OR/18/052 Emerging substances in UK groundwater

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Lapworth, D J, Crane, E J, Stuart, M E, Talbot, J C, Besien, T, and Civil, W. 2018. Micro-organic contaminants in groundwater in England: summary results from the Environment Agency LC-MS and GC-MS screening data. British Geological Survey Internal Report, OR/18/052.

Key substances with high frequency of detection[edit]

Table 4.1 shows the ten most frequently detected substances by the GC-MS method and summary details of their regulation. Six are pesticides, or their TPs, or halogenated solvents and are covered by the Drinking Water Directive (DWD 98/83/EC). Four of these are hazardous or priority hazardous substances under by the Priority Substances Directive (2008/105/EC). Two of these also appear in Annex XIV of the REACH Regulations. None are on the surface water watch list (SWWL), which is linked to the Water Framework Directive (2000/60/EC and later amended by 2008/32/EC).

Table 4.1    Regulation of GC-MS frequently detected substances.
Substance Type Use

Regulationa&b

DWDa Limit (μg/L) Other Status
Atrazine Pesticide Herbicide Y 0.1 (0.5 total) PPPb
PSDa
Withdrawn Hazardous substance
TCE Halogenated solvent Degreaser and feedstock for CFCs Y 10 (PCE+TCE) PSDa
REACH
bAnnex XIV
Equivalent to Priority substance SVHC
BPA Plasticiser Polycarbonates and epoxy coatings N Food contact
REACHb
Food packaging for infants ECHA candidate
Dimethyl succinate PPCL Flavouring fragrance plus industrial N
Desethyl-atrazine Pesticide Herbicide TP Y 0.1 (0.5 total) Parent withdrawn
PCE Halogenated solvent Degreaser, dry cleaning Y 10 (PCE+TCE) PSDa
REACH
bAnnex XIV
Equivalent to Priority substance SVHC
DEET PPCL Insect repellent N Biocide regsb
Cyclo-hexanone Industrial Nylon precursor and many other uses N
Fluoranthene PAH Waste product Y PSDa Priority substance
Pyrene PAH Waste product Y SVHCb

DWD – Drinking Water Directive, PPP – Plant Protection Products regulation, PSD – Priority Substances Directive, SVHC – substance of very high concern (REACH Regulations).
aend-of-pipe regulation and bSource regulation.


Table 4.2 shows the ten most frequently detected substances by the LC-MS method and summary details of their regulation. Six are pesticides, or their TPs, and covered by the Drinking Water Directive; four are common to Table 4.1 Three of these are hazardous or priority hazardous substances under by the Priority Substance Directive. Two are industrial/flame retardants which appear in Annex XVII of the REACH Regulations. One of the pesticides is on the SWWL.

Table 4.2    Regulation of LC-MS frequently detected substances.
Substance Type Use

Regulationa&b

DWDa Limit (μg/L) Other Status
Deisopropyl-atrazine Pesticide Herbicide TP Y 0.1 (0.5 total) Parent withdrawn
Simazine Pesticide Herbicide Y 0.1 (0.5 total) PPPb
PSD
Withdrawn Hazardous substance
Atrazine Pesticide Herbicide Y 0.1 (0.5 total) PPPb
PSDa
Withdrawn Hazardous substance
Diuron Pesticide Herbicide Y 0.1 (0.5 total) PPPb
PSDa
Withdrawn Hazardous substance
Carbamazepine Pharmaceutical Epilepsy/bipolar disorder N
Clopidol Pharmaceutical Veterinary N
PFOA Perfluorinated organic Industrial N REACH
bAnnex XVII
Restricted in consumer products
Clothianidin Pesticide Neonicotinoid Y 0.1 (0.5 total) SWWLa Monitored
PFOS Perfluorinated organic Industrial N PSDa
REACH
bAnnex XVII
Priority substance Restricted

DWD – Drinking Water Directive, PPP – Plant Protection Products regulation, PSD – Priority Substances Directive, SWWL – surface water watch list.
aend-of-pipe regulation and bSource regulation.


In some cases a substance can belong to more than one regulatory regime, these are summarised by key substances types in Table 4.3.

Table 4.3    Current EU chemical substance source regulations.
Chemical Substance Type European Legislative Body (Regulation)
Industrial & consumer chemicals ECHA (No. 1907/2006)
Human pharmaceuticals EMA, EMEA/CHMP/SWP/4447/0
Veterinary medicines EMA
Plant protection products EFSA (EC 1107/2009)
Biocides ECHA (EU 528/2012)

ECHA – European Chemicals Agency, EMA – European Medicines Agency, EFSA – European Food Safety Authority.

Comparison with previous studies[edit]

Most of the GC-MS data is common to this study and previous BGS studies reported in 2012 and 2016 which used Environment Agency monitoring data, but the current study differs in several respects:

  • It contains more recent data up to 2018
  • It has been restricted to GC-MS targeted screening data only, whereas the other studies also included some data provided by other analytical methods, e.g. SVOCs
  • The GC-MS method is continuously updated with new compounds being introduced and identification algorithms being improved to reduce false positives.
Figure 4.1    Top 30 most frequently detected compounds from 2016 assessment.

Figure 4.1 shows frequency data from the 2016 study (Manamsa et al., 2016[1]). There are fewer detections overall in the current study as results from methods other than GC-MS have been excluded. Similar compounds remain prominent in the current study in most frequent positions:

  • The pesticide atrazine remains the most frequently detected compound but its desethyl TP is less prominent in this dataset
  • The halogenated solvents TCE and PCE are found at higher relative frequencies as are the plasticisers BPA and DEET, and the industrial compounds cyclohexanone, dimethyl succinate and dimethyl adipate
  • Caffeine has become less prominent as have some PAHs.

Figure 4.2 shows maximum concentration data from the 2016 study. Compounds in Figure 4.2 do not compare very well with the current study (see Figure 3.3). This reflects the exclusion of data from non-GC-MS screening methods in this review and also that these maximum concentrations may be random outliers and do not reflect typical concentrations.

The halogenated solvents are less prominent in the current study than in Figure 4.2 and particularly reflect the exclusion of solvent data from non-GC-MS methods. Plasticisers remain prominent and BBSA is the most frequently detected compound in the current study. Of the PPCL compounds, dimethyl succinate did not appear in the top 30 in 2016.

Figure 4.2    Top 30 maximum concentrations from 2016 assessment.

Implications for using quantitative analytical suites[edit]

Compounds detected[edit]

Many of the most frequently detected compounds in the GC-MS results would not be detected by the dedicated suites currently used by the Environment Agency. These dedicated suites are shown in Table 4.4.

Table 4.4    Environment Agency quantitative suites.
Suite code Suite name Typical member LOD (μg/L)
GWQM01 ONP pesticides Atrazine & TPs, diazinon 0.001–0.02
GWQM02 ONC pesticides Trichlorobenzene, diclobenil, PCBs, aldrin 0.001–0.02
GWQM03 Acid herbicides Bentazone, clopyralid, mecaprop 0.005–0.04
GWQM04 Urons/urocarbs Azoxystrobin, carbendazim, isoproturon 0.005–0.1
GWQM05 Phenols Chlorophenols 0.002
GWQM06 VOCs Halogenated solvents, BTEX 0.01–0.5
GWQM07 PAH Anthracene, chrysene, fluoranthene 0.01
GWQM08 Pyrethroids Cypermethrin 0.00001–0.0001
GWQM09 Discretionary Chlormequat, fluazaflop-butyl 0.01–0.2
Special-site-by-site Glyphosate, AMPA, metaldehyde 0.01–0.1
PFOS/PFOA 0.005–0.1

Table 4.5 indicates that 60% (30/50) of the top 50 compounds found by the GC-MS method do not appear in the standard suites. These are predominantly industrial, plasticisers and PPCL compounds with a small number of pesticides and pesticide TPs.

Table 4.5    Compounds detected by GC-MS screen not present in standard suites.
Ranking CAS Number Analyte Short name Use code *
G03 80057 Bisphenol A BPA Plast
G04 106650 Butanedioic acid, dimethyl ester Dimethyl succinate PPCL
G07 134623 N,N-Diethyl-m-toluamide DEET PPCL
G08 108941 Cyclohexanone Cyclohexanone Indu
G12 123911 1,4-Dioxane 1,4-dioxane Indu
G13 58082 Caffeine Caffeine PPCL
G14 117817 Bis(2-ethylhexyl)phthalate (DEHP) DEHP Plast
G15 627930 Dimethyl adipate Dimethyl adipate Indu
G18 115866 Triphenyl phosphate TPPA Indu
G20 2008584 2,6-Dichlorobenzamide BAM Pest
G21 3622842 Benzenesulfonamide, N-butyl- BBSA Plast
G22 119619 Benzophenone Benzophenone PPCL
G24 126863 2,4,7,9-Tetramethyl-5-decyne- 4,7-diol TMDD Indu
G25 87412 1(3H)-Isobenzofuranone 1(3H)-isobenzofuranone Indu
G26 77732093 Oxadixyl Oxadixyl Pest
G27 131113 Dimethyl phthalate DMP Plast
G29 101371 2,4,6-Triallyloxy-1,3,5-triazine TTT Indu
G30 115968 Tri-(2-chloroethyl) phosphate Tri-(2-chloroethyl) phosphate Indu
G32 122394 Diphenylamine Diphenylamine Pest
G35 1241947 2-Ethylhexyl diphenyl phosphate 2-ethylhexyl diphenyl phosphate Indu
G38 298464 Carbamazepine Carbamazepine PPCL
G40 128370 Butylated hydroxytoluene BHT PPCL
G42 131577 Benzophenone-3 Benzophenone-3 PPCL
G43 94133 Propylparaben Propylparaben PPCL
G44 314409 Bromacil Bromacil Pest
G46 96764 2,4-Di-tert-butylphenol 2,4-DTBP Indu
G47 132649 Dibenzofuran Dibenzofuran Indu
G48 77907 Tributyl acetylcitrate ATBC Plast
G49 2440224 Drometrizole Drometrizole PPCL
G50 93049 2-Methyoxynaphthalene Nerolin Indu
Table 4.6    Compounds detected by LC-MS screen not present in standard suites.
Ranking CAS Number Analyte Short name Use code *
L06 298464 Carbamazepine Carbamazepine PPCL
L07 2971906 Clopidol Clopidol PPCL
L09 210880925 Clothianidin Clothianidin Pest
L11 723466 Sulfamethoxazole Sulfamethoxazole PPCL
L12 84057841 Lamotrigine Lamotrigine PPCL
L18 17254807 Chloridazon-desphenyl-methyl CDM Pest
L19 56038132 Sucralose Sucralose PPCL
L21 133855988 Epoxiconazole Epoxiconazole Pest
L22 188425856 Boscalid (Nicobifen) Boscalid Pest
L23 138261413 Imidacloprid Imidacloprid Pest
L25 120068373 Fipronil Fipronil Pest
L27 63741 Sulfanilamide Sulfanilamide PPCL
L28 115286 1,4,5,6,7,7-Hexachloro-5- norbornene-2,3-dicarboxylic acid Chlorendic acid Indu
L33 27203925 Tramadol Tramadol PPCL
L36 142459583 Flufenacet (Fluthiamide) (BAY FOE 5043) Flufenacet Pest
L38 5915413 Terbuthylazine Terbuthylazine Pest
L39 239110157 Fluopicolide Fluopicolide Pest
L41 107534963 Tebuconazole (Terbuconazole) Tebuconazole Pest
L42 153719234 Thiamethoxam Thiamethoxam Pest
L43 137586 Lidocaine (Diocaine) Lidocaine PPCL
L44 120983644 Desthio-prothioconazole Desthio-prothioconazole Pest
L45 2163691 Cycluron Cycluron Pest
L46 87674688 Dimethenamid (SAN 582H) Dimethenamid Pest
L47 422556089 Pyroxsulam Pyroxsulam Pest
L48 64902723 Chlorsulfuron Chlorsulfuron Pest
L49 21087649 Metribuzin Metribuzin Pest

Table 4.6 shows that the situation is similar for the LC-MS screen with 27 of 50 compounds detected not present in the standard suites. These are mainly pesticides, including TPs, and PPCL compounds.

Comparison of LODs[edit]

LODs for the top 50 compounds for the GC-MS screen are shown in Table 3.1. These are predominantly 0.01 μg/L with higher limits for four compounds, the industrial compound TMDD, the food additive BHT, and the plasticisers BBSA and DEHP.

LODs for the top 50 compounds for the LC-MS screen are shown in Table 3.2. These are predominantly an order of magnitude lower at 0.001 μg/L increasing for perfluorinated compounds, and also for the PPCLs sucralose, sulphanilamide and sulfamethoxazole, and the pesticides boscalid, trietazine and mecaprop.

The ranges of LODs for Environment Agency quantitative analytical suites are shown in Table 4.3. These are of a similar order of magnitude to the LC-MS method with higher limits for PAHs and difficult compounds, such as the pesticides chlormequat, glyphosate and metaldehyde.

Confidence[edit]

A third element must be the increased confidence in identification and quantification provided by the quantitative suites.

Case study on pesticides[edit]

Jenkins and Davy (2016)[2] report on the comparison between quantitative suites and the target based LC-MS method for pesticides in six Catchment Sensitive Farming (CSF) examples. Key determinands in this study were propyzamide, metazachlor, atrazine, diazinion, ethofumasate, MCPP, simazine, mecoprop, carbetamide and 2,4-D.

They found that overall the methods produced comparable results. There was a higher degree of scatter in the relationship at lower concentrations indicating that one or both of the methods was less accurate for concentrations close to the LOD. The target based LC-MS method was less precise and it was assessed that there was an increased risk of false positives. However the target based method had a lower LOD for many of the compounds used in this example.

References[edit]

  1. MANAMSA, K, CRANE, E, STUART, M, TALBOT, J, LAPWORTH, D, and HART, A. 2016. A national-scale assessment of micro-organic contaminants in groundwater of England and Wales. Science of the Total Environment, 568, 712–726
  2. JENKINS, J, and DAVEY, A. 2016. A comparison of the direct analysis and LC-MS methods for monitoring pesticides in CSF catchments. WRc Report UC111343.03 for the Environment Agency.