Implications of atrazine concentrations in drinking water from Ijebu-North, Southwest Nigeria on the hypothalamic-pituitary-adrenal axis

Abstract There is an increasing overdependence and use of atrazine herbicide for the control of pre-and post-emergence broad leaf weeds on maize farms in rural agricultural communities in Nigeria. We carried out a survey of atrazine residue in 69 hand-dug wells (HDW), 40 boreholes (BH) and 4 streams from all the 6 communities (Awa, Mamu, Ijebu-Igbo, Ago-Iwoye, Oru and Ilaporu) in Ijebu North Local Government Area, Southwest Nigeria. The effect of the highest concentration of atrazine detected in the water from each of the communities on the hypothalamic-pituitary-adrenal (HPA) axis of albino rats was investigated. Varying concentrations of atrazine were detected in the HDW, BH and stream waters sampled. The highest concentration of atrazine recorded in the water from the communities ranged from 0.01 to 0.08 mg/L. Although there were no significant differences (p > 0.05) in serum levels of corticosterone, aldosterone and ROS of rats exposed to 0.01, 0.03 and 0.04 mg/L concentrations of atrazine compared to control, a significant increase (p < 0.05) was observed at 0.08 mg/L. Catalase activity increased significantly (p < 0.05) only at 0.03 and 0.04 mg/L of atrazine exposure. Butyrylcholinesterase activity, lipid peroxidation and serum ACTH of rats exposed to all the atrazine concentrations were not significantly different (p > 0.05) compared to control. Atrazine at environmentally relevant concentrations of 0.01, 0.03 and 0.04 mg/L detected in the water may not affect the HPA axis, attention should be given to 0.08 mg/L, which increases the serum corticosterone and aldosterone of the exposed rats.


Atrazine
(2-chloro-4-ethylamino-6-isopropylamino-1,3,5-triazine) is a selective and organochlorine triazine herbicide widely used for the control of pre-and post-emergence broadleaf weeds in crops such as sugarcane, maize, sorghum and wheat (Worthing, 1991).Atrazine has a high potential to contaminate ground and surface water via runoff due to its low adsorption in soils and moderate solubility in water (Schwab et al. 2006).The herbicide has the ability to persist in soils as well as surface and groundwater (Bethsass and Colangelo 2006).
Nigeria is a country with a great agricultural motive and maize is one of the major crops largely produced (Adeite 2021).Maize and its products are the second grown crop after cassava in Nigeria and are consumed across vast age groups from infants to the aged.To ensure the continuous high maize production in Nigeria, farmers under the egis of the Maize Growers and Processing Association of Nigeria resorted to the use of different formulations of atrazine including Gasaprim and Atraforce for weeds control instead of manual labor.The increasing use of atrazine in Nigeria is now a major concern of national interest due to its reported contamination of groundwater, which may increase the risk of exposure for children and adults (US EPA 2007).
Groundwater has been reported to account for up to 20% of water supply worldwide and is the major source of drinking water in some countries (Chen et al. 2017), especially in rural areas (Gao et al. 2020).However, groundwater pollution through natural or anthropogenic activities could pose fundamental health risks to individuals (Qian et al. 2020).In support of this, infants and children were reported to be at risk of fluoride and nitrate contamination in groundwater in the Zhongning area, Northwest China, where rural inhabitants mainly depend on groundwater for drinking (Chen et al. 2017).Natural and anthropogenic factors including carbonate weathering and evaporate dissolution and evaporation were reported as the major factors regulating the distribution of a contaminant in groundwater (Chen et al. 2021).It was then suggested that the assessment of natural background levels (NBLs) of contaminants on a regional scale may provide the basis for identifying groundwater pollution and help in the management and effective protection of groundwater resources (Gao et al. 2019(Gao et al. , 2020)).
Over the years, the USEPA and other regulatory agents were mandated via the Food Quality Protection Act of 1996 (FQPA) to evaluate the health risk associated with exposure to atrazine through drinking water.Following a series of groundwater surveys of atrazine carried out in rural agricultural areas by some regulatory bodies in Canada and the USA (Ontario Ministry of the Environment 1987, US EPA 1989, Ritter 1990, Quackenboss et al. 2000, Focazio 2006, MDH 2009), the USDA Pesticide Data Program monitoring for pesticide residues in foods and water later prompted the USEPA and Canada to establish a maximum permissible limit of 3 mg/L (US EPA 2003) and 5 mg/L (Health Canada 1993) for atrazine in water respectively.However, a similar survey of atrazine has not been carried out in some rural agricultural communities in Nigeria and establish a maximum permissible limit for atrazine in drinking water.
Meanwhile, Abarikwu et al. (2010) studied specific effects of atrazine exposure in rats exposed to atrazine at 0, 100, and 200 mg/kg body weight for 7 and 16 days.The herbicide was observed to elicit a depletion of the antioxidant defence system in the testis and epididymis, indicating the induction of oxidative stress, an imbalance between productions of reactive oxygen species (ROS) and antioxidant defence that was implicated in the molecular mechanisms of atrazine toxicity in animals (Abarikwu et al. 2010).Other authors who have evaluated the stress responses of animals to atrazine solely based their study on oxidative stress in some organs of the body including the liver (Gojmerac et al. 1995, Adesiyan et al. 2011, Singh et al. 2011, Campos-Pereira et al. 2012, Abarikwu 2014), kidney (Jestadi et al. 2014, Liu et al. 2014), testes (Stoker et al. 2000, Zirkin et al. 2001, Hayes 2004, Swan 2006, Saalfeld et al. 2018), and brain (Rodriguez et al. 2005, Coban andFilipov 2007).In addition, prolonged exposure to atrazine has been reported to suppress immune cell functions by inducing spleen cell apoptosis in rats (Ge et al. 2021).Xing et al. (2012) reported a concentrationdependent decrease in the activities of antioxidant enzymes in the brain and kidney of common carp following atrazine exposure.
In order to understand the stress response of an animal to atrazine, it is important to study its impact on the hypothalamic-pituitary-adrenal (HPA) hormones known to be involved in stress mediation in animals (Neil, 2004Jessica et al. 2006, Johnson and Grippo 2006).Meanwhile, there are demonstrations that atrazine exposure at 25 to 200 mg/kg rapidly activates the HPA axis, thereby increasing the plasma levels of corticosterone, adrenal-derived progesterone and adrenocorticotropic hormone (ACTH) in animals (Fraites et al. 2009, Laws et al. 2009, Foradori et al. 2018).Hence, a study on the response of endogenic stress hormones and antioxidant defence parameters to the physiological effect as a result of exposure to atrazine is required, mostly in the body circulating fluid of the exposed animal.In addition, while trying to ascertain the stress-induction status of atrazine, it is very important to consider the environmentally relevant concentration found in drinking water from rural agricultural communities to which the inhabitants may be directly exposed.
Meanwhile, in our first report of findings from this study where we carried out a survey to determine the concentration of atrazine in water from 69 hand-dug wells (HDW), 40 boreholes (BH) and 4 streams in 6 communities (Awa, Oru, Ijebu-Igbo, Ago-Iwoye, Mamu, Ilaporu) of Ijebu-North Local Government Area, Southwest Nigeria, the concentration of atrazine recorded in each water sample was subjected to human health risk associated with its exposure via dermal contact and ingestion.in adults and children as well as neurotoxicity assessment.We reported the highest concentration range of 0.01-0.08mg/L for atrazine in water from the communities.We concluded that atrazine at 0.01, 0.03 and 0.04 mg/L concentrations may not pose any threat to brain function, but concern should be raised at 0.08 mg/L (Owagboriaye et al. 2022).In the follow-up study presented here, we aimed to determine the effect of the atrazine concentration on the HPA axis by focusing on stress-mediated hormones, oxidative stress parameters and butyryl-cholinesterase (BuChE) in the blood of albino rats.

Description of the study area
We carried out this study in the Ijebu-North local government area, one of the 20 local government areas in Ogun State.Ijebu-North comprises six rural farming communities (Awa, Oru, Ijebu-Igbo, Ago-Iwoye, Mamu, Ilaporu), each with a farm settlement.According to the report of the National Population Commission (NPC) in the year 2016, the local government has a population projection of 390, 200 and a total land area of 967 km 2 (NPC, 2016).

Collection of water sample
We adopted the method of the US Geological Survey (Koterba et al. 1995) as modified in Owagboriaye et al. (2022) for the collection of 69 HDW, 40 BH and 4 streams from the local government (Figure 1).The collection of water samples was maintained within at least a 400-meter distance from each sampling point throughout the community as previously described (Owagboriaye et al. 2022).Considering the fact that atrazine is mostly used during the maize planting season, all the water samples were collected between the months of May to July 2021.The number of HDW, BH and streams sampled from each of the communities is shown in Table 1.However, all the maps of each of the communities showing the sampling points are shown in Supplementary Figures 1(a-g).We recorded the depth of the HDW (less than 12 m) as well as the coordinates of each sampling point (See supplementary Table 1a-g).The method of water collection, transportation and analysis was in accordance with Owagboriaye et al. (2022).The highest concentrations of atrazine detected in water from a community were orally exposed to male albino rats in a sub-chronic toxicity study.

Determination of atrazine residue in the water sample
We employed the modified analytical method for the monitoring of drinking water for contaminants to determine the level of atrazine in the water sample (Huang et al. 2003, US EPA 2009).The method was modified in Owagboriaye et al. (2022).We weighed 10 mg of analytical standard (Sigma-Aldrich, St. Louis, MO, USA) into a 100 mL flask to prepare a stock standard of atrazine.Extraction was done using Solid-Phase Extraction (SPE) technique with the C18 SPE cartridge that was conditioned under gravity with 10 mL of methanol and 10 mL of deionized water as described in Owagboriaye et al. (2022).A total of 200 mL of the water sample was pumped through the cartridge (at a 10 mL/min flow rate) after which, it was washed with deionized water, subjected to a vacuum system and dried with nitrogen gas.The compound was eluted with 2 mL of methanol and the extract was dried at 40 C on a rotary evaporator as well as a stream of nitrogen gas.The final extract was reconstituted in acetone to a volume of 1.0 mL and analyzed for atrazine concentration on gas chromatography (7890 A Model) coupled with Mass Selective Detector (MSD Model 5975 C).The oven temperature was initially set at 110 C for 2 minutes and gradually increased to 2500 C for 8 minutes.A sample volume of 1 m/L was injected and separated on Agilent technologies HP5MS column (30 m X 0.25 mm X 0.320 mm).We used Helium gas at 65 psi as the carrier gas.The peak areas were quantified and identified by comparing them with the standard, which was used to prepare the calibration standard solutions (Owagboriaye et al. 2022).

Experimental animal and design
We used a total of thirty (30) adult male albino rats (140 ± 10 g) for this study.We acclimatized the rats for 7 days in our laboratory under 25 ± 5 C and 65 ± 5% relative humidity before the exposure regime.The rats were given standard laboratory rat chow (Animal Care Ltd) and clean drinking water ad libitum.We randomly assigned the rats into five groups and exposed to distilled water (control) and the highest atrazine (PESTANAL, Sigma-Aldrich St. Louis, MO, USA: Purity-98.2%)concentration of 0.01, 0.03, 0.04 and 0.08 mg/L recorded in the water from each of the communities for a period of 12 weeks.We followed the guidelines of the ethical committee in the animal care unit of Olabisi Onabanjo University (OOU) (approval number: OOU/ SCIENG/EC/0003/140621) and regulation CEE 86/609 to carry out the experiment.

Sample collection and preparation
Blood samples were collected from the rats into plain sample tubes by retro-orbital sinus with micro hematocrit tube the following day after the last day of exposure.The blood samples were centrifuged at 2500 Âg for 10 min at 4 C and the sera obtained were stored at À20 C until used for the hormonal and oxidative stress parameter assays.

Hormonal Assay
The sera obtained were analyzed with commercially available ELISA kits for aldosterone, corticosterone (Enzo life sciences, PA) and ACTH (Eagle Biosciences Inc., Nashua).Aldosterone and corticosterone assays have a sensitivity of 4.87 pg/mL and 0.028 ng/mL respectively with detection range of 3.9-250 pg/mL and 0.03-20 ng/mL respectively.However, the sensitivity of the ACTH assay was 0.38 pg/mL and the detection range of 7.6-416 pg/mL.We followed the assay protocols and procedures as described by the manufacturer.

Determination of ROS and oxidative stress parameters in the blood of experimental rats
The level of ROS in the blood was determined by incubating 100 lL of blood aliquots with 5 lL 2 0 ,7 0 -dichlorodihydrofluorescin diacetate (DCFH-DA) at 37 C for 60 minutes as previously described in P erez-Severiano et al. ( 2004) and Owagboriaye et al. (2022).The thiobarbituric acid reactive substance (TBARS) assay described in Okhawa et al. (1979), which involves the measurement of malondialdehyde (MDA) was employed for the determination of lipid peroxidation.
The method of Hassan and Barakat (2008) was followed for the determination of reduced glutathione (GSH) concentration.Catalase (CAT) activity determination was in accordance with Aebi (1984) and a 1 mmol decrease in hydrogen peroxide/minute denotes one unit of the enzyme.The activity of plasma butyrylcholinesterase or BuChE in the blood was in accordance with Ellman et al. (1961) using acetylthiocholine iodide (30 ll final concentration) as substrate and 5,5-dithiobis-2-nitrobenzoeic acid (DTNB; 200 ll final concentration).Assay tubes were completed to 1 ml with sodium phosphate buffer (pH 8) as described by Saxena et al. (2018).The enzyme activity was calculated relative to protein concentrations.

Statistical analysis
Statistical analysis of the data was carried out with version 20.0 of the IBM-SPSS Statistical Package (IBM Corp., 2011).The mean values comparison was done through the Analysis of Variance (ANOVA) and the results were presented as Mean ± Standard Error of Mean (SEM).We used the Student-Newman-Keuls (SNK) to carry out the post hoc test and a significant level was set at a probability value less than 0.05.

Results
The concentration of atrazine recorded in water from the communities in Ijebu-North LGA  the BH and streams.The highest atrazine concentration of 0.08 mg/L was observed in HDW from the Ago-Iwoye farming community.Varying atrazine concentrations were also found in HDW from Ijebu-Igbo (0.03 mg/L), Awa (0.04 mg/L) and Mamu (0.04 mg/L).However, Oru community recorded the highest atrazine concentration of 0.01 mg/L in its HDW.

Levels of corticosterone, aldosterone and adrenocorticotropic hormone in the blood
Serum levels of corticosterone, aldosterone and ACTH in rats exposed to atrazine concentrations in drinking water from Ijebu-North, Southwest Nigeria are represented in Table 3. Serum levels of corticosterone and aldosterone were observed to increase with an increase in atrazine concentration.But the increase was only significant (p < 0.05) at 0.08 mg/L atrazine concentration compared to other groups.There were no significant differences (p > 0.05) in levels of corticosterone and aldosterone of rats exposed to 0.01, 0.03 and 0.04 mg/L concentrations of atrazine compared to control.However, serum ACTH of the control and those exposed to the varying concentrations of atrazine were not significantly different (p > 0.05).

The concentration of reduced glutathione (GSH) and activity of catalase in the blood
The concentration of GSH and catalase activity in the blood of rats exposed to atrazine concentrations in drinking water from Ijebu-North, Southwest Nigeria are presented in Figure 2.There was no significant difference (p > 0.05) in the GSH concentration in control and rats exposed to 0.01, 0.03, 0.04 and 0.08 mg/L concentrations of atrazine.Although GSH concentration was highest at 0.01 mg/L of atrazine but lowest at 0.08 mg/L.On the other hand, catalase activity was observed to significantly (p < 0.05) increase in rats exposed to atrazine at 0.03 mg/L, this was followed by those exposed to 0.04 mg/L of atrazine compared to control.There were no significant differences (p > 0.05) in the catalase activity between rats exposed to 0.01 and 0.08 mg/L as well as between control and 0.04 mg/L of atrazine.

Levels of reactive oxygen species (ROS) and lipid peroxidation in the blood
Levels of ROS and lipid peroxidation in the blood of male albino rats exposed to atrazine concentrations in drinking water from Ijebu-North, Southwest Nigeria are represented in Figure 3. ROS production was significantly (p < 0.05) increased in the rats exposed to atrazine at 0.08 mg/L compared to other groups.However, there was no significant difference (p > 0.05) in the level of ROS recorded in the control rats and those exposed to 0.01 mg/L, 0.03 mg/l and 0.04 mg/L concentrations of atrazine.Lipid peroxidation was observed to increase in the experimental rats with an increase in the concentration of atrazine exposure, but the increase was not significant (p > 0.05) compared to control.

The activity of butyrylcholinesterase (BuCHE) in the experimental rat
Figure 4 shows the activity of butyrylcholinesterase in rats exposed to atrazine concentrations in drinking water from Ijebu-North, Southwest Nigeria.There was no significant (p > 0.05) difference in the enzyme activity in the control rats and those exposed to the varying concentrations of atrazine.

Discussion
In this study, we carried out a survey of atrazine residue in drinking water sourced from the six farming communities of Ijebu-North LGA, Southwest Nigeria as well as the implication of the atrazine concentration on the hypothalamic-pituitary-adrenal axis in a subchronic toxicity study using experimental male albino rats.Our study shows that atrazine residues in the water from Ilaporu and Oru farming communities were lower than the permissible limits set by the USEPA and Canada.However, residues of atrazine in HDW water from Mamu and Awa farming  communities were higher than the USEPA limit, but below that of Canada.Meanwhile, HDW water from sampling point 1 in the Ago-Iwoye community contains atrazine residue that is above the limit of USEPA and Canada.This clearly shows that HDW water from Mamu, Ago-Iwoye and Awa communities is more polluted with atrazine than the HDW water from Oru, Ijebu-Igbo and Ilaporu communities.The higher level of atrazine observed in the HDW water from Awa, Mamu, and Ago-Iwoye could be attributed to the possible higher use of atrazine in these farming communities since a high level of atrazine detected in some sites was attributed to the higher use of the herbicide (Sun et al. 2017).Moving away from the farm settlement in each community resulted in slight variation and reduction in the concentration of atrazine in water from each sampling point.The reason behind this variation or reduction is unknown, but we suspect the depth of the HDW, geographical structure or level of agricultural activity in the area.These have been documented to contribute to the distribution or level of atrazine found in an area (Sun et al. 2017, Almasi et al. 2020).
In this study, we only observed higher serum levels of corticosterone and aldosterone in rats exposed to atrazine at 0.08 mg/L.There were no significant differences in levels of corticosterone and aldosterone in rats exposed to 0.01, 0.03 and 0.04 mg/L concentrations of atrazine compared to control.It is known that the release of corticosterone is associated with a physiological response to stress (Jacobson 2005, De Kloet and Rinne 2007, Franklin et al. 2012).Aldosterone also maintains the homeostatic balance of the extracellular fluid (Miller and Harley 1996) and its elevation may result in metabolic and physiological disorders.Therefore, the observed increase in serum corticosterone and aldosterone of rats exposed to atrazine at 0.08 mg/L in this study may suggest induction of stress.Meanwhile, the secretion and regulation of corticosterone and aldosterone are under the control of ACTH through the stimulation of the adrenal gland (Yang andMa 2009, Jovanovic et al. 2011).However, serum ACTH of the control and those exposed to the varying concentrations of atrazine were not significantly different in this study.Since atrazine at 0.08 mg/L concentration was observed to significantly increase the serum levels of corticosterone and aldosterone in the exposed rats, it is clear that atrazine at 0.08 mg/L has an effect on the hypothalamic-pituitary-adrenal axis of the exposed animal.However, the insignificant change in the level of ACTH may indicate a direct effect of atrazine on the adrenal gland (or some atrazine-induced intermediate) or consequences of oxidative stress effects on the adrenal gland.Our finding is, in part, supported by Foradori et al. (2018) who observed increased serum corticosterone in rats following atrazine exposure, but at a much higher dose range of 75 to 200 mg/kg.In addition, Zimmerman et al. (2021) recently displayed elevated levels of aldosterone in female Sprague Dawley rats exposed to 100 mg/kg body weight of atrazine only after stimulation with angiotensin II, but the animals in the current study were not stimulated.However, our findings match Fraites et al. 2009 who demonstrated elevated corticosterone in animals treated with atrazine without a significant elevation of ACTH.
Antioxidant defence focuses on the protection of cells by scavenging the ROS generated through oxidation in the body (Pastore et al. 2003).An imbalance between the production of ROS and antioxidant defence in the body results in oxidative stress, which damages lipids (lipid peroxidation), proteins, carbohydrates and nucleic acids.Although ROS was observed to increase in the blood of rats exposed to atrazine in this study, an increased CAT activity observed in the rats signifies the capability of the enzyme against the increased ROS concentration in the blood (Spasic' et al. 1993).Singh et al. (2011) and Qian et al. (2008) found increased activity of CAT as a compensatory response to oxidative stress by atrazine.This claim is evidenced by the insignificant increase in the level of blood MDA observed in the rats exposed to atrazine and this enables us to suggest that the antioxidant defence system in the blood provides protection against the ROS induced by the herbicide.Therefore, oxidative stress may not be induced in the normal blood physiology of animals exposed to atrazine at 0.01, 0.03 and 0.04 mg/L, but at 0.08 mg/L.
We observed no significant difference in BuChE activity in the control rats and those exposed to the varying concentrations of atrazine in this present study.BuChE contributes to the maintenance of cholinergic pathway integrity and the enzyme can replace acetylcholinesterase to execute a certain task (Nordberg et al. 2013).Meanwhile, evidence showed a neuroprotective role of acetylcholinesterase or its BuChE substitute by scavenging ROS and reducing lipid peroxidation in animals (Bai et al. 2014).Therefore, the insignificant difference in BuChE activity seen in the blood of the experimental rats in this study could signify that atrazine concentrations of 0.01, 0.03, 0.04 and 0.08 mg/L may not be strong enough to compromise the normal blood physiological function for toxicity.However, there is a need to determine the activity of this enzyme in the brain of the exposed animal since Schmidel et al. (2014) had earlier observed a reduction in the acetylcholinesterase activity in the brain of zebrafish exposed to 1000 lg/L of atrazine.

Conclusion
Our study shows that BH, HDW and stream waters from all the six farming communities of Ijebu-North, southwest Nigeria contain varying levels of atrazine.Water sourced from Mamu, Ago-Iwoye and Awa communities is more polluted with atrazine than the water from Oru, Ijebu-Igbo and Ilaporu communities.Atrazine at 0.01, 0.03 and 0.04 mg/L concentrations detected in the water from the communities was observed to induce antioxidant defence in the blood, which protected the tissue against stress and HPA injury in the exposed animal.However, the concern should be raised for atrazine at 0.08 mg/L, which increased the levels of corticosterone, aldosterone and ROS in the serum of the exposed rats.At present, the maximum contaminant level (MCL) for atrazine in drinking water has not been established in Nigeria despite the increasing use of the herbicide.Our results reported here on the residue of atrazine in water from the six farming communities of Ijebu-North LGA could therefore serve as baseline data for the establishment of MCL of atrazine in Nigeria.Although the number of water samples collected and analyzed in the present study may not be enough, we recommend an additional study focusing on a larger number of water samples, which can provide large data that can be used to evaluate the dose-response relationship and calculate the benchmark dose low limit (BMDL) or the low observed adverse effect level (NOAEL) from where the safe level of atrazine in water can be established.Meanwhile, we call on the regulatory bodies of the Federal Government of Nigeria to quickly provide adequate measures on the increasing use of atrazine in the rural agricultural communities and safeguard the health of rural dwellers, especially those in Ijebu-North southwest, Nigeria.

Figure 1 .
Figure 1.Map of Ijebu-North LGA showing the sampling point.

Figure 2 .
Figure 2. Concentration of GSH and catalase activity in the blood of male albino rat exposed to atrazine concentrations in drinking water from Ijebu-North, Southwest Nigeria.Error bars represents standard deviation; Ã Mean values significantly different (p < 0.05) from the control.

Figure 3 .
Figure 3. Levels of ROS and MDA in the blood of male albino rat exposed to atrazine concentrations in drinking water from Ijebu-North, Southwest Nigeria.Error bars represents standard deviation; Ã Mean values significantly different (p < 0.05) from the control.

Figure 4 .
Figure 4. Butyrylcholinesterase activity in the blood of rats exposed to atrazine concentrations in drinking water from Ijebu-North, Southwest Nigeria.Error bars represents standard deviation; Ã Mean values significantly different (p < 0.05) from the control.

Table 1 .
Number of water sample collected from each of the communities.

Table 2
presents the residues of atrazine recorded in the water from the sampling point of each of the communities.A total of 22 BH, 41 HDW and all the streams showed varying concentrations of atrazine.In general, a higher residue of atrazine was found in HDW from the communities than in

Table 2 .
Concentration of atrazine (mg/L) in water from the communities in Ijebu-North Local Government of Ogun State, Nigeria.

Table 3 .
Levels of corticosterone, aldosterone and Adrenocorticotropic hormone (ACTH) in the blood of male albino rat exposed to atrazine concentrations in drinking water from Ijebu-North, Southwest Nigeria.