'Emerging’ Organic Contaminants and their

Potential Significance for the Agricultural

Recycling of Biosolids

Stephen Smith & Bradley ClarkeDepartment of Civil and Environmental Engineering

What’s the problem?

Over 50 million unique chemicals in CAS (Chemical Abstracts Service) database 143,000 registered in industrial use in EuropeAll potential biosolids contaminants that derive from industrial, urban and domestic sourcesEnvironmental and health concerns:Toxicity, mutagenicity, carcinogenicity,

endocrine disruption, developmental toxins, ecotoxicity, antibiotic resistance

Strategic Reviews of OCs in Sludge

• Smith 1994 FWR Report• Smith 1996 Agricultural Recycling of Sewage Sludge and

the Environment. CAB INTERNATIONAL• Smith 2000 Progress in Environmental Science 2• ICON 2001 Pollutants in Waste Water and Sewage

Sludge, Final Report to European Commission• Schowanek et al 2004 Reg Tox Pharm 40• Smith and Black 2006 Sources and Impacts of Past,

Current and Future Contamination of Soil - Organic Contaminants, Final Report to DEFRA

• Schowanek et al 2007 Reg Tox Pharm 49• Jensen et al 2007 Chemosphere 69• Smith 2009 Philosophical Transactions of the Royal

Society A 367, 3871-3872.

Behaviour in Soil-Water-Plant System

•Toxic compounds present in trace amounts•Three categories of behaviour:

• Rapid volatilisation• Rapid biodegradation and no persistence• Strong adsorption of persistent compounds

•Sludge Soil Plant Human (USEPA Pathway 1)

• No bioconcentration in crops detected (<0.01) • Negligible uptake = minimal human exposure

0

500

1000

1500

2000

2500

3000

1966 1976 1986 1996 2006

Co

nce

ntr

atio

ns

ng

g-1lip

id

DDT PCBs

BDEs PFOS

Trends in Environmental Exposure?

Norén et al. (2000) Chemosphere 40, 1111-1123 Karrman et al. (2007) Environ. Health Persp. 115, 226-230

Human Milk Concentrations

Hites (2004) Environ. Sci. Technol. 38, 945-956She et al. (2007) Chemosphere 67, S307-S317

Sensationalised badly designed biosolids research

promotes negative public perception

Sensationalised badly designed biosolids research

promotes negative public perception

Understanding the Risks

ContaminantPathwayReceptorEcological

1. Soil microbes2. Soil organisms3. Higher trophic animal4. Define receptors

Human1. Direct Exposure2. Plant uptake3. Animal uptake4. Water contamination

Biosolids amended soil

Food Chain Human Exposure

Key Questions

•Are there organic pollutants that may impact on the safe land application of biosolids?

•What are the likely candidates?

•How much research has been conducted internationally?

•What are the key research priorities to ensure the long-term sustainable management of biosolids?

List of Contaminants Reviewed

IncludedAntibiotics and pharmaceuticalsBenzothiazolesBisphenol AOrganotins (OTs)Polybrominated diphenyl ethers (PBDEs)Polychlorinated alkanes (PCAs)Polychlorinated naphthalenes (PCNs)Polydimethylsiloxanes (PDMS)Perfluorochemicals (PFCs)Phthalate acid esters (PAEs)Quaternary ammonium compounds (QACs)SteroidsSynthetics musksTriclosan (TCS) & triclocarban (TCC)

ExcludedChlorinated dioxins/furans (PCDD/Fs)Polyaromatic hydrocarbons (PAHs)Polychlorinated biphenyls (PCBs)Nonylphenol (NP)Linear alkyl benzene sulphonate (LAS)

Assessment Criteria

Soil persistencePotential risks to human food chainEcological bioaccumulationSoil ecotoxicityExtent and quality of the research

Biosolids Conc. Mean (Range) mg kg-1 DS

WWTP % Removal

Soil Persistence Half Life

Food Chain Possible, Uncertain or No

Bioaccumulation Yes, No or Likely

Ecotoxicity Yes, No or Uncertain

Research Numerous, Some or Few

Antibiotics & Pharmaceuticals

Development of antibiotic resistance (human health) Ecological consequences

Short residence time in aquatic environment

Longer persistence in soil (i.e., carbamazapine 21 months, plant uptake)

Many contain non-polar core and polar functional groupNorwegian Risk Assessment

Identified 14 of 1400 for further research

Sig. below PNEC US EPA Biosolids Survey

72 pharmaceuticals

Biosolids Conc. Low mg/kg

WWTP Unchanged/Unknown

Soil Persistence Unknown; generally reported in days

Food Chain Possible

Bioaccumulation No

Ecotoxicity Uncertain

Research More required

Drug (mg kg-1 dry soil)

Agricultural soil PEC Park areas PEC PNEC

Mesalazin 0.98 6.70 12

Ranitidin 0.04 0.30 5277

Sotalol 0.02 0.15 4095

Metoprolol 0.02 0.13 589

Atorvastatin 0.05 0.34 11

Tetracycline 0.01 0.08 8.8

Ciprofloxacin 0.04 0.29 26

Carisoprodol 0.10 0.68 24368

Gabapentin 0.06 0.39 20460

Benzothiazoles

2-Mercaptobenzothiazole MBT

2-Hydroxybenzothiazole OBT

Rubber vulcanizing agents Polymerisation of sulphur with rubber

Proposed German limit

MBT+OBT: 0.6 mg kg-1 DS

Lack of empirical data

No specific reason why it was chosen?

Aquatic toxicity

Studies indicate that these compounds are biodegradable

Biosolids Conc. Unknown

WWTP Unknown

Soil Persistence Unknown

Food Chain Uncertain

Bioaccumulation No

Ecotoxicity Uncertain

Research Small

Bisphenol A

Used in coatings of cans, plastics, dental fillings etc.Endocrine disruptor 1×10-6 less than 17β-estrodiol

Human exposure occurs in domestic environmentSig. reductions in WWTPRapidly dissipated in soilUnlikely to pose issue for biosolids reuse

Biosolids Conc. 0.28 (0.01 - ~ 325)

WWTP Up to 99%, biodegradation

Soil Persistence 3 days

Foodchain No

Bioaccumulation No

Ecotoxicity No

Research Small

Bisphenol A

Organotins

•Used since 1960s for industrial and agricultural purposes

• PVC stabliser• Fungicides• Insecticides• Wood preservative

•High toxicity observed in aquatic environment•Restricted use of TBT•More research required

Biosolids Conc. 0.86 (0.02 – 6)

WWTP >80% sedimentation

Soil Persistence < 2 months

Human Health Uncertain

Bioaccumulation Possible

Ecotoxicity Yes

Research Small

Tributyltin TBT

Phthalates acid esters

Biosolids Conc. 58 (0.26 – 3514)

WWTP Biodegradation (23 – 60%)

Soil Persistence <100 days

Foodchain No

Bioaccumulation No

Ecotoxicity No

Research Large

DEHP

•Used since 1950s as a plasticizer•Concern as EDC•Degrades during WWTP•Degrades in soil•Unlikely to enter food chain

020406080

100120140160180

Con

cent

ratio

n m

g kg

-1dw

Polybrominated diphenyl ethers (PBDEs)

Recently included as UN POPEnvironmental contaminant

Biosolids Conc. 1.36 (0.01 – 4.69)

WWTP Sedimentation

Soil Persistence 20 years

Food chain Yes

Bioaccumulation Yes

Ecotoxicity Uncertain

Research Large

PBDEs0

200

400

600

800

1000

1200

1400

1600

1800

1981 1986 1991 1996 2001

Con

cent

ratio

n ng

g-1

lipid

Lake Ontario Lake Michigan Lake Huron

Used as fire retardantElectronics

Norstrom et al. (2002) Env. Sci. Techol. 36, 4783-4789 North American Great Lakes ecosystem in 2000 was determined by analysis of herring gull eggs analysing archived samples between 1981 and 2000

Polybrominated diphenyl ethers (PBDEs)

Recently included as UN POPEnvironmental contaminant

Biosolids Conc. 1.36 (0.01 – 4.69)

WWTP Sedimentation

Soil Persistence 20 years

Food chain Yes

Bioaccumulation Yes

Ecotoxicity Uncertain

Research Large

PBDEs

Used as fire retardantElectronics

0

0.5

1

1.5

2

2.5

3

3.5

4

Con

cent

ratio

n m

g kg

-1dw

Polychlorinated alkanes

Produced since 1930sClass of industrial chemicals comprising chlorinated straight-chain hydrocarbonsApplications include:

Extreme pressure lubricant additives Plasticizers Flame-retardants Paint additives

Analytical challenge 10,000+ isomersExtremely high concentrations reportedDetected in humans Similarity to United Nations POPs

Biosolids Conc. 910 (1.8 – 9700)

WWTP Unknown

Soil Persistence Unknown

Food chain Yes

Bioaccumulation Yes

Ecotoxicity Uncertain

Research Small

Short chain PCAs – C10-13

Medium chain PCAs – C14-17

Long chain PCAs – C18-30

Concentrations 1000 times higher

than PCBs

Polychlorinated naphthalenes

Used since early 1900sPrecedes/parallels PCBsApplications include

Dielectric fluids Engine oil additives Electroplating Wood preservatives Lubricant Dye production

Voluntary phased out in USA in 1970s1990s production ~ 150000 tonnesUnited Nations POPs candidateDioxin-like toxicity

Biosolids Conc. 0.044 (0.001 – 0.19)

WWTP Unknown; sedimentation

Soil Persistence Unknown

Food chain Yes

Bioaccumulation Yes

Ecotoxicity Uncertain

Research Small

Polydimethylsiloxanes – PDMS

Man-made organosilicone polymerWidely used in industrial applications and consumers products including:

Textiles treatment Household Personal care products Antifoam for food processing &

WWTPLow toxicityRapid abiotic degradationLargely removed through WWTP

94% unchanged

Biosolids Conc. 632 (122 – 5155)

WWTP Sedimentation (94%)

Soil Persistence 28 days

Food chain No

Bioaccumulation No

Ecotoxicity No

Research Good understanding

n ranges between 100 and >10000

Perfluorochemicals (PFOS & PFOA)

Accumulating in humansWidely detected in environmentUsed to make products resistant to heat, oil, stains, grease and waterCommon applications include:

Non-stick cookware Breathable membranes Stain-resistant carpets & fabrics Fire fighting foams Surfactants

Increases during WWTP Found in sediment and effluent

Recently included as UN POPRestrictions introduced (PFOS - Directive 2006/122/EC and under review as WFD PHS)

Biosolids Conc. 0.20 (0.01 – 3.12)

WWTP Increasing; in effluent & sludge

Soil Persistence Unknown

Food chain Yes

Bioaccumulation Yes

Ecotoxicity Uncertain

Research More required

Perfluorooctanoic acid PFOA

Perfluorooctane sulphonatePFOS

Quaternary Ammonium Compounds

Cationic surfactants (many)Commonly applications:

Fabric softeners, hair conditioners, disinfectants, biocides, emulsifiers, wetting agents

Source control of DTDMAC as aquatic toxinRelaced by DEEDMAC as more biodegradableLink to antibiotic resistance?

Biosolids Conc. Mean (Range)

WWTP Sedimentation &biodegradation

Soil Persistence 17 - 40 days

Food chain No

Bioaccumulation No

Ecotoxicity No

Research Few

R1-4 represent alkyl or aryl substituent’s

0

1000

2000

3000

4000

1991 1992 1993 1994

DTD

MAC

Con

cent

ratio

n m

g kg

-1dw

DTDMAC: ditallow dimethylammonium chlorideDEEDMAC: diethyl ester dimethylammonium chloride

Steroids

Humans primary source to WWTP Natural and synthetic Released as inactive polar conjugates

Female hormones degrade rapidlyHormone precursors regularly detected US EPA survey e.g. cholesterolUnlikely to be problematic for biosolids land applicationAnalytical problems

17 α-ethinyloestradiol

Biosolids Conc. Varied

WWTP High biodegradation

Soil Persistence Days

Human Health No

Bioaccumulation No

Ecotoxicity No

Research Small

17α-oestradiol oestrioloestrone

Synthetic Musks

Inexpensive substitutes for natural musks used since 1930sOriginal nitromusks toxic (15%)Replaced with polycyclic musks (85%)PECs < PNECsProposed German limits in sludge

Biosolids Conc. 14 (1.9 – 81)

WWTP Sedimentation & biodegradation

Soil Persistence Unknown

Food chain No

Bioaccumulation No

Ecotoxicity No

Research More required

AHTN

HHCB

0102030405060708090

100

Con

cent

ratio

n m

g kg

-1dw

Triclosan and Triclocarban

Widely used antimicrobials in personal care products, including:

Shampoos Soaps Cosmetics Skin-care lotions Creams Mouth rinses Toothpaste

Typical concentration 0.1 to 0.3% (w/w)

Triclosan

Triclocarban

Biosolids Conc. 24 (0.19 – 441)

WWTP Sedimentation & biodegradation

Soil Persistence <1 year

Food chain No

Bioaccumulation Yes

Ecotoxicity Yes

Research Small

0102030405060

mg

kg-1

dw

Triclosan Triclocarban

Typical Concentrations

0.01

0.1

1

10

100

1000

10000

Con

cent

ratio

n m

g kg

-1dw

•Higher than bulk chemicals •3 magnitudes higher than PCBs

Relatively high concentrations compared to other POPs

Very low concentrations

POPsBulk ChemicalPersonal Care

Persistence Food chain Ecological Soil Ecotoxicity Research Score2 – Yes

1 - Uncertain0 – No

2 – Possible1 - Uncertain

0 - No

2 - Yes1 - Possible

0 - No

2 - Yes1 - Uncertain

0 - No

3 - Lack of data2 - Few studies 1 - Consistent

0 - Many & similar

( /11)

Antibiotics 0 2 0 1 2 5

Benzothiazoles 1 1 0 1 3 6Bisphenol A 0 0 0 0 2 2Organotins 1 1 2 1 2 7Phthalates 0 0 0 0 1 1PBDEs 2 2 2 1 0 7PCAs 2 2 1 1 3 9PCNs 2 2 1 1 3 9Siloxanes 0 0 0 0 1 1PFCs 2 2 2 1 3 10QACs 0 0 0 0 2 2Steroids 0 0 0 0 2 2Synthetic Musks 1 0 1 0 1 3Triclosan 1 0 2 2 2 7Triclocarban 1 0 2 2 2 7

Assessment Matrix (somewhat subjective)

Assessment Scores

Score Contaminant

10 Perfluorochemicals (PFOS, PFOA)

9 PCAs; PCNs7 Organotins; PBDEs; Triclosan; Triclocarban6 Benzothiazoles5 Antibiotics and pharmaceuticals3 Synthetic musks2 Bisphenol A; QACs; Steroids1 Phthalates; Siloxanes

Key Recommendations

1.Long-term vigilance• Assessment, monitoring and research

2.Empirical measurements• Concentrations, fate and impacts

3.High concentration of PCAs• Risk to health due to POP characteristics?

4.PFCs have a unique chemistry for a UN POP • Potential environmental mobility?