Table 4.
Epidemiological Studies of DBP and Other Phthalates
| References | Discussed in Draft TR | Type of Study (Number of Participants) | Exposure Measures | Outcomes and Findings |
|---|---|---|---|---|
| Murature et al. 1987 | √ | Cross sectional College student volunteers (n=21) |
DBP concentration in cellular fraction of ejaculate | Strong negative correlation (r = −0.6 and −0.7) between sperm density and DBP concentration |
| Duty et al. 2003a | √ | Cross-sectional Men at fertility clinic (n=168) |
Urinary levels of several phthalate metabolites. | Dose response relation observed between increased urinary MBP and poor sperm motility (statistically significant trend) and sperm concentration. Similar findings for MBzP. |
| Duty et al. 2003b | √ | Cross-sectional Men at fertility clinic (n=168) |
Urinary levels of several phthalate metabolites | MBP was not found to be associated with sperm DNA integrity (using neutral comet assay). |
| Duty et al. 2004 | √ | Cross-sectional Men at fertility clinic (n=220) |
Urinary levels of several phthalate metabolites. | Suggestive negative dose-response relationships between MBzP, MBP, and MEHP with VCL and VSL; MEP negatively associated with LIN but positively associated with VCL and VSL. |
| Swan et al. 2005 | √ | Pregnancy cohort follow-up (n= 85, males only) | Phthalate metabolites in prenatal urine samples | Statistically significant increased odds of reduced AGI (AGD normalized by body weight) in male infants with increasing levels of maternal urinary MBP and several other phthalate metabolites (association with MBP levels strongest and of greatest magnitude) |
| Main et al. 2006 | √ | Case-control (n=130; 62 cases, 68 controls) | Phthalate metabolites in breast milk (1 −3 months postnatal) | No associations found with cryptochidism. MBP was negatively correlated with free testosterone. MBP and other metabolites were positively correlated with SHBG and LH: free testosterone ratio. MiNP was associated with LH. |
| Hauser et al. 2006 | Cross-sectional Men at fertility clinic (n=463) |
Urinary concentrations of several DBP and DEHP metabolites | Statistically significant dose response gradient observed for MBP and low sperm concentration and reduced motility | |
| Swan et al. 2008 | Reanalysis/expansion of 2005 study (n=106) Outcomes: AGD (adjusted for age and weight percentile), penile width and testicular descent |
Assessed individual and joint exposure to phthalate metabolites in prenatal urine samples | Higher metabolite concentrations (individual metabolites and combined exposures) associated with shorter AGD; higher metabolite concentrations associated with increased probability of incomplete testicular descent; MEHP and sum of DEHP metabolites associated with penile width | |
| Swan et al. 2009 | Pregnancy cohort follow-up Subset of boys (n=74) and girls (n=71) |
Phthalate metabolites in prenatal urine samples | Levels of prenatal MBP and MiBP associated with reduced masculine play in boys; no associations observed for girls |
Abbreviations: AGD, anogenital distance; AGI, anogenital index; DBP, dibutyl phthalate; DNA, deoxyribonucleic acid; LH, lutenizing hormone; LIN, sperm linearity; MBP, mono-butyl phthalate; MBzP, mono-benzyl phthalate; MEP, mono-ethyl phthalate; MiNP, mono-isononyl phthalate; MiBP, mono-isobutyl phthalate; PK, pharmacokinetic; SHBG, sex-hormone binding globulin; VCL, sperm curvilinear velocity; VSL, sperm straight-line velocity.