Table 1.

Summary of the results for the effects of atrazine on the developmental rate and size at or near metamorphosis for amphibians.

	Net effect on developmental rate				Size at or near metamorphosis
Taxon, species	Effect direction	Conc where effect was observed (μg/L)	Nonmono-tonic dose response	Excluded from meta-analysis?	Effect direction	Conc where effect was observed (μg/L)	Nonmono-tonic dose response	Excluded from meta-analysis?	Conc tested (μg/L)	Atrazine grade	Experiment type	Exposure duration	Reference
Frog
Bufo americanus	ND	–	NA	No	↓	200	NA	No	200	Comm; Aatrexa	PE	≤ 88 days	Boone and James 2003b
B. americanus	↓c	250, 500, 1,000	Yes	No	↓d	No Conc differed from controls	No	No	250, 500, 1,000, 5,000, 10,000	Tech	SR	3 weeks	Freeman et al. 2005
B. americanus	ND	–	No	No	No data	–	No data	Yes	1, 3, 30	Tech	SR	LTM	Storrs and Semlitsch 2008
Rhinella arenarum	↑ at 100 and 1,000, ↓ at 5,000	100, 1,000, 5,000	Yes	No	No data	–	No data	Yes	100, 1,000, 5,000	Tech	SR	LTM	Brodeur et al. 2009
Hyla chrysoscelis	↑	192	No	No	No data	–	No data	Yes	96, 192	Tech	PE, two pulses	≤ 129 days	Briston and Threlkeld 1998b
Hyla versicolor	NDe	–	Possibly	No	↓	200, 2,000	No	No	20, 200, 2,000	Tech	PE	Mean of 13 days	Diana et al. 2000f
H. versicolor	ND	–	NA	No	No data	–	No data	Yes	1, 3, 30	Tech	SR	LTM	Storrs and Semlitsch 2008
Rana clamitans	↓	10	Yes	No	↓	10	Yes	No	10, 25	Tech	SR	≤ 273 days	Coady et al. 2004f
Rana pipiens	Unknowng	–	No	Yes	↓h	Not tested	No	No	20, 200	Tech	SR	LTM	Allran and Karasov 2000
R. pipiens	ND	–	NA	No	↓	0.1	NA	No	0.1	Tech	SR	LTM	Hayes et al. 2006
R. pipiens	ND	–	NA	No	ND	–	NA	No	5	Not provided	SR	ETM, ≤ 45 days	Bridges et al. 2004i
Rana sphenocephala	ND	–	NA	No	↓	200	NA	No	200	Comm; Aatrexa	PE	≤ 57 days	Boone and James 2003b
R. sphenocephala	ND	–	NA	No	No data	–	No data	Yes	1, 3, 30	Tech	SR	LTM	Storrs and Semlitsch 2008
Rana sylvatica	No data	–	No data	Yes	↓	Unknown; conc in ponds not provided	NA	No	3, 30	Comm	FS	Unknown	Kiesecker 2002j
Xenopus laevis	No data	–	No data	Yes	ND	–	No	No	1, 10, 25	Tech	SR	Mean of 56 days	Carr et al. 2003
X. laevis	ND	–	NA	No	No data	–	No data	Yes	1, 10, 25	Tech	SR	ETM	Du Preez et al. 2008
X. laevis	↑	100, 450, 800	No	No	Unknownk	–	Unknown	Yes	100, 450, 800	Tech	SR	4 weeks	Freeman and Rayburn 2005
X. laevis	Unknown l,m,n	–	Unkown	Yes	↓o	0.01, 1, 100	Possibly	No	0.01, 0.1, 1.0, 25, and 100	Tech	SR	≤ 75 days	Kloas et al. 2009
X. laevis	↓ detected by regression	No Conc differed from controls	No	No	↓	20, 40, 80, 160, 320	No	No	20, 40, 80, 160, 320	Tech	SR	LTM	Sullivan and Spence 2003
X. laevis	No data	–	NA	Yes	↓	400	NA	No	400	Tech	SR	LTM	Langerveld et al. 2009
Salamander
Ambystoma barbouri	↑	40, 400	No	No	↓	400	No	No	4, 40, 400	Tech	SR	Mean of 52 days exposure	Rohr et al. 2004
Ambystoma macrodactylum	↑	184	No	No	↓	184	No	No	1.84, 18.4, 184	Tech	SR	30 days	Forson and Storfer 2006a
Ambystoma tigrinum	↑	16 vs. 1.6, but not vs. 0	Possibly; no data	No	ND; trend toward ↓p	–	No data	No	1.6, 16, 160	Tech	SR	LTM	Forson and Storfer 2006b
Ambystoma maculatum	↑ and ↓q	250	Yes	No	↓	250	No	No	75, 250	Tech	SR	86 days	Larson et al. 1998
A. maculatum	↓	200	NA	No	↓	200	NA	No	200	Comm; Aatrexa	PE	≤ 57 days	Boone and James 2003e
Ambystoma texanum	↓	200	NA	No	↓	200	NA	No	200	Comm; Aatrexa	PE	≤ 88 days	Boone and James 2003b,r

Abbreviations: ↓, decreased; ↑, increased; Comm, commercial; Conc, concentration; ETM, embryo to metamorphosis, or earlier (cases where amphibians metamorphosed before atrazine exposure ceased); FS, field survey; LTM, early larvae to metamorphosis; NA, not applicable (used when there were too few concentrations to evaluate nonmonotonicity); ND, not detected; PE, pulse experiment; SR, static renewal experiment; Tech, technical. Excluded studies are listed in Supplemental Material, Table S1 (doi:10.1289/ehp.0901164.S1).

^aAatrex is 59.2% inactive ingredients.

^bCommunity-level study.

^cAuthors show that atrazine modifies the thyroid axis for both X. laevis and B. americanus.

^dAll five atrazine concentrations tested reduced frog size relative to controls, but no within-group variance estimates were provided.

^e200 ppb developed faster than 2,000 ppb.

^fOnly a single egg mass; might not reflect general response.

^gUse only 50% of the metamorphs in the time to metamorphosis analysis without describing how they selected this subset of metamorphs or why they used only 50% for time to metamorphosis but 100% of the metamorphs for size at metamorphosis.

^hAuthors report an interaction between atrazine and time for frog length, indicating that control animals were larger than those exposed to atrazine by the end of the experiment.

ⁱTested as a mixture of 5 μ/L atrazine and 5 μ/L carbaryl.

^jCompared ponds with and without atrazine; effects might be due to other factors.

^kFrogs lose weight at metamorphosis, thus mass measurements were confounded by grouping tadpole and metamorph weights.

^lProvide no within-group variance estimate.

^mNo statistics provided but conclude that there was no effect of atrazine.

ⁿGraphs for developmental rate through time are indiscernible.

^oDetected effects in only one of two experiments and for females only.

^pp = 0.080 for regression analysis, one-tailed test.

^qResults depended on developmental stage; authors showed that atrazine modifies thyroxine and corticosterone hormones.

^rResults depended on drying conditions.