Table 5.
Summary of the effects of atrazine on general gonadal morphology.
| Taxon, species | End point | Effect direction | Conc where effect was observed (μg/L) | Conc tested (μg/L) | Atrazine grade | Experiment type | Exposure duration | Reference |
|---|---|---|---|---|---|---|---|---|
| Testes | ||||||||
| Fish | ||||||||
| Pimephales promelas | Testis size corrected for body size | ND | 5, 50 | 5, 50 | Tech | SR | 21 days | Bringolf et al. 2004a |
| P. promelas | Spermatogenic tubule diameter | ↓ | 250 | 25, 250 | Tech | FT | 21 days | U.S. EPA 2005 |
| Frog | ||||||||
| X. laevis | Discontinuous gonads (abnormal segmentation) | ↑ | 25 | 1.0, 10, 25 | Tech | SR | ~78 days during larval period | Carr et al. 2003 |
| X. laevis | Ambiguous gonads (not obviously male or female) | ↑ | 25 | 1.0, 10, 25 | Tech | SR | ~78 days during larval period | Carr et al. 2003b |
| X. laevis | Testis size corrected for body size | ↑ | 10 | 10, 100 | Tech | SR | 48 days | Hecker et al. 2005aa |
| X. laevis | Sperm/area | ND | – | 10, 100 | Tech | SR | 48 days | Hecker et al. 2005aa |
| X. laevis | Testis size corrected for body size | ND | – | 1, 25, 250 | Tech | SR | 36 days | Hecker et al. 2005aa |
| R. clamitans | Testis size corrected for body size | ↓ in juvenile males | ND–3.13 | ND–3.13c | Comm | FS | Unknown | McDaniel et al. 2008c |
| R. pipiens | TOFs (testicular oocytes) | ↑ where atrazine was detected in 2003c | ND–3.14 | ND–3.13c | Comm | FS | Unknown | McDaniel et al. 2008c,d |
| Various spp., mostly R. clamitans | Discontinuous testes (abnormal segmentation) | ND | – | ND–2e | Comm | FS | Unknown | Murphy et al. 2006a |
| Various spp., mostly R. clamitans | Intersex (having testicular and ovarian tissues) | ND | – | ND–2e | Comm | FS | Unknown | Murphy et al. 2006a |
| Various spp., mostly R. clamitans | TOFs (testicular oocytes) | ↑ in 1 of 2 years in juveniles, positively correlated with max atrazine Conc in that year | ND–0.73 | ND–2e | Comm | FS | Unknown | Murphy et al. 2006a |
| R. clamitans | Testis size corrected for body size | ↑ in adult males at agricultural sites in 1 of 2 years | ND–250 | ND–2e | Comm | FS | Unknown | Murphy et al. 2006bf |
| X. laevis | Hermaphroditism (testicular oocytes, intersex, mixed sex) | ND | – | 0.1, 1, 10, 100 | Tech | SR | ~ 65 days during larval period | Oka et al. 2008 |
| Acris crepitans | Intersex or testicular oocytes | Trend for ↑ p = 0.07 | Atrazine detections | ND–70 | Comm | FS | Unknown | Reeder et al. 1998g |
| Ovaries | ||||||||
| Fish | ||||||||
| P. promelas | Ovary size corrected for body size | Trend for ↓ | 50 | 5, 50 | Tech | SR | 21 days | Bringolf et al. 2004a |
| P. promelas | Proportion of oocytes undergoing atresia | ND | – | 25, 250 | Tech | FT | 21 days | U.S. EPA 2005 |
| Frog | ||||||||
| H. versicolor, R. sphenocephala | Ovarian developmental stage | ND | – | 1, 3, 30h | Tech | SR | Through metamorphosis | Storrs and Semlitsch 2008 |
| B. americanus | Ovarian developmental rate | ND | – | 1, 3, 30h | Tech | SR | Through metamorphosis | Storrs and Semlitsch 2008 |
Abbreviations: ↓, decreased; ↑, increased; Comm, commercial; Conc, concentration; FS, field survey; FT, flow-through experiment; ND, not detected; SR, static renewal experiment, Tech, technical. Excluded studies are listed in Supplemental Material, Table S1 (doi:10.1289/ehp.0901164.S1).
No test statistics or degrees of freedom are presented; however, means and variances were presented either in the text or in a figure of the article.
Xenopus are typically sexually differentiated at the gross morphologic level at metamorphosis; individuals in this study exposed to 25 μg/L were so sexually ambiguous they were initially considered intersex (having both testicular and ovarian issues).
Atrazine concentration for the nonagricultural reference site during 2003 was reported incorrectly; repeated attempts to contact the authors for clarification have not been forthcoming.
When atrazine concentrations were highest (2003), TOFs per individual occurred in higher numbers; TOFs were positively associated with atrazine, nitrate, and quantity of pesticides in a multivariate comparison, suggesting that atrazine is contributing to TOFs.
Concentrations were between ND and 2 except on two occasions at one site, when levels were 65 and 250 μg/L.
Authors argued that differences in GSI between agricultural and nonagricultural sites cannot be due to atrazine because GSI does not correlate with atrazine concentration; however, they presented no statistics to support this claim.
The relationship between detection of atrazine and the presence of one or more intersex cricket frogs approached significance (p = 0.07).
The actual concentration of the 30-μg/L treatment was 125 μg/L.