Effect of endosulfan on male reproductive development - Children's Health

Environmental Health Perspectives, Dec, 2003 by Habibullah Saiyed, Aruna Dewan, Vijay Bhatnagar, Udyavar Shenoy, Rathika Shenoy, Hirehall Rajmohan, Kumud Patel, Rekha Kashyap, Pradip Kulkarni, Bagalur Rajan, Bhadabhai Lakkad

Statistical analysis. The statistical software SPSS, release 6.1.4 (SPSS Inc., Chicago, IL, USA), was used for statistical analysis of data and for making graphs. For the multiple regression analysis, age and aerial exposure to endosulfan (AEE; study = 1, control = 0) were taken as independent variables, and parameters of SMR and serum hormone levels were taken as dependent variables. Exact age in years on the date of examination was used as the age variable.

We used the following multiple regression equation: SMR score = [b.sub.0] [b.sub.1] age [b.sub.2] x AEE, where [b.sub.0] is the regression constant and [b.sub.1] and [b.sub.2] are the regression coefficients of age and exposure, respectively, fitted for SMR scores of pubic hair, testes, and penis. Similarly, multiple regression equations were fitted for testosterone, LH, and FSH levels.

Results

Table 1 shows the comparison of the mean [ or -] SD values of the age and some of the growth-related basic parameters in study and control subjects participating in the SMR study. There are no statistically significant differences in the mean values of these parameters in two groups. The mean values of height, weight, body mass index, and skin-fold thickness of the nonparticipating subjects in study and control groups with respect to age were also comparable, indicating that the nonparticipation of the subjects may not have had significant effects on the outcome of the study.

Clinical examination revealed six (5.1%) cases of congenital malformations in the study group, consisting of undescended testis (two), congenital hydrocele (three), and congenital inguinal hernia (one), and only one case (1.1%) of congenital inguinal hernia in the control group. The differences in prevalence of congenital malformation were statistically nonsignificant.

SMR score. A summary of the multiple regression analysis of parameters of SMR score on age and AEE is presented in Table 2. The values of [R.sup.2] corresponding to SMR of pubic hair, testes, and penis are 0.48, 0.43, and 0.43, respectively, are statistically significant (p < 0.001), and indicate that considerable proportion of variance of SMR scores can be attributed to age and AEE. The statistically significant negative regression coefficient ([b.sub.2]) of AEE in all three equations signifies delayed sexual maturity in the study group compared with the control group. As expected, age had a significant positive regression coefficient.

These effects of AEE are further elaborated graphically in Figures 3-5. In Figure 3, the findings for SMR for pubic hair is plotted against age for study and control individuals. The regression lines drawn for the study and control groups indicate that the SMR score for the study group is lower for the same age. Similar observations were made for the SMR score for testicular (Figure 4) and penis development (Figure 5).

[FIGURES 3-5 OMITTED]

Serum hormone levels. Table 3 shows the summary of the multiple regression analysis of serum testosterone levels against age, AEE, and serum LH levels. The value of [R.sup.2] is 0.61, which means that 61% of the variations observed in serum testosterone levels can he explained on the basis of age, AEE, and serum LH levels. Very small p-values (< 0.001 in all cases) of the regression coefficient indicate that statistically these parameters are significant in determining the serum testosterone levels. The positive sign of the regression coefficient for age and LH indicates that with increase in age and serum LH levels, there is an increase in the serum testosterone levels. This is a well-known physiologic fact. On the other hand, the regression coefficient for AEE has a negative sign, which means the serum testosterone levels of individuals belonging to the study group are statistically lower than expected from age and serum LH levels. The levels of FSH were slightly higher for the age in study group; however, the differences were statistically nonsignificant.