## 3 Results and Discussion
### Cd Exposure Schemes
#### 3.2.2 Cd Exposure of Dams during Lactation Period
Thus, this scheme ensured that the effect observed in offspring was caused  
\begin{table}
\begin{tabular}{p{113.8 pt} p{113.8 pt} p{113.8 pt} p{113.8 pt}} \hline \hline
**Strain (\(n\))** & & & \\
**Dose/Concentration, Admin Route Exposure Period** & **Collection Time Organ Analyzed** & **Results** & **Year Author** \\ \hline \begin{tabular}{} \end{tabular}  \\  
by the Cd in milk, avoiding effects generated by gestational Cd exposure. In this scheme, neurological effects in sucking pups, such as increased motor activity [19], disturbances in the serotonergic system [21], and impairment in memory [27], were described at low Cd doses (4.8, 0.9 and 1.2 mg Cd/kg b.w., respectively). Increased motor activity was observed in offspring at PND 29 after 17 days of Cd exposure, disturbances in the serotonergic system was described at PND 51 after 19 Cd exposure days, and memory impairment was determined at PND 100 after seven days of Cd exposure. Interestingly, a low dose (1.2 mg Cd/kg b.w.) administered for seven days caused neurological effects on offspring at 100 days after birth, suggesting that Cd exposure only during lactation is sufficient to produce alterations in neuronal functions. In addition, biochemical effects were determined in offspring at PND 19 and 120 after Cd exposure of dams for 17 and 10 days, respectively. Results show fatty acid metabolism altered in brain [20] and increased oxidative stress evaluated by malondialdehydedehyde determination in plasma and erythrocytes [13]. [PERSON] et al. evaluated oxidative stress in both pregnancy and lactation scheme. After results comparison, they concluded that Cd-effects in plasma and erythrocytes were pronounced in lactation exposure than in pregnancy, suggesting that only lactation exposure can induce effects on the offspring. Other effects such as morphological changes in the mouth of the suckling pups [22; 23; 24; 25] and decrease in body, kidney, and spleen weights of female offspring [26] were evaluated. Changes in mouth tissue were described in four papers that coincided in the experimental features such as Cd concentration of 300 mg/L administered to Wistar rats in drinking water from PD to PND 21, whereas decrease in body and organs weights were reported at lower Cd concentration (10 mg/L) in drinking water. Accumulation of Cd in kidneys of suckling pups [19; 28], and immunotoxic effects were also reported [26].Although, [PERSON] et al. [19] and [PERSON] and [PERSON] [28] agree that Cd accumulates in kidney, they described different experimental features. While [PERSON] et al. administered Cd in drinking water at 25 mg/L (equivalent to 4.8 mg/k b.w.) for 17 days, [PERSON] and [PERSON] exposed dams to \({}^{109}\)Cd 300 \(\mu\)g/kg b.w. intravenously for 14 days. The Cd accumulation in kidney evaluated in offspring at PND 29 and 16 suggests that Cd even at low doses is transferred by breastfeeding to the offspring from the beginning of the lactation period until weaning. All the effects observed in lactation exposure scheme confirm that Cd is transferred by breast milk from dams to pups, highlighting the importance of studying the mechanisms and effects of Cd exposure at low and high doses on infants.