compounds tho behaviour of which on the plato and on each column ib identical with that shown by tho compounds giving tho first threo of a scries of unidenti fied peaks often found in chromatograms of oxtracts from Tab. 1. OKaAifooBiaBDfB Festiob-es fochd nr Loxdox Air Compound Alpha-BHC Oamtta-BHC Dleldrln (HBOD) pp'-DDB PP'-IIDT pp'-TJ>E Hr range of Concentration found (jwitapcr chromatoplato area 10" w/rr) by gae-llquld chromato* Krnphy on (ft) silicone .901' (b) 'Aplezon V 0-S7-0-48 1 1 0-87-0-30 6 11 017-0-86 18 21 0-76-0-84 O-ti-QW 0-S7-0-48 4 3 3 7 3 8 Bllloa-gl ehromatoplate developed with hexane; eoetone, M +1. Silicone oolumn: 1-2 per oent illloone .801 Plue 0-12 per oenl 'Eplkote 1001' on 'Sllanlted Chrcmotorb O' (70-90 meihfat 188* C; nitrogen carrier CM. 100 ml./mln. 'Apteeon' oolumn; 8 per oent 'Aploron V plue 0-1 per oenl `Eplkote 1001' on `Cellte 8(5' (100-120 meet) at 180* C; nitrogen carrier gee, 100 ml./mln Great oare must be taken in the interpretation of the gas-liquid ohromatograms obtained from air samples. Even oftor the thin-layer separation process used, each fraction from the plate contained several peaks of unidontifiod materials showing electron-capturing properties. Some of the short-retention time peaks (Fig. 3) corre sponding to section 2 of tho ohromatoplate {Rp 0-58-0-66) have boon tentatively identified as the polynuclear Fig. 8. Ofts-llquld ohromatogrsm from ftcctlim 2 of tiro Iblr.-lr.y-.: ehromatoplate Fig 2, Ou-llquld chromatogram from Mellon i of the thin-layer ohroraetoplnic Fig. 4, Ont-llquld chromatogram from Motion 8 of the thin-layer dhronifttoplftte r .. 1 DSW 162215 STLCOPCB4040832 the tissue and eggi of tome predatory birds. Their con Confirmation of tho identity of these residues by other centrations relative to eaoh other in these two samplo methods such as infra-red spectroscopy or mass Bpoctro- aourcee are also closely similar. Total ohlorine determina metry would also be desirable, although far larger samples tions on avian tissue samples have indioatod that these would be required in order to obtain sufficient material compounds contain chlorine, and beoauso they are only in a suitably pure state. It would aleo bo of interest to found In samples containing appreciable residues they are compare tho levels found in London with thoso found in probably breakdown products of organochlorine pesti other parts of the country; soasonal variation and cor cide*. relation with other indices of atmosphorio pollution The evidence presented here and from rainwater would also be worth investigation. In these ways it may examination*'* indicates the general occurrence in the be possible to obtain some indication as to whether tho atmosphere of minute traces of some of tho persistent posticides derive from within the shores of the British orgonoohlorino postioidoa. Such compounds have also Isles or from further afiold. boon found in samplos of air taken during tho spraying season in Amorioan pooch-orchard districts1'. Tho concentrations of those residues arc so low that it is 1 ftawlckl, E,, Stanley, T, W,, Blbcrt. W. C., and PfalT, J. !>., 49? (1904). Chem., I Ltbcrtl. A- Cartonl, P,, and Cumuli, V., J. Cftromalofl., U, 141 (1M4). necessary to work almost at the limit of sensitivity of tho ' Swickl, E., Hooker, J. E., and. Morgan, M. J., Intern, J. Air Water 1`oM,, detection systems at presont in ubs. For this reason, scrupulous care is necessary in order to avoid contamina 9. 291 (1905). * Wheatley. 0. A.. and Hardman, J. A., yatwe,Z07, 480 <19G5). * Abbott, D. C.. Harrison, P. B., Tntfon, J. O'O,, nd Thomson, J., yature, tion at eaoh manipulative stage, from tho initial apparatus 808. 1817 (1005). preparation to tho final injection on to the gas chromato * Bgnor, H., Broilln, 0., and Johansson, O., Annul. Agrie. Coll. Svtden, 82, 300 (1055). graph. Blank experiments muBt bo performed at each * Decker, O. C., Wclpmnnn, C. J., end Bsnn. J. M., J. Eem. Bnlomot., 48. stage and on all materials used. Particular care is required ' 019 (1950). to oxolude laboratory dust, for it !b found that it is frequently a carrier of interfering eloctron-capturing * Harris. C. K-. and Lichtenstein, E. P., /. Econ. Entomol, M, loss (190)). * Rondla, D., Jntfrn. J.Air Water Poll,, 0,113 (1905). ** Harrison, K, B.. J. Sci. Food Aerie., 17,10 (I960). materials. II de Fauberl Maunder, M. J., Egan. IT., and Boburn, J.. Anohut, BO. JO? Although the levels concerned are extremely low, these (1004). indications of tho presence in air of organochlorine postioides call for further and more detailed investigation. H Canluti, V., Carton), O. P., Llbcrtl, A., and Torrl, A. G.. J. Chromal/#., 17. OO (1905). , " Breldenbach. A. IV.. Ardi, Emir. Health, 10.827 (1M5). Printed In Gtcat Britain by Fisher. Knixht & Co., Ltd., St, Albans. DSW 162216 STLCOPCB4040833