# APPENDIX D:

Bibliography of Microcosm and Meso cosm Studies and Criteria Used to

Screen Studies for Analysis of Atrazi ne Risks to Aquatic Plant Communities

(49 pages)

1

# UNITED STATES ENVIRONMENTAL PROTECTION AGENCY

WASHINGTON D.C., 20460

OFFICE OF

CHEMICAL SAFETY AND

POLLUTION PREVENTION



# Date : August 25, 2011

Chemical: Atrazine

PC Code: 080803

DP Barcode : 382803

MEMORANDUM

Subject: Bibliography of Microcosm and Mesocosm Studies and Criteria Used to Screen

Studies for Analysis of Atrazine Risks to Aquatic Plant Communities

TO: Melanie Biscoe, Chemical Review Manager

Anne Overstreet, Team Leader

Pesticide Re-evalua tion Division (7508P)

Office of Pesticide Programs

From: Michael Lowit, Ph.D., Ecologist

Anita Pease, Associate Division Director

Dana Spatz, Branch Chief

Brian Anderson, Branch Chief

Environmental Fate and Effects Division (7507P)

Potential effects of atrazine on plant comm unities have been evaluated using available

microcosm and mesocosm studies (referred to as co sm studies hereafter). Initially, a literature

search was conducted to identify a set of cosm studi es that was ultimately used in preparation of

the 2003 Interim Reregistration Elig ibility Decision (IRED, U.S. EPA, 2003). Subsequent to the

IRED, Scientific Advisory Panel (SAP) meetings we re held on scientific issues associated with

the ecological significance of atrazine on pr imary producers in surface water streams in

December, 2007 and May, 2009. Documents from th ese SAPs can be found at the following url:

http://www.epa.gov/oscpmont/sap/meetings/2007/index.htm

http://www.epa.gov/oscpmont/sap/meetings/2009/index.htm

One recommendation of these SAPs was to consid er a number of additional cosm studies, many

of which were published since the 2003 IRED, for the evaluation of potential effect levels of

atrazine on aquatic plant communities. Cosm studies included in the 2003 IRED and those

recommended by the SAP were considered in the current analysis.

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# First, all studies were prescr eened. A study was excluded from fu rther consideration if four

criteria were not met: (1) treatments were exposed to only atrazine, that is, not mixtures or multiactive ingredients, (2) exposure co ncentrations were reported, (3) m easured effects were specific

to aquatic plant communities (defined as two or more species), and (4) the study was written in

English.

Studies that met the basic elements of the prescree n criteria were further screened using a quality

criteria. The accepted studies were then used as the basis for deriving the initial atrazine Level

of Concern (LOC). The acceptance criteria are included in Attachment 1 and were intended to

identify studies with minimal study design and performance elements to allow greater confidence

in the study results. Criteria incl uded basic elements such as use of controls and use of at least

two replicates per treatment group. The criteria were derived using peer reviewed sources from

U.S. EPA, SETAC (Society of Environmen tal Toxicology and Chemistry), and OECD

(Organization for Economic Co-operation and Development) (Giddings et al. 1999; OECD,

2004; U.S. EPA, 2004).

A total of 35 cosm studies were originally incl uded in the 2003 IRED, and an additional 38 cosm

studies were identified in the May 2009 SAP for a total of 73 studies. Applying the prescreening

and acceptance criteria to the 73 st udies resulted in including 31 of the original 35 studies

presented in the IRED and 15 of the 38 studies recommended for consid eration in the May 2009

SAP report (46 total studies). Citations of all 73 cosm studies considered are in Attachment 2

.

A total of 87 endpoints were used in the analysis to develop the level of concern for atrazine.

These endpoints came from the 46 studies that passed the prescreening and acceptance criteria.

These endpoints are depicted in Figure 1 . Figure 1 distinguishes effects endpoints (blue

squares) from no effect endpoints (hollow triang les). Effects observed in the cosm studies

included changes in aquatic plant biomass, chlorophyll a concentration, phot osynthesis rate ( 14 

# C

uptake, oxygen production), and shifts in aqua tic plant community st ructure (e.g. species

composition and diversity) re lative to a control.

Effects in the cosm studies were scored using a binary effect/no effect score. In previous

analyses, the cosm studies were as signed Brock scores, which is a 5-point effects scoring system.

A Brock score of 1 was assigned to studies that did not produce an effect and a Brock score of 5

was assigned to studies that produced clear effect s without recovery. Studies with Brock scores

of 1 (no effect) or 2 (slight or transient effect) were distinguishe d from studies assigned 3 (clear

effect with recovery) or higher fo r the LOC analysis. Functionall y, the binary effects scoring is

identical to the manner in which Brock scores were used (Brock scores of 1 and 2 were

considered no effects and Brock scores of 3 or hi gher were considered to be effects). However,

all Brock scores (particularly thos e with a score of “2” indicating s light or transient effects) were

re-evaluated to ensure that each endpoint was categorized into the appropriate “effect” or “no

effect” group. Using a binary effect/no effect system was considered to be more clear and

transparent, which is the reason for adopting it for this analysis. A summary of all cosm

endpoints used in the analysis is in Attachment 3.

3

# Figure 1: Exposure duration and average atrazine concentrations for endpoints from cosm studies

that met the prescreening and acceptance criteria. Blue squares are endpoints with effects;

hollow red triangles are endpoints with no effects. 0.01

0.1

1 10 100 1000 10000

1 10 100 1000Average Study Concentration (ug/L atrazine)



# Exposure duration (days) Effect

No Effect



# 4

# Attachment 1. Criteria for Acceptance and Review of Atrazine Aquatic Micro/Mesocosm

Open Literature Study Reviews

In an effort to address recommendations from the May 12-14, 2009 Scientific Advisory Panel

(SAP) on Scientific Issues Associated with “The Ecological Significance of Atrazine Effects on

Primary Producers in Surface Water Streams in th e Corn and Sorghum Growing Regions of the

United States (Part II)”, EFED has developed qu ality criteria specific fo r the re-evaluation of

atrazine aquatic micro- and meso-cosm (cosm) studi es that were used as a basis for deriving the

initial atrazine Level of Concern (LOC). These same criteria we re also applied to the review of

38 additional atrazine cosm studies, which we re provided to EPA by an SAP member as

Appendix 2 of the SAP report, and would be appl ied to any new atrazine cosm data that the

Agency considers based on the best available information.

These criteria were derived based on informati on contained in the Community Level Aquatic

System Studies-Interpretation Criteria (CLASSIC) Society for Environmental Toxicology and

Chemistry (SETAC) publication (G iddings et al., 1999), as well as the 2004 Draft Organization

of Economic Cooperation and Development (OECD) Guidance Document on Simulated

Freshwater Lentic Field Tests (Outdoor Microcosms and Mesocosms) (OECD, 2004). While the

study acceptance and evaluation criteria describe d below are based on available guidelines for

interpretation of community-level aquatic toxici ty data, it is importa nt to note that best

professional judgment is necessary to ultimately de termine the appropriate use of atrazine cosm

data in defining the LOC. The acceptance criteria should be used as a first screen to determine

the validity of the study, whereas the evaluation criteria should be applied in the context of the

entire study design and quality, rather than as abso lute and independent measures of acceptance.

The approach used to derive the LOC for atrazine is unique in that it makes use of the robust set

of atrazine cosm data to identify various e xposure-duration concentra tions where effects are

observed in primary producers of the aquatic pl ant community. Therefore, the traditional

approach of using a pre-defined LOC, as sp ecified in the Agency’s Overview Document

(USEPA, 2004), with a specific exposure concen tration and endpoint value, is not used for

atrazine. The aquatic cosm acceptance and review criteria specified belo w are specific for only

atrazine because derivation of the LOC for this chemical is dependent on the identification of

exposure-concentration profiles where aquatic plant community-l evel effects are observed and

not on the identific ation of a single endpoint value.

Study Acceptance Criteria:

A study would be rejected as invalid, if any of the following accepta bility criteria are not

met:

1. Controls

A. Controls must be present a nd run concurrent with the study.

B. The presence of other stressors (physical, chemical, biological) in

controls/treatments must not be at levels that would be expected to compromise the

interpretation of atrazine (degra dates) as the causal stressor.

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# 2. Quantification of Exposure

A. The amount of test material applied and the exposure concen tration in the water

column should be determined analytically at the start of exposur e (t=0). Minimally,

nominal exposure concentrations of atrazine must be provided.

3. Experimental Design

A. At least two replicates per treatment a nd controls must be included regardless of the

statistical method used (e.g., regression, hypothesis testing).

B. If a solvent is used, it must be < 0.5 m l/L in static-renewal or static testing or <0.1

ml/L in flow-through testing and at the same concentration across treatments and

solvent and/or negative controls.

4. Statistical Methods and Data Interpretation

A. If a regression-based ap proached is used, at least th ree treatments (with a minimum

of two replicates/treatment) in addition to the controls must be tested. In the event

that two replicates/treatment are not tested, the study design must contain a

minimum sample size “N” of 5 including th e control in order to fit a nonlinear

regression curve.

B. Statistical analysis of the data (univariate and/or multivariate) including numerical

and/or graphical presentation of the results must be clearly descri bed and presented.

Study Evaluation Criteria:

If a study passes the acceptability criteria stip ulated above, further e valuation of the study

results relative to study performance and in terpretation of the effects data will be

conducted according to the following evaluation criteria:

1. Controls

A. Ideally, no detectable atrazine and/or de gradate concentrations should be present in

the controls. Atrazine leve ls in control water, based on measurements during the

study or on other information, should be “negligible or low enough” such that

conclusions regarding atrazine effects concentrations ar e not compromised. It is

expected that determination of what is considered “negligible or low enough” will

involve some level of interpretation regard ing effects observed at treatment levels

relative to the control. Factors to be c onsidered in determining whether atrazine

levels are “negligibl e” include, but are not limited to : (1) dose-res ponse within the

same study; (2) magnitude of contaminati on relative to effects levels in other

studies under similar environmental c onditions; and (3) magnitude of control

contamination relative to effects in the study being evaluated. It should be noted

that studies with chemical contamination in controls would normally be invalidated

under the Agency’s review process; however , these studies are being considered as

part the atrazine cosm review because: (1) data from these studies are being used in

a weight-of-evidence approach as part of a larger data set to identify the occurrence

of effects associated with various atrazine concentration-durati on profiles; (2) low

levels of atrazine are not uncommon in na tural waters and may occur in field study

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# control samples, regardless of whether its presence was evaluated; and (3) these

studies are not being used to sa tisfy specific data requirements.

2. Quantification of Exposure

A. Analytical measurements should be documented and of sufficient quality (if

reported) so as to not compromise in terpretation of the study results (e.g., %

recoveries, blanks, QA standards, etc.).

B. Preferably, the amount of parent co mpound and principal degr adates (if reported)

should be quantified at regular time interv als throughout the study in both the water

column and sediment (pore water and bound residues). If such time-series

measurements are not provided, informa tion should be available to estimate

exposure time trends, such as a reported half-life from the study or time-trends from

similar systems.

3. Experimental Design

A. All exposure levels and controls shou ld be analyzed for chemical contaminants

(particularly pesticides), nutrients, pH, hardness, temperature, dissolved oxygen

(DO), and turbidity.

B. If a solvent is used, both a solvent and a negative contro l should be tested.

C. If DO is used as a measure of prim ary productivity, then those measurements

should be sufficient to characterize diurnal fluctuations and must be recorded at

relatively similar times across study units.

D. The purity of the test material should be stated.

E. Acclimation period should be described.

F. Source of the water, sediment and biot a and containers used in the study should be

clearly described.

G. How treatments are assigned to mesoco sms should be clearly described; ideally,

treatments should be assigned randomly.

H. Study designs should adequately desc ribe and evaluate/acc ount for potential

confounding effects of non-chemical stressors, e.g ., habitat condition, prey

availability, nutrient loading.

I. Controls should be representative of trea tment units and should describe the basis of

their selection.

J. Exterior mesocosm studies should incl ude a description of the weather during the

study and how water levels were maintained during the study.

K. Study should describe whethe r treatment units were screened, i.e ., covered to limit

immigration and emigration of biota.

L. Exposure regime should reflect the ob jectives of the study and should be based on

expected routes of entry of the chemi cal into aquatic systems and relevant

frequency and timing of the entry of the chemical.

M. The duration of the study should be appropriate to the li fe-cycle of the organisms of

interest and the time needed for their recovery if these are stated objectives.

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# 4. Statistical Methods and Data Interpretation

A. For hypothesis testing, sufficient information should be available from which to

evaluate the statistical power of the comparisons (e.g., minimum significant

difference that can be detected).

B. Regarding the description of statistical analysis based on mean values, information

on the variability within repl icates (i.e., statistics repr esenting the experimental

variation among replicates, reporting of th e standard deviation, etc.) should be

provided and considered in th e overall quality of the study.

5. Other

A . Where the review of a study indicates th at a departure from this document’s criteria

is scientifically warranted, the reviewer should provide the rationale for the action

taken.

References

Giddings et al. 1999. Community-L evel Aquatic System Studie s – Interpreta tion Criteria

(CLASSIC). SETAC Press.

Organization of Economic Cooperation and Deve lopment (OECD). 2004. Draft Guidance on

Simulated Freshwater Lentic Field Syst ems (Outdoor Microcosms and Mesocosms).

U.S. EPA. 2004. Overview of the Ecological Risk Assessment Process in the Office of

Pesticide Programs. Office of Prevention, Pe sticides, and Toxic S ubstances. Office of

Pesticide Programs. Washington, D.C. January 23, 2004.

8

# Attachment 2. Micro- and Mesocosm Study Citations

A. Studies Previously Used for Cosm Endpo int Selection that Met Usability Criteria

1. Berard, A., T. Pelte, et al. (1999a). Seasonal va riations in the sensitivity of Lake Geneva

phytoplankton community structure to atrazi ne. Archiv Fur Hydr obiologie 145(3): 277-

295. (MRID 48261103)

2. Brockway, D.L., P.D. Smith, and F.E. Stancil. (1984). Fate and effe cts of atrazine on

small aquatic microcosms. Bull. Envi ron. Contam. Toxicol. 32:345-353. (MRID

47543602)

3. Carney, C.E. (1983). The effects of atrazine and grass carp on fres hwater communities.

Thesis. University of Kansas, Lawrence, Kansas (MRID 47543604)

4. deNoyelles, F. Jr., and W.D. Kettle. (1980). Herb icides in Kansas waters – evaluations of

effects of agricultural runoff and aquatic weed control on aq uatic food chains.

Contribution Number 219, Kansas Water Resour ces Research Institute, University of

Kansas, Lawrence, Kansas (MRID 47543605)

5. deNoyelles, F., Jr., W.D. Kettle, and D.E. Sinn. (1982). The responses of plankton

communities in experimental ponds to atrazine , the most heavily used pesticide in the

United States. Ecology. 63 (5):1285-1293 (MRID 47543607)

6. deNoyelles, F. Jr., and W.D. Kettle. (1983). Site studies to determine the extent and

potential impact of herbicide contamination in Kansas waters. Contribution Number 239,

Kansas Water Resources Research Institute, University of Kansas, Lawrence, Kansas.

(MRID 47543606)

7. deNovelles, Jr., F., W.D. Kettle, C.H. From m, M.F. Moffett, and S.L. Dewey. (1989).

Use of Experimental Ponds to Assess th e Effects of a Pesticide on the Aquatic

Environment. Department of Systematic s and Ecology, University of Kansas.

Entomological Society of America. Miscel laneous Publications No. 75: 41 – 56 (MRID

47543608)

8. deNoyelles, F., S.L. Dewey, D.G. Huggins, and W.D. Kettle. (1994). Aquatic mesocosms

in ecological effects testing: detecting direct and indirect effects of pesticides. In:

Graney RL, Kennedy J.H., Rodgers J.H. Jr. (Eds.). Aquatic mescocosm studies in

ecological risk assessment. Lewis P ublishers, Boca Raton, FL. pp. 577-603 (MRID

47543609)

9

# 9. Detenbeck, N.E., R. Hermanutz, K. Allen, and M.C. Swift. (1996). Fate and effects of

the herbicide atrazine in flow-through wetland mesocosm s. Environ. Toxicol. Chem.

15:937-946 (MRID 47543610)

10. Dewey, S.L. (1986). Effects of the herbicid e atrazine on aquatic insect community

structure and emergence. Ecology. 67:148-162 (MRID 47543611)

11. Gruessner, B. and M.C. Watzin. (1996). Response of aquatic communities from a

Vermont stream to environmentally realistic at razine exposure in labo ratory microcosms.

Environ. Toxicol. Chem. 15:410-419 (MRID 47543613)

12. Gustavson, K. and S. Wängberg. (1995). Tolerance induction and succession in

microalgae communities exposed to copper and atrazine. Aquat. Toxicol. 32:283-302

(MRID 47543614)

13. Hamala, J.A. and H.P. Kollig. (1985). The effects of atrazine on periphyton communities

in controlled laboratory ecosystems. Chemosphere. 14:1391-1408 (MRID 47543615)

14. Hamilton, P.B., G.S. Jackson, N.K. Kaushik, and K.R. Solomon. (1987). The impact of

atrazine on lake periphyton communities in cluding carbon uptake dynamics using track

autoradiography. Environ. Poll. 46:83-103 (MRID 47543616)

15. Hamilton, P.B., G.S. Jackson, N.K. Kaushi k, K.R. Solomon, and G.L. Stephenson.

(1988). The impact of two applic ations of atrazine on the pla nkton communities of in situ

enclosures. Aquat. Toxi col. 13:123-140 (MRID 47543617)

16. Hamilton, P.B., D.R.S. Lean, G.S. Jackson, N.K. Kaushik, and K.R. Solomon. (1989).

The effect of two applications of atrazine on the water quality of freshwater enclosures.

Environ. Pollut. 60:291-304 (MRID 47543501)

17. Herman, D., N.K. Kaushik, and K.R. Solomon. (1986). Impact of atrazine on periphyton

in freshwater enclosures and some ecological consequences. Can. J. Fish. Aquat. Sci.

43:1917-1925 (MRID 47543502)

18. Johnson, B.T. (1986). Potential impact of sele cted agricultural chemical contaminants on

a northern prairie wetland: A microcosm evaluation. Environ. Toxicol. Chem. 5:473-

485. (MRID 47543503)

10

# 19. Jurgensen, T.A. and K.D. Hoagland. (1990). Eff ects of short-term pulses of atrazine on

attached algal communities in a small stream. Arch. Environ. Contam. Toxicol. 19:617-

623. (MRID 47543504)

20. Kettle, W.D. (1982). Description and analysis of toxicant-induced responses of aquatic

communities in replicated experimental ponds. Ph.D. Thesis. University of Kansas,

Lawrence, KS. (MRID 48273504)

21. Kettle, W.D., F. deNoyelles, B.D. Heacoc k, and A.M. Kadoum. (1987). Diet and

reproductive success of bluegill recovered from ex perimental ponds treated with atrazine.

Bull. Environ. Contam. Toxi col. 38:47-52 (MRID 47543506)

22. Kosinski, R.J. (1984). The effects of terrestr ial herbicides on the co mmunity structure of

stream periphyton. Environ. Pollut. (Series A). 36:165-189. (MRID 47543507)

23. Kosinki, R.J., and M.G. Merkle. (1984). The e ffect of four terrestrial herbicides on the

productivity of artificial stream algal comm unities. J. Environ. Qual. 13:75-82. (MRID

47543508)

24. Krieger, K.A., D.B. Baker, and J.W. Kramer. (1988). Effects of herbicides on stream

Aufwuchs productivity and nutrient uptake. Arch. Environ. Contam. Toxicol. 17:299-

306. (MRID 47543509)

25. Lampert, W., W. Fleckner, E. Pott, U. Sc hober, and K.U. Storkel. (1989). Herbicide

effects on planktonic systems of different co mplexity. Hydrobiologia. 188/189:415-424.

(MRID 47543511)

26. Lynch, T.R., H.E. Johnson, and W.J. Adam s. (1985). Impact of atrazine and

hexachlorobiphenyl on the structure and functio n of model stream ecosystems. Environ.

Toxicol. Chem. 4:399-413. (MRID 47543512)

27. Moorhead, D.L. and R.J. Kosinski. (1986). Effect of atrazine on the productivity of

artificial stream algal communities. Bu ll. Environ. Contam. Toxicol. 37:330-336.

(MRID 47543513)

28. Pratt, J.R., N.J. Bowers, B.R. Niederlehrer, a nd J. Cairns, Jr. (1988). Effects of atrazine

on freshwater microbial communities. Ar ch. Environ. Contam. Toxicol. 17:449-457.

(MRID 47543514)

11

# 29. Stay, F.S., Larsen, D.P., Katko, A., and Ro hm, C.M., (1985) Effects of Atrazine on

Community Level Responses in Taub Microc osms. Validation and Predictability of

Laboratory Methods for Assessing the Fate a nd Effects of Contaminants in Aquatic

Ecosystems, ATSM STP 865, T.P. Boyle, Ed., American Society for Testing and

Materials, Philadelphi a, pp. 75-90 (MRID 45087419)

30. Stay, E.F., A. Katko, C.M. Rohm, M.A. Fix, and D.P. Larsen. (1989). The effects of

atrazine on microcosms developed from four natural plankton communities. Arch.

Environ. Contam. Toxicol. 18:866-875. (MRID 47543515)

31. Van den Brink, P.J., E. van Donk, R. Gylstra, S.J.H. Crum, and T.C.M. Brock. (1995).

Effects of chronic low concentra tions of the pesticides chlorpyr ifos and atrazine in indoor

freshwater microcosms. Chem osphere. 31:3181-3200. (MRID 47543516)

B. Studies Previously Used for Cosm Endpo int Selection that Failed Usability Criteria

1. Carder, J.P. and K.D. Hoagland. (1998). Co mbined effects of alach lor and atrazine on

benthic algal communities in ar tificial streams. Environ. Toxicol. Chem. 17(7):1415-

1420. (MRID 47543603)

2. Fairchild, J.F., T.W. LaPoint, and T.R. Schw arz. (1994). Effects of a herbicide and

insecticide mixture in aquatic mesocosms. Arch. Environ. Contam. Toxicol. 27:527-533

(MRID 47543612)

3. Juttner, I., A. Peither, J.P. Lay, Al. Ketr up, and S.J. Ormerod. (1995). An outdoor

mescosm study to assess ecotoxicological e ffects of atrazine on a natural plankton

community. Arch. Environ. Contam. Toxicol. 29:435-441. (MRID 47543505)

4. Lakshminarayana, J.S.S., H.J. O’Neill, S.D. Jonnavithula, D.A. Legerand, P.H. Milburn.

(1992). Impact of atrazine-bearing agricultural tile drainage di scharge on pla nktonic drift

of a natural stream. Envir on. Pollut. 76:201-210. (MRID 47543510)

C. New Studies Incorporated into Analysis as Recommended by the Science Advisory

Panel

1. Berard, A., C. Leboulanger, et al. (1 999b). Tolerance of Oscillatoria limnetica

Lemmermann to atrazine in natural phytoplankton populations and in pure culture:

Influence of season and temperature. Arch ives of Environmental Contamination and

Toxicology 37(4): 472-479. (MRID 47543601)

12

# 2. Berard, A. and C. Benninghoff (2001). Pollu tion-induced community tolerance (PICT)

and seasonal variations in the sensitivity of phytoplankton to atra zine in nanocosms.

Chemosphere 45(4-5): 427-437. (MRID 48261101)

3. Boone, M. D. and S. M. James (2003). Interact ions of an insecticide, herbicide, and

natural stressors in amphibian community me socosms. Ecological Applications 13(3):

829-841. (MRID 48261104)

4. Diana, S. G., W. J. Resetarits, et al. (2000) . Effects of atrazine on amphibian growth and

survival in artificial aquatic communities. Environmental Toxicology and Chemistry

19(12): 2961-2967. (MRID 48261107)

5. Downing, H. F., M. E. Delorenzo, et al. ( 2004). Effects of the ag ricultural pesticides

atrazine, chlorothalonil, and endosulfan on South Florida microbial assemblages.

Ecotoxicology 13(3): 245-260. (MRID 48261110)

6. Knauert, S., B. Escher, et al. (2008). Mixtur e toxicity of three phot osystem II inhibitors

(atrazine, isoproturon, and diur on) toward photosynthesis of freshwater phytoplankton

studied in outdoor mesocosms. Envir onmental Science & Technology 42(17): 6424-

6430. (MRID 48261119)

7. Knauert, S., U. Dawo, et al. (2009). Effect s of Photosystem II Inhibitors and Their

Mixture on Freshwater Phytopl ankton Succession in Outdoor Mesocosms. Environmental

Toxicology and Chemistry 28(4): 836-845. (MRID 48261120)

8. Leboulanger, C., F. Rimet, et al. (2001) . Effects of atrazine and nicosulfuron on

freshwater microalgae. Environment In ternational 26(3): 131-135. (MRID 48261121)

9. McGregor, E. B., K. R. Solomon, et al. ( 2008). Effects of planting system design on the

toxicological se nsitivity of Myriophyllum spicatum and Elodea canadensis to atrazine.

Chemosphere 73(3): 249-260. (MRID 48261124)

10. Relyea, R. A. (2009). A cocktail of contaminants: how mixtures of pesticides at low

concentrations affect aquatic commu nities. Oecologia 159(2): 363-376. (MRID

48261129)

11. Rohr, J. R. and P. W. Crumrine (2005). Eff ects of an herbicide and an insecticide on pond

community structure and processes. Ecol ogical Applications 15(4): 1135-1147. (MRID

48261130)

12. Rohr, J. R., A. M. Schotthoefer, et al . (2008). Agrochemicals increase trematode

infections in a declining amphibian species. Nature 455(7217): 1235-1239. (MRID

48261131)

13

# 13. Seguin, F., J. C. Druart, et al . (2001a). Effects of atrazine and nicosulfuron on periphytic

diatom communities in freshwater outdoor lentic mesocosms. Annales De LimnologieInternational Journal of Li mnology 37(1): 3-8. (MRID 48273501)

14. Seguin, F., C. Leboulanger, et al. (2001b). Effects of atrazine and nicosulfuron on

phytoplankton in systems of increasing co mplexity. Archives of Environmental

Contamination and Toxicol ogy 40(2): 198-208. (MRID 48261134)

15. Seguin, F., F. Le Bihan, et al. (2002). A ri sk assessment of pollu tion: induction of

atrazine tolerance in phytoplankton communitie s in freshwater outdoor mesocosms, using

chlorophyll fluorescence as an endpoint. Water Research 36(13): 3227-3236. (MRID

48261133)

D. New Studies Recommended by the Science Ad visory Panel that Failed the Usability

Criteria

1. Berard, A., T. Pelte, et al. (1998). Charac terisation of phytoplankton from two limnic

systems contaminated by a herbicidal phot osynthetic inhibitor. The PICT method

(Pollution-Induced Community Tolerance): application and significance. Annales De

Limnologie-International Journal of Limnology 34(3): 269-282. (MRID 48273502)

2. Berard, A., U. Dorigo, et al . (2003). Comparison of the eco toxicological impact of the

triazines Irgarol 1051 and atra zine on microalgal cultures and natural microalgal

communities in Lake Geneva. Chemosphere 53(8): 935-944. (MRID 48261102)

3. Bouldin, J. L., J. L. Farris, et al. (2005). Evaluated fate and effects of atrazine and

lambda-cyhalothrin in vegetated and unvegetated microcosms. Environmental

Toxicology 20(5): 487-498. (MRID 48261105)

4. DeLorenzo, M. E., J. Lauth, et al. (1999). At razine effects on the microbial food web in

tidal creek mesocosms. Aquatic Toxi cology 46(3-4): 241-251. (MRID 48261106)

5. Dorigo, U. and C. Leboulanger (2001). A pulse -amplitude modulated fluorescence-based

method for assessing the effects of photosystem II herbicides on freshwater periphyton.

Journal of Applied Phycology 13(6): 509-515. (MRID 48261108)

6. Dorigo, U., X. Bourrain, et al. (2004). Seas onal changes in the se nsitivity of river

microalgae to atrazine and isoproturon along a contamination gradient. Science of the

Total Environment 318(1-3) : 101-114. (MRID 48261109)

7. Graymore, M., F. Stagnitti, et al. (2001). Impacts of atrazine in aquatic ecosystems.

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8. Guasch, H., I. Munoz, et al. (1997). Changes in atrazine toxicity throughout succession of

stream periphyton communities. Journal of Applied Phycology 9(2): 137-146. (MRID

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14

# 9. Guasch, H., N. Ivorra, et al. (1998). Co mmunity composition and sensitivity of

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10. Guasch, H. and S. Sabater (1998). Light history influences the sensitivity to atrazine in

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Environmental Pollution 157(1): 237-249. (MRID 48261135)17Attachment 3. Summary of Cosm Endpoints Used to EvaluatePotential Effects of Atrazine on Aquatic Plant CommunitiesReference(s)Initial TestConcentration(μg/L)Duration(d)Single /Constant /MultipleEcosystemResultsPlantGroupRecoveryCommentsEffect(Y/N)Carney, 1983;Kettle et al., 1987;deNoyelles et al.,1989; deNoyelleset al., 1994500365SingleMesocoms,experimentalpondsDecrease in coverby emerged,floating, andsubmergedaquatic plants(>90% decline inTypha; 100%decline in SAV).Macro> 1 yr (norecoveryobserved)From 805-d studywhere pondsformerly treatedwith formulatedproduct at 20 μg/Lwere increased to500 μg/L;exposureconcentrationsderived from graphduring the secondyear of the study.YCarney, 1983;Kettle et al., 1987;deNoyelles et al.,1989; deNoyelleset al., 1994;deNoyelles andKettle, 1980;Dewey, 198620365SingleMesocoms,experimentalpondsDecrease in coverby floating andsubmergedaquatic plants(40% decline inTypha; 50%decline in SAV;50% decline inNajas).Macro> 1 yr (norecoveryobserved)From 805-d study;studyconcentrationsfrom first year ofstudy.YdeNoyelles et al.,1982; deNoyelleset al., 198950063SingleMesocoms,experimentalpondsDecrease (> 90%decline) inphytoplankton14C-uptake andbiomass. 100%decline in SAV.Change(observed after 14days) in speciescomposition ofphytoplankton.PhytoandMacro> 63 d (norecoveryreported forshift in speciescomposition;recovery inphytoplanktonbiomass andproductionoccurred >3weeks)From 136 daystudy; according tostudy authors,ponds wereintenselymonitored for first63 days, thensampled monthlythereafter until day136; however,exposureconcentrationinformation is notavailable past 63days.Y18Reference(s)Initial TestConcentration(μg/L)Duration(d)Single /Constant /MultipleEcosystemResultsPlantGroupRecoveryCommentsEffect(Y/N)deNoyelles et al.,1989; Carney,1983100365SingleMesocoms,experimentalpondsDecrease in coverby emerged andsubmergedaquatic plants(75% decline inTypha; 80%decline in SAV).Macro> 1 yr (norecoveryobserved)From 805-d study;studyconcentrationsfrom first year ofstudy where pondswere dosed withatrazine at 100μg/L.YdeNoyelles et al.,1989; Carney,1983200340SingleMesocoms,experimentalponds75-80% decline inTypha; >90%decline in SAV.Macro> 1 yr (norecoveryobserved)From 805-d study;studyconcentrationsfrom second yearof study.YHamilton et al.,19878056MultipleLakeenclosure60% decrease indensity; 20%decrease innumber ofperiphytonspecies; 80%decrease inperiphytonbiomass. Change(shift observedafter 2nd day ofexposure) inspeciescomposition.Peri49-50 drecovery forperiphytondensity andbiomass; norecovery forperiphytonnumbers andshift in speciescomposition.Results from 1983study cited in thepaper.YHamilton et al.,198714056MultipleLakeenclosure60% decrease indensity; 30%decrease innumber ofperiphytonspecies; 75%decrease inbiomass. Change(shift observedafter 3rd day ofexposure) inspeciescomposition.Peri>56 drecovery forperiphytondensity andbiomass; norecovery forperiphytonnumbers andshift in speciescomposition.Results from 1982study cited in thepaper; nosignificant effectsin endpoints otherthan speciescompositionobserved althoughdecreases wereevident.Y19Reference(s)Initial TestConcentration(μg/L)Duration(d)Single /Constant /MultipleEcosystemResultsPlantGroupRecoveryCommentsEffect(Y/N)Hamilton et al.,198810096MultipleLakeenclosureChange inspeciescomposition (93%change inphytoplanktoncompositionoccurring on day49 of study).Phyto>323 daysDuration ofHamilton studieswas 323 days afterfirst atrazineapplication;however,measured atrazineconcentrationswere available onlyup to 96 days.Exposure profileincludes twoapplications ofatrazine at 100μg/L (35 daysapart).YHerman et al.,1986; Hamilton etal., 198910096MultipleLakeenclosure40% decrease inPOC at day 34;80% decline in14C-uptake at day57; 10% - 20%decrease in DO,periphytonbiomass (50%),chlorophyll (50%),productivity(70%), andcommunitycomposition(100% decreasein Cyanophyta).Increase in secchidepth (30%),dissolvedinorganic carbon(60%), and nitritenitrogen (100%).Peri90 d; 14 d;>294 d; >294d (POCrecovery at 99d;14C-uptakerecovery at135 d; speciescomp recoveryat >323 d)DO, secchidepth, anddissolvedinorganiccarbonrecovered bythe next spring(329 days); norecovery wasobserved forthe otherparametersevaluated.Duration ofHamilton studieswas 323 days afterfirst atrazineapplication;however,measured atrazineconcentrationswere available onlyup to 96 days.Exposure profileincludes twoapplications ofatrazine at 100μg/L (35 daysapart).Y20Reference(s)Initial TestConcentration(μg/L)Duration(d)Single /Constant /MultipleEcosystemResultsPlantGroupRecoveryCommentsEffect(Y/N)Stay et al., 198543053SingleMicrocosms,laboratoryTaub (picklejars)60-70% decreasein DO; 90%decrease in14Cuptake; <100%decrease inprimaryproductivity (wentnegative); and80% decrease inratio of14C tochl-a.Phyto> 53 d (norecoveryobserved)Daphnid bloomoccurred betweendays 18 and 35 ofthe study andstrongly interactedwith the effects ofthe atrazinetreatments. Onlyatrazine-relatedeffects thatoccurred prior tothe daphnid bloomon day 18 areconsidered. Fullduration of studywas 60 days withatrazine addition atday 7.YStay et al., 198582053SingleMicrocosms,laboratoryTaub (picklejars)60-70% decreasein DO; 90%decrease in14Cuptake; <100%decrease inprimaryproductivity (wentnegative); and80% decrease inratio of14C tochl-a.Phyto> 53 dDaphnid bloomoccurred betweendays 18 and 35 ofthe study andstrongly interactedwith the effects ofthe atrazinetreatments. Onlyatrazine-relatedeffects thatoccurred prior tothe daphnid bloomon day 18 areconsidered. Fullduration of studywas 60 days withatrazine addition atday 7.Y21Reference(s)Initial TestConcentration(μg/L)Duration(d)Single /Constant /MultipleEcosystemResultsPlantGroupRecoveryCommentsEffect(Y/N)Stay et al., 1985398053SingleMicrocosms,laboratoryTaub (picklejars)60-70% decreasein DO; 90%decrease in14Cuptake; <100%decrease inprimaryproductivity (wentnegative); and80% decrease inratio of14C tochl-a.Phyto> 53 dDaphnid bloomoccurred betweendays 18 and 35 ofthe study andstrongly interactedwith the effects ofthe atrazinetreatments. Onlyatrazine-relatedeffects thatoccurred prior tothe daphnid bloomon day 18 areconsidered. Fullduration of studywas 60 days withatrazine addition atday 7.YBrockway et al.,19841007SingleMicrocosms,lab stagnant40% decrease innet oxygenproduction.Phyto> 7 dEffect occurred atday 1; exposurelevels are nominal.YBrockway et al.,198450012SingleMicrocosms,lab stagnant90% decrease innet oxygenproduction.Phyto>12 dEffect occurred atday 1; exposurelevels are nominal.YBrockway et al.,1984500012SingleMicrocosms,lab stagnant100% decrease innet oxygenproduction.Phyto> 12 dEffect occurred atday 1; exposurelevels are nominal.YDetenback et al.,19961515ConstantArtificial flowthroughswampDecrease in DOand grossproductivity (23%decrease in DO;reduction in grossproductivity(p<0.05) notreported).Increase innutrients (15%increase in PO4;15% increase inammonium).PeriRecovery notreported.Atrazine detectedin the controlwetlands; durationof exposure is 15days.Y22Reference(s)Initial TestConcentration(μg/L)Duration(d)Single /Constant /MultipleEcosystemResultsPlantGroupRecoveryCommentsEffect(Y/N)Detenback et al.,19962543ConstantArtificial flowthroughswampDecrease inperiphytonrespiration andnet productivity(reduction inrespiration andnet primaryproductivity(p<0.05) notreported).PeriRecovery notreported.Atrazine detectedin the controlwetlands; durationof exposure is 43days.YDetenback et al.,19965032ConstantArtificial flowthroughswampDecrease(reduction in netproductivity (p<0.05)) notreported. Increasein nutrients (40%increase in PO4;100% increase inammonium).PeriRecovery notreported.Atrazine detectedin the controlwetlands; durationof exposure is 32days.YDetenback et al.,19967917ConstantArtificial flowthroughswampDecrease(reduction in netproductivity (p<0.05)) notreported. Increasein nutrients (50%increase in PO4;250% increase inammonium).PeriRecovery notreported.Atrazine detectedin the controlwetlands; durationof exposure is 17days.Y23Reference(s)Initial TestConcentration(μg/L)Duration(d)Single /Constant /MultipleEcosystemResultsPlantGroupRecoveryCommentsEffect(Y/N)Hamala and Kollig,198510014ConstantMicrocosm,lab flowingDecrease inprimaryproduction (100%reduction inproductivity(becamenegative); 25%reduction innumber ofspecies; 50%reduction inbiomass).Change inspeciescomposition (35%decrease inchlorophytaabundanceobserved at day14).Peri>14 d to > 21dPeriod of exposurewas 14 days with a21 day recoveryperiod followingexposure.YJohnson,1986100030SingleMicrocosm,lab stagnantDecrease inmacrophytebiomass (50%);primaryproduction (90%);increase inalkalinity (approx.2-fold).Slight decrease inpH (10%) andincrease inconductivity(20%).Macro>30 dAtrazineconcentrationswere notmeasured; nominalvalues were used.Effect occurred atday 2 (primaryproductivity) andday 30 (biomass;only measurementtime).Y24Reference(s)Initial TestConcentration(μg/L)Duration(d)Single /Constant /MultipleEcosystemResultsPlantGroupRecoveryCommentsEffect(Y/N)Kosinski, 1984;Kosinski andMerkle, 19841021SingleArtificialstreams,recirculating40% decrease inapparent primaryproductivity; slightdecrease inbiovolume.Peri>21 d (primaryproduction);<7 days(biovolume)Atrazine dissipatedfrom the streamsat a half-life of 3.2days. Effectoccurred at day 7;magnitude of effectfor primaryproductivityestimated usingstudy figures.Results from thetwo publications(Kosinski 1984 andKosinski andMerkle 1984) werecombined becausethey appeared tobe from the sameset of experiments.YKosinski, 1984;Kosinski andMerkle, 1984100021SingleArtificialstreams,recirculating50% decrease inapparent primaryproductivity; 10%reduction inbiovolume.Peri> 21 d(primaryproductivity);14 d(biovolume)Atrazine dissipatedfrom the streamsat a half-life of 3.2days. Effectoccurred at day 7;magnitude of effectfor primaryproductivityestimated usingstudy figures.YKosinski, 1984;Kosinski andMerkle, 19841000021SingleArtificialstreams,recirculating70% decrease inapparent primaryproductivity; 20%to 25% reductionin biovolume.Peri> 21 dAtrazine dissipatedfrom the streamsat a half-life of 3.2days. Effectoccurred at day 7;magnitude of effectfor primaryproductivityestimated usingstudy figures.Y25Reference(s)Initial TestConcentration(μg/L)Duration(d)Single /Constant /MultipleEcosystemResultsPlantGroupRecoveryCommentsEffect(Y/N)Krieger et al., 19882412ConstantArtificialstreams,recirculatingDecrease inbiomass (24%reduction) andchlorophyll-a(30% reduction).Slight decrease(21%, notstatisticallysignificant) innitrate uptake.No effect ondissolved silicauptake orphosphorusuptake rate.PeriNoneEffect observed atlast study day.YKrieger et al., 198813412ConstantArtificialstreams,recirculatingDecrease inbiomass (31%reduction),chlorophyll-a(44% reduction),and nitrate uptake(25%).No effect ondissolved silicauptake; possibleslight effect (8%)on phosphorusuptake rate.PeriNoneEffect observed atlast study day.Y26Reference(s)Initial TestConcentration(μg/L)Duration(d)Single /Constant /MultipleEcosystemResultsPlantGroupRecoveryCommentsEffect(Y/N)Moorhead andKosinski, 1986100007SingleArtificialstreams,recirculatingCommunityproductivity wasdecreased byapproximately 18-fold relative tocontrols andNitzschiaabundance wasreduced byapprox. 60%.Water qualityparameters(conductivity,alkalinity, solublereactivephosphorus, andpH), respiration,and changes innon-Nitzschiaalgal abundancewere not affected.Peri>7 dEffect occurred atday 0 (day ofdosing).YPratt et al., 198833721ConstantMicrocosms,laboratoryflowingStatisticallysignificantdecreases in DO(30%), number ofspecies (15%),chlorophyll-a(90%), proteinbiomass ofprotozoa (40%),potassium (45%),magnesium(20%), andcalcium (15%).Peri> 21 dUnclear whatspecies weretested - wholecommunityendpoints wereevaluated.Colonization anddiversity endpointswere associatedwith protozoa.Effect occurred atday 21.Y27Reference(s)Initial TestConcentration(μg/L)Duration(d)Single /Constant /MultipleEcosystemResultsPlantGroupRecoveryCommentsEffect(Y/N)Stay et al., 1989204 (initialmeasured)42SingleMicrocosms,laboratoryLeffler30% decrease inpH; 80%decrease inprimaryproduction; noeffect on darkrespiration orheterotrophicactivity.Phyto42 - >42 dMagnitude of effectestimated fromgraphs.YStay et al., 198950042SingleMicrocosms,laboratoryLeffler30% decrease inpH; 120%decrease inprimaryproduction; noeffect on darkrespiration orheterotrophicactivity.Phyto> 42 dMagnitude of effectestimated fromgraphs.YStay et al., 1989100042SingleMicrocosms,laboratoryLefflerDecrease in pHand primaryproduction(magnitude notspecified); noeffect on darkrespiration orheterotrophicactivity.Phyto> 42 dMagnitude of effectestimated fromgraphs; values for1000 μg/L werenot presented butwere reported tobe similar to the500 μg/L testconcentration.YStay et al., 1989500042SingleMicrocosms,laboratoryLefflerDecrease in pHand primaryproduction(magnitude notspecified); noeffect on darkrespiration orheterotrophicactivity.Phyto> 42 dMagnitude of effectestimated fromgraphs; values for5000 μg/L werenot presented butwere reported tobe similar to the500 μg/L testconcentration.Y28Reference(s)Initial TestConcentration(μg/L)Duration(d)Single /Constant /MultipleEcosystemResultsPlantGroupRecoveryCommentsEffect(Y/N)Brockway et al.,19845055ConstantMicrocosms,labcontinuousflowApprox. 30%decrease inoxygen productionand 50% increasein dissolvednitrateconcentration.Phyto>55 dExposure was 50μg/L (day 0 to 55)+ 0 μg/L (removalof atrazine fromthe system at day56) + 50 μg/L (day63 to 70); recoverywas associatedwith removal ofatrazine at day 55,and recoveryoccurred relativelyrapidly. Effectoccurred at day 7;exposure levelsare nominal.YBrockway et al.,198410015ConstantMicrocosms,labcontinuousflowApprox. 40%decrease inoxygen productionand approx. 65%increase indissolved nitrateconcentration.Phyto>15 dExposure wascomplex - 100 μg/Lwas tested afterexposure to 0.5μg/L and 50 μg/L.Treatment was asfollows: 0.5 μg/L(days 0 to 28) + 50μg/L (day 29) +100 μg/L (day 35)+ 0 μg/L (removalof atrazine fromthe system at day50) + 100 μg/L(day 63). Effectoccurred on thefirst day oftreatment with 100μg/L.Y29Reference(s)Initial TestConcentration(μg/L)Duration(d)Single /Constant /MultipleEcosystemResultsPlantGroupRecoveryCommentsEffect(Y/N)deNoyelles et al.,1989100360SingleMesocoms,experimentalpondsDecrease (>90%decline) in14Cuptake andbiomass ofphytoplankton.Phyto>21 dEffect observedimmediately (withinfirst 3 wks) in both136-d and 805-dstudies during thefirst year.Recoveryobserved >3weeks.YdeNoyelles et al.,1989200360SingleMesocoms,experimentalpondsDecrease (>90%decline) in14Cuptake andbiomass ofphytoplankton.Phyto>21 dEffect observedimmediately (withinfirst 3 wks) in both136-d and 805-dstudies during thefirst year.Recoveryobserved >3weeks.YKosinski, 1984;Kosinski andMerkle, 198410021SingleArtificialstreams,recirculating30% decrease inapparent primaryproductivity; noaffect onbiovolume.Peri< 3 dEffect occurred atday 0 and recoveryoccurred by day 3.YMoorhead andKosinski,19861007SingleArtificialstreams,recirculatingCommunityproductivity wasdecreased byapproximately 8-fold relative tocontrols.Water qualityparameters(conductivity,alkalinity, solublereactivephosphorus, andpH), respiration,and changes inalgal abundancewere not affected.Peri7 dEffect occurred atday 0.Y30Reference(s)Initial TestConcentration(μg/L)Duration(d)Single /Constant /MultipleEcosystemResultsPlantGroupRecoveryCommentsEffect(Y/N)Moorhead andKosinski, 198610007SingleArtificialstreams,recirculatingCommunityproductivity wasdecreased byapproximately 8-fold relative tocontrols.Water qualityparameters(conductivity,alkalinity, solublereactivephosphorus, andpH), respiration,and changes inalgal abundancewere not affected.Peri>7 dEffect oncommunityproductivityremained at theend of the 7 daystudy. Effectoccurred at day 0.YStay et al., 19855353SingleMicrocosms,laboratoryTaub (picklejars)40% reduction in14C-uptake; 15-20% reduction inDO; 60%reduction in netprimaryproductivity; and~50% reduction in14C-uptake/chl-a.Phyto21 - 32 d; 53 dDaphnid bloomoccurred betweendays 18 and 35 ofthe study andstrongly interactedwith the effects ofthe atrazinetreatments. Onlyatrazine-relatedeffects thatoccurred prior tothe daphnid bloomon day 18 areconsidered. Fullduration of studywas 60 days withatrazine addition atday 7.Y31Reference(s)Initial TestConcentration(μg/L)Duration(d)Single /Constant /MultipleEcosystemResultsPlantGroupRecoveryCommentsEffect(Y/N)Stay et al., 19858453SingleMicrocosms,laboratoryTaub (picklejars)55% reduction in14C-uptake; 20-30% reduction inDO; 55%reduction in netprimaryproductivity; and~55% reduction in14C-uptake/chl-a.Phyto28 - 32 d; 53 dDaphnid bloomoccurred betweendays 18 and 35 ofthe study andstrongly interactedwith the effects ofthe atrazinetreatments. Onlyatrazine-relatedeffects thatoccurred prior tothe daphnid bloomon day 18 areconsidered. Fullduration of studywas 60 days withatrazine addition atday 7.YStay et al., 198517053SingleMicrocosms,laboratoryTaub (picklejars)70% reduction in14C-uptake; 45-55% reduction inDO; 100%reduction in netprimaryproductivity; and~65% reduction in14C-uptake/chl-a.Phyto28 - 32 d; 53 dDaphnid bloomoccurred betweendays 18 and 35 ofthe study andstrongly interactedwith the effects ofthe atrazinetreatments. Onlyatrazine-relatedeffects thatoccurred prior tothe daphnid bloomon day 18 areconsidered. Fullduration of studywas 60 days withatrazine addition atday 7.Y32Reference(s)Initial TestConcentration(μg/L)Duration(d)Single /Constant /MultipleEcosystemResultsPlantGroupRecoveryCommentsEffect(Y/N)Stay et al., 198910042SingleMicrocosms,laboratoryLefflerDecrease in pH(20%) andprimaryproduction (50%).Dark respirationand heterotrophicactivity were notaffected bytreatment.Phyto7 - >42 dRecovery did notappear to occur forthe primaryproductionendpoint. Effectoccurred at day 0;magnitude of effectwas estimatedfrom study figures.YBrockway et al.,19845012SingleMicrocosms,lab stagnantApprox. 25%reduction inoxygenproduction.Phyto> 12 dEffect occurred atday 1.YdeNoyelles et al.,1982; deNoyelleset al., 19892063SingleMesocoms,experimentalpondsDecrease (50%decline) in14Cuptake andbiomass ofphytoplankton.Phyto>3 wks forbiomass and14C-uptakeAlthough fullexposure periodwas 136-d,atrazine exposureconcentrations areavailable for only63 days.YJohnson,19861030SingleMicrocosm,lab stagnantNo effect onmacrophytebiomass,conductivity, pH,or alkalinity.Slight (20%)decrease in grossprimaryproductivity at thefirstmeasurement.However, thisobservation didnot appear to berelated to atrazinetreatment.Macro7 dExposure levelswere notmeasured andatrazine wasintroduced as aformulated productassociated withsoil. Primaryproductivity waslower than controlsfrom day 2 to 7.N33Reference(s)Initial TestConcentration(μg/L)Duration(d)Single /Constant /MultipleEcosystemResultsPlantGroupRecoveryCommentsEffect(Y/N)Johnson, 198610030SingleMicrocosm,lab stagnantNo effect onmacrophytebiomass,conductivity, pH,or alkalinity.Slight (30%)decrease in grossprimaryproductivity.However, thisobservation didnot appear to berelated to atrazinetreatment.Macro7 dExposure levelswere notmeasured andatrazine wasintroduced as aformulated productassociated withsoil. Primaryproductivity waslower than controlsfrom day 2 to 7.NLampert et al.,1989118SingleLakeenclosure50% decrease inchlorophyll-a andoxygen saturation.Phyto>18 dReductions inoxygen may havebeen related todaphnid mortality.However,chlorophyll-areductions wereconsidered to betreatment related.YLampert et al.,19890.121 to 42SingleLakeenclosureDecrease inphotosynthesisrate (1 of 2replicates incoldwaterexperiment only,60% decline) andoxygen saturation(approx. 40%reduction).No clear effect onchlorophyll-alevels.Phyto>42 d(oxygen)>25 d(photosynthetic rate)Endpointsevaluated includechlorophyll-alevels, oxygenlevels, andphotosyntheticrate. Recoverywas observed forthe photosyntheticrate in someenclosures.Y34Reference(s)Initial TestConcentration(μg/L)Duration(d)Single /Constant /MultipleEcosystemResultsPlantGroupRecoveryCommentsEffect(Y/N)Pratt et al., 198832 (meanmeasured)21ConstantMicrocosms,laboratoryflowing35% decrease inDO (statisticallysignificant); slightreductions inmagnesium andcalcium levels.No effect onnumber ofspecies,chlorophyll-a,protein biomass ofprotozoa, orpotassium.Peri> 21 d--YPratt et al., 1988110 (meanmeasured)21ConstantMicrocosms,laboratoryflowing35% decrease inDO; 60%reduction inchlorophyll-a (notstatisticallysignificant); slightreductions inmagnesium andcalcium levels.No effect onpotassium,number ofspecies, or proteinbiomass ofprotozoa.Peri> 21 d--YStay et al., 19892042SingleMicrocosms,laboratoryLefflerSlight (10%)decrease inprimaryproduction.No effect on pH,respiration, orheterotrophicactivity.Phyto1-10 d--N35Reference(s)Initial TestConcentration(μg/L)Duration(d)Single /Constant /MultipleEcosystemResultsPlantGroupRecoveryCommentsEffect(Y/N)van den Brink etal., 1995535ConstantMicrocosms,laboratorySlight decrease inphotosyntheticactivity, asindicated byhigherconductivity andalkalinity, andlower DO and pH.PhytoNot applicable--NBrockway et al.,19840.57SingleMicrocosms,lab stagnantNo effect onoxygenproduction.PhytoNot applicable--NBrockway et al.,198457SingleMicrocosms,lab stagnantNo effect onoxygenproduction.PhytoNot applicable--NBrockway et al.,19840.529ConstantMicrocosms,labcontinuousflowNo effect onoxygenproduction.PhytoNot applicable0.5 μg/L exposureoccurred for 29days, thenexposure wasincreased to 50μg/L; exposurelevels are nominal.NBrockway et al.,1984570ConstantMicrocosms,labcontinuousflowOxygenproduction wasslightly reducedfrom days 10 to45. Oxygenproduction wastypically within90% of controls,but wasapproximately80% of controlsfor about 7 daysduring the firstmonth of thestudy.PhytoApprox. 45 d--N36Reference(s)Initial TestConcentration(μg/L)Duration(d)Single /Constant /MultipleEcosystemResultsPlantGroupRecoveryCommentsEffect(Y/N)Gruessner andWatzin, 1996514Single withdecreasingconc.Microcosm,labNo effect on chl-aof periphyton onartificial substrate.PeriNot applicableConcentration ofatrazine reducedto 1μg/L by day 14;on day 3, 15% ofthe treated waterwas removed andreplaced withuntreated streamwater. On days 6and 7 about 50%of the water wasreplaced; 15% ofthe water wasreplaced again onday 11.NGustavson andWängberg, 1995120SingleLakeenclosureNo effect oncommunitytolerance.PhytoandPeriNot applicable--NGustavson andWängberg,19952020SingleLakeenclosureNo effect oncommunitytolerance.PhytoandPeriNot applicable--NGustavson andWängberg, 19951020SingleLakeenclosureNo effect oncommunitytolerance.PhytoandPeriNot applicable--NJurgensen andHoagland, 19902282 shortpulses of24-hours@ day 1and 14StreamenclosuresNo effect on celldensity orbiomass.PeriNot applicableStudy results mayhave beenconfounded by astorm event and bythe high detectionlimit of theanalytical methodsused in this study(50 μg/L).N37Reference(s)Initial TestConcentration(μg/L)Duration(d)Single /Constant /MultipleEcosystemResultsPlantGroupRecoveryCommentsEffect(Y/N)Jurgensen andHoagland, 199030282 shortpulses of24-hours@ day 1and 14StreamenclosuresNo effect on celldensity orbiomass.PeriNot applicableStudy results mayhave beenconfounded by astorm event and bythe high detectionlimit of theanalytical methodsused in this study(50 μg/L).NJurgensen andHoagland, 1990100282 shortpulses of24-hours@ day 1and 14StreamenclosuresNo effect on celldensity orbiomass.PeriNot applicableStudy results mayhave beenconfounded by astorm event and bythe high detectionlimit of theanalytical methodsused in this study(50 μg/L).NLynch et al., 19852530 (4 30-dexposureswith 60-dintervalsb/wexposures)Constant/Multiple(seecomment)Artificialstreams,laboratoryNo effect onstanding biomass,rate of primaryproduction, orcommunityrespiration.PeriNot applicableDMSO was usedas a solvent, andpossible solventeffects were noted.Atrazineconcentrationswere notanalyticallyconfirmed.Streams weretreated in four 30-day phases with60 day recoverytime between each30 day exposure.N38Reference(s)Initial TestConcentration(μg/L)Duration(d)Single /Constant /MultipleEcosystemResultsPlantGroupRecoveryCommentsEffect(Y/N)Pratt et al., 19883.2 (meanmeasured)21ConstantMicrocosms,laboratoryflowingNo effect on DO,chlorophyll-a,protein biomass ofprotozoa, numberof species,magnesium,calcium, orpotassium.PeriNot applicable--NPratt et al., 198810 (meanmeasured)21ConstantMicrocosms,laboratoryflowingNo effect on DO,chlorophyll-a,protein biomass ofprotozoa, numberof species,magnesium,calcium, orpotassium.PeriNot applicable--NRohr andCrumrine, 20052530MultipleMesocosms,experimentalpondsReduction inperiphytonchlorophyll-a(15.2%).PeriRecovery notreportedInitial dose ofatrazine was 25μg/L, (nominal)then after twoweeks the pondswere redosed with25 μg/L (nominal).Thus the exposurefor the first twoweeks was 25 μg/L(nominal) and theauthors assumedthe exposure forthe second twoweeks was 50 μg/L(nominal).Y39Reference(s)Initial TestConcentration(μg/L)Duration(d)Single /Constant /MultipleEcosystemResultsPlantGroupRecoveryCommentsEffect(Y/N)Rohr et al., 200811728SingleMesocosms,experimentalpondsReduction inphytoplanktonchlorophyll-a(65%) andincrease inperiphytonchlorophyll-a(49%).PeriandPhytoRecovery notreportedChlorophyll wasmeasured only atstudy termination.Study authorsattribute increasein periphytonchlorophyll-a toreduction inphytoplankton,which facilitatesincreased nutrientavailability andlight penetration toperiphyton.YRelyea, 20096.436SingleOutdoormesocosms,experimentalpondsNo effect tophytoplanktonchlorophyll-a,periphytonbiomass, anddissolved oxygen.PeriandPhytoNot applicableSolventconcentrationreported for controlonly.N40Reference(s)Initial TestConcentration(μg/L)Duration(d)Single /Constant /MultipleEcosystemResultsPlantGroupRecoveryCommentsEffect(Y/N)Knauert et al.,2008; Knauert etal., 200984173MultipleOutdoormesocosms,experimentalpondsInhibition ofphytoplanktonphotosyntheticactivity (51.4%) atday 2. Averageinhibition ofphotosyntheticactivity from day0-34 was 45.6%.Change inphytoplanktoncommunitystructure.PhytoNo recovery(compared tocontrol ponds,atrazineresulted instatisticallysignificanteffects onphotosynthesis anddifferences inphytoplanktonspeciescompositionuntil the end oftheexperiment atday 173).Study durationincluded 34 daysof constantatrazine exposurefollowed by a postexposure period ofapproximately 5months (139 days)where atrazinedissipated in thewater column. Thetotal duration ofthe study was 173days. In order tomaintain constantatrazineconcentrations,atrazine wasreapplied to theponds only onceon day 20.Atrazine caused astatisticallysignificantreduction inphotosyntheticactivity ofphytoplankton atday 2 of the study.Changes inphytoplanktoncommunitystructure began atday 12.Y41Reference(s)Initial TestConcentration(μg/L)Duration(d)Single /Constant /MultipleEcosystemResultsPlantGroupRecoveryCommentsEffect(Y/N)Berard et al.,1999a, Berard etal., 1999b, Berardand Benninghoff,2001, Sequin etal., 2001b,Leboulanger et al.,20011010 to 23SingleExperimentaloutdoormicrocosmsChange inphytoplanktonbiomass andcommunitystructure (speciesand highertaxonomicgroupingscomposition,species diversity(Shannon index),and Bray-Curtisindex).PhytoRecovery notreportedReported atrazineconcentration insource lake isrelatively lowcompared totreatmentconcentration,althoughbackgroundmeasurementswere not takenduring theexperiment andmay have beenhigher. Studyauthors indicatethat experimentswere conducted for10-23 days (justbefore thestationary phase ofphytoplanktongrowth).Endpoints weremeasured at theend of theexperiments; thetype andmagnitude ofeffects variedamong theexperiments andeffects wereobserved acrossthe range ofexperimentaldurations.Y42Reference(s)Initial TestConcentration(μg/L)Duration(d)Single /Constant /MultipleEcosystemResultsPlantGroupRecoveryCommentsEffect(Y/N)Seguin et al.,2001a3040SingleOutdoormesocosms,experimentalpondsIncrease (61%) inperiphytonchlorophyll-aconcentration atDay 40.PeriRecovery notreportedIncreasedchlorophyllobserved only atstudy termination.Also examinedeffects ofnicosulfuran inseparatetreatments.NSeguin et al.,2001a240SingleOutdoormesocosms,experimentalpondsNo effectPeriNot applicableNon-significantincrease (14%) inperiphytonchlorophyll-aconcentration atday 40. Alsoexamined effectsof nicosulfuran inseparatetreatments.NSeguin et al.,2001b3040SingleExperimentaloutdoormesocosmsChange inphytoplanktoncommunitystructure (changein Bray-Curtisindex starting onday 2 andincreasedChrysophyceaeabundance ofunknownmagnitude on day40).PhytoRecovery notreportedAlso examinedeffects ofnicosulfuran inseparatetreatments.YSeguin et al.,2001b240SingleExperimentaloutdoormesocosmsIncreasedChrysophyceaeabundance onday 40 (unknownmagnitude).PhytoRecovery notreportedEffect onabundanceobserved at studytermination. Alsoexamined effectsof nicosulfuran inseparatetreatments.Y43Reference(s)Initial TestConcentration(μg/L)Duration(d)Single /Constant /MultipleEcosystemResultsPlantGroupRecoveryCommentsEffect(Y/N)Seguin et al., 20023025SingleExperimentaloutdoormesocosmsDecrease inchlorophyll-a(22%) and dryweight (30%);change incommunitystructure andBray-Curtissimilarity index;decrease in DO(20%).PhytoNoChanges inbiomass(chlorophyll-aanddry weight) wereevident at day 9,changes incommunitystructure began atday 11, changes inBray-Curtis beganday 9, andchanges in DOabout day 3.Although DOshowed anapparent recoveryabout day 12, itdiverged from thecontrol againstarting about day17 through the endof the experiment.Short-term toxicitydata from theatrazine-treatedmesocosmcommunities wasnot considered forthe data summarytable due to theuncertaintysurroundingexposureconcentrations.Y44Reference(s)Initial TestConcentration(μg/L)Duration(d)Single /Constant /MultipleEcosystemResultsPlantGroupRecoveryCommentsEffect(Y/N)Downing et al.,20041487SingleLaboratorymicrocosmsDecrease inchlorophyll-a(30-40%), primaryproductivity(~60%), andchange inphytoplanktoncomposition(~20% decreasein diatoms, ~25%decrease inbluegreen algae,~30% decrease ingreen algae,~75% decrease inbrown algae,~30% decrease intotalphytoplankton).PhytoRecovery notreportedInitial testconcentrations arebased on theaverage ofreported measuredday 0 values fromthe October 1999and February 2000experiments (112 -184 μg/L); thecorrespondingnominal testconcentration is200 μg/L.Chlorothalnil andendosulfan werealso investigatedseparately.YDowning et al.,200424.37SingleLaboratorymicrocosmsDecrease inchlorophyll-a(~35%) andchange inphytoplanktoncomposition(~15% decreasein diatoms, ~5%decrease in greenalgae, ~25%decrease in brownalgae, ~10%decrease in totalphytoplankton).PhytoRecovery notreportedInitial testconcentrations arebased on theaverage ofreported measuredday 0 values fromthe October 1999and February 2000experiments (23.8- 24.8 μg/L) ); thecorrespondingnominalconcentration is 20μg/L. Chlorothalniland endosulfanwere alsoinvestigatedseparately.Y45Reference(s)Initial TestConcentration(μg/L)Duration(d)Single /Constant /MultipleEcosystemResultsPlantGroupRecoveryCommentsEffect(Y/N)Boone and James,200320725SingleOutdoormesocosms,experimentalpondsNo cleartreatment-relatedeffects.PhytoNot applicableMain purpose ofthe study was toevaluate effects ofatrazine andcarbaryl onamphibians.Chlorophyllcontent wasmeasured as apotential indirecteffect (effect onfood availability) toamphibians.Control levels werehigher than alltreatment levels(regardless ofwhether or notatrazine waspresent) at day 12in Experiment 1.However, therewere no apparentdecreases inchlorophyll in anytreatment withatrazine andchlorophyll in theatrazine-onlytreatment washigher than thecontrol on day 25.N46Reference(s)Initial TestConcentration(μg/L)Duration(d)Single /Constant /MultipleEcosystemResultsPlantGroupRecoveryCommentsEffect(Y/N)Diana et al., 20002051SingleOutdoormicrocosmsNo cleartreatment-relatedeffects.MacroandPhytoNot applicableAtrazineconcentrationswere onlydetermined at 0and 21 days posttreatment.Chlorophyll wasmeasured throughday 42 andmacrophytesbiomass wasmeasured at theend of theexperiment (day51).NDiana et al., 200019651SingleOutdoormicrocosms98% decrease inmacrophytebiomass; 3-foldincrease inphytoplanktonchlorophyll-a onday 14;approximate 60%reduction in predusk DO levels atday 1.MacroandPhytoNo –chlorophyll-aincrease wasobserved fromday 14 tostudytermination;DO did notrecover, andbiomass wasonly measuredat studytermination.Atrazineconcentrationswere onlydetermined at 0and 21 days posttreatment.Chlorophyll wasmeasured throughday 42 andmacrophytesbiomass wasmeasured at theend of theexperiment (day51).Y47Reference(s)Initial TestConcentration(μg/L)Duration(d)Single /Constant /MultipleEcosystemResultsPlantGroupRecoveryCommentsEffect(Y/N)Diana et al., 2000203651SingleOutdoormicrocosms99% decrease inmacrophytebiomass; 2-foldincrease inphytoplanktonchlorophyll-a;approximate 80%reduction in predusk DO levels atday 1.MacroandPhytoNo - biomasswas onlymeasured atstudytermination,and DO levelsdid notrecover.However,chlorophyllconcentrationswere similar tocontrol by day42.Atrazineconcentrationswere onlydetermined at 0and 21 days posttreatment.Chlorophyll wasmeasured throughday 42 andmacrophytesbiomass wasmeasured at theend of theexperiment (day51).YMcGregor et al.,20082542SingleOutdoormicrocosmsNo effect ondissolved oxygen.MacroandPhytoNot applicableDO was measuredthrough day 40.Study focused onmacrophytes,however DOmeasurementswould haveincluded effects onphytoplanktonpresent in themicrocosms.Effects onmacrophytebiomass were alsoreported in thestudy; however, noeffect levels werereported forbiomass effects.N48Reference(s)Initial TestConcentration(μg/L)Duration(d)Single /Constant /MultipleEcosystemResultsPlantGroupRecoveryCommentsEffect(Y/N)McGregor et al.,20085042SingleOutdoormicrocosmsNo effect ondissolved oxygen.MacroandPhytoNot applicableDO was measuredthrough day 40.Study focused onmacrophytes,however DOmeasurementswould haveincluded effects onphytoplanktonpresent in themicrocosms.Effects onmacrophytebiomass were alsoreported in thestudy; however, noeffect levels werereported forbiomass effects.NMcGregor et al.,200810042SingleOutdoormicrocosms35% decrease inDO at day 1.MacroandPhytoNoDO was measuredthrough day 40.Study focused onmacrophytes,however DOmeasurementswould haveincluded effects onphytoplanktonpresent in themicrocosms.Effects onmacrophytebiomass were alsoreported in thestudy; however, noeffect levels werereported forbiomass effects.Y49Reference(s)Initial TestConcentration(μg/L)Duration(d)Single /Constant /MultipleEcosystemResultsPlantGroupRecoveryCommentsEffect(Y/N)McGregor et al.,200825042SingleOutdoormicrocosms50% decrease inDO at day 1.MacroandPhytoNoDO was measuredthrough day 40.Study focused onmacrophytes,however DOmeasurementswould haveincluded effects onphytoplanktonpresent in themicrocosms.Effects onmacrophytebiomass were alsoreported in thestudy; however, noeffect levels werereported forbiomass effects.Y