Environmental Fate and Effects 

of the Lampricides TFM and 

Niclosamide

1

Briefing for the Enviromental Protection Agency

November 5, 2012
Lampricide Fate and Effects

• TFM

– Hubert, T. D. 2003. Environmental Fate and 

Effects of the Lampricide TFM: A Review. 

Journal of Great Lakes Research. 

29(Supplement 1):456-474.

• Niclosamide

– Dawson, V. K. 2003. Environmental Fate and 

Effects of the Lampricide Bayluscide: A 

Review. 29(Supplement 1):475-492.

2
EPA Assessment

• Human Health 

– Moderate to low toxicity

– Risk of exposure low

– No developmental toxicity

– No carcinogenicity

– No mutagenicity

• Conclusion

– No risk to general population

3
EPA Assessment

• Environmental Fate and Effects

– Chemically stable and persistent

– Some impacts to aquatic organisms

– Aquatic communities recover quickly

• Conclusions

– Risks reduced by

• Flushing action of stream

• Rapid repopulation from non-treated portions of 

stream

• Treatment on 3-5 year cycles

4
• Additional studies

– TFM

• Photodegradation

– Niclosamide

• Photodegradation

• Aerobic aquatic metabolism

• Anaerobic aquatic metabolism

5
OH

CF3

NO2

TFM Niclosamide

C

O

N

H

Cl

OH

Cl

NO2

6
Environmental Fate - Hydrolysis

• TFM

– Resistant to hydrolysis 

– Half-lives over 1400 days

• Niclosamide

– Resistant at basic pH 

– Half-life at pH 5 – 120 hours 

7
Photodegradation

pH TFM t1/2 (h) Niclosamide t1/2 (h)

5 11.6 7.2

7 4.15 11.7

9 3.36 30

8
Photodegradation

• Degradation products

– Low molecular weight organic acids

• Substituted 2, 3, and 4 carbon organic acids 

(maleic, oxalic, glyoxylic)

– Carbon dioxide

9
Binding to sediment

• Milakokia River 1997

– Sandy sediment

– Chemical fell below detection in 24 to 96 

hours

• Carp River and Fish Creek 2010

– Slight organic content sediment

– Same result: below detection in 24 to 96 

hours

10
Aerobic/anaerobic degradation

• TFM

– Half-lives 2 to 5 days

– RTFM, incorporation in high MW organic 

matter, polymers, humic or fulvic acids 

• Niclosamide

– Half-lives ~ 5 days aerobically; 0.65 to 2.79 

days anaerobically

– Small carbon compounds and incorporation 

into humin

11
Metabolism

OH

CF3

NO2

OGlu

CF3

NO2

transferase

glucuronyl

12
Metabolism

• Aquatic Insects

– TFM: Sulfation, glucuronidation

– Niclosamide: hydrolysis, conjugation

• Fish

– TFM: glucuronidation

– Niclosamide: glucuronidation, sulfation

• Mammals

– TFM: glucuronidation, reduction and acetylation, 

sulfation

– Niclosamide: glucuronidation

13
Uptake and Elimination

• Species studied - green algae, aquatic plants, 

isopods (sowbug), amphipods, crayfish, mayfly, 

caddisfly, annelid worms (leeches), snails, fingernail 

clams, and fish

• Half-lives ranged from 7 hours to 18 days

– Exception: annelid worms, t1/2 = ~ 221 days

• Bioconcentration factors (BCF) for whole body and 

tissues ranged from less than 1 to ~ 62

– Dioxin: BCF 5,840 in fathead minnow

14
Effects on Plants

• TFM

– Aquatic Plants

• Toxic at >15 mg/L

• Effects at 5 mg/L but plants recover

– Green Algae/Blue-green Algae

• Reduction in growth at < 10 mg/L

• Minor reductions in pH and dissolved oxygen

• Niclosamide

– No effects at treatment concentrations

15
• Fish

– TFM 

• Toxicity low to high depending on species

• Generally high margins of selectivity

– Niclosamide

• Highly toxic to most fish

• Margin of selectivity lower than TFM

16
• American eel

– Tested elvers

– Highly resistant to TFM or TFM/niclosamide 

mixtures

– 4 to 7 times MLC for sea lamprey

17
Effects on Aquatic Invertebrates

• TFM

– Slightly to moderately toxic

• Niclosamide

– Slightly to highly toxic

18
• Endangered Hungerford’s crawling water 

beetle

– Surrogate Haliplus spp tested

– Adults and larvae

– Survival unaffected at up to 3.9X MLC

– Adults appeared to avoid chemical by 

crawling out of water

19
• Mussels

– Giant floater, fragile papershell, pink 

heelsplitter, black sandshell, snuffbox, ellipse

– At concentrations of TFM required to kill 

lampreys mortality is minimal. Adults, 

juveniles, glochidia are resistant; recruitment 

not affected. 

– TFM/1% niclosamide caused some mortality

20
• Native lamprey study

– Lampetra, Ichthyomyzon, Petromyzon

– No significant difference in median lethal 

concentration

– Slight difference in MLC between Lampetra 

and Petromyzon

– Some lampetra will survive treatments

– Native lamprey will be impacted

21
Effects on Reptiles and Amphibians

• TFM

– Turtles

• No effects

– Frogs

• Effects that vary depending on species, stage of development, 

and route of exposure

– Mudpuppies

• Reports of sensitivity and population declines

• UMESC study – adults not affected (2.4X MLC)

• Juveniles < 100 mm are less resistent to TFM (1.5X MLC)

• Juveniles more sensitive to TFM/niclosamide mixture

• Niclosamide

– Turtles

• No effects at treatment concentrations

– Frogs

• No effects at treatment concentrations

22
Effects on Birds

• TFM

– Oral toxicity ranged from 250 mg/kg to 546 mg/kg body 

weight

– Water concentrations of between 15 mg/L and 50 mg/L

• Uncoordination and lethargy depending on length of exposure

• Niclosamide

– Oral toxicity ranged from 500 mg/kg to over 2000 mg/kg

– Water concentration of 0.10 mg/L

• Produced slight uncoordination in one animal

23
• Common tern – St. Marys River

– Risk from eating dead larvae

– In lab exposed larvae to bayer granular and 

wettable powder

– Analyzed for niclosamide

– 3.49 ppb tissue concentration

– Low acute toxicity exposure risk

24
• Piping plover – Endangered

– Estimate exposure risk

• Residues in water and caged insects

– Likely exposure for adults 85X below NOEC

– Likely exposure for chicks 17X below NOEC 

25
Effects on Mammals

• TFM

– Oral toxicity 141 to 387 mg/kg

– Dermal toxicity: > 2000 mg/kg

– Moderate dermal and eye irritation

• Niclosamide

– Oral toxicity >5000 mg/kg

– Dermal toxicity >2000 mg/kg

– Inhalation toxicity 1.95 mg/L

– Mild eye irritation, no dermal irritation

26
Effects on Mammals

• TFM

– No effects to decreased body weights, increased liver 

weights, and reduced weights in offspring

– No cancer, mutations, developmental toxicity or 

increased tumor incidence

– No reproductive effects

• Niclosamide

– No effects to decreased body weights, increased liver 

weights, and reduced weights in offspring

– No cancer, mutation, developmental toxicity, or 

increased tumor incidence

– Abnormal sperm morphology in mice

27
Summary

• Effects transient

• Do not persist

• Relatively non-toxic

28
Questions

29