Ultrasound measurements of right hemidiaphragm thickness are feasible and highly reproducible in ventilated patients. At clinically relevant inspiratory volumes, diaphragm thickening reflects muscular contraction and not passive inflation. This technique can be reliably employed to monitor diaphragm thickness, activity, and function during mechanical ventilation.

The pesticide DDT [1,1,1-trichloro-2,2-bis(chlorodiphenyl)ethane] is 1 of the 12 persistent organic pollutants (POPs) under negotiation at the Stockholm Convention to restrict or ban their production and use because of their toxicity, resistance to breakdown, bioaccumulation, and potential for being transported over long distances. DDT has estrogenic potential, and the main metabolite, p,p9-dichlorodiphenyl-dichloroethylene (p,p9-DDE), is a potent antiandrogen. In response to mounting evidence on the endocrine-disrupting influence of environmental chemicals on human health, this epidemiological study was initiated to test the hypothesis that nonoccupational exposure to DDT affects male reproductive parameters. In a cross-sectional study, healthy male subjects (n 5 311) between 18 and 40 years (23 6 5) of age were recruited from 3 communities in an endemic malaria area in which DDT is sprayed annually. A semen analysis according to World Health Organization (WHO) standards was performed. The Hamilton Thorne Computer Assisted Sperm Analysis (CASA) system was simultaneously used to determine additional sperm motility parameters. Blood plasma samples were assayed for p,p9-DDT and metabolites as a measure of exposure. The exposure levels were expressed as lipid-adjusted p,p9-DDT and p,p9-DDE values. The mean p,p9-DDT and p,p9-DDE concentrations were 90.23 mg/g (6102.4) and 215.47 mg/g (6210.6), respectively. The multivariate linear regression analyses indicated that mean CASA motility was lower with a higher p,p9-DDE concentration (b 5 20.02, P 5 .001) and the CASA parameter beat cross-frequency (BCF) was higher with a higher p,p9-DDT concentration (b 5 0.01, P 5 .000). There was also a statistically significant positive association between percent sperm with cytoplasmic droplets and p,p9-DDT concentration (b 5 0.0014, P 5 .014). The ejaculate volume (mean 1.9 6 1.33 mL) was lower than the normal range ($2.0 mL) according to WHO, and a significant decrease with increasing p,p9-DDE values was seen for both square roottransformed volume (b 5 20.0003; P 5 .024) and count (b 5 20.003; P 5 .04). Although there were no associations between either p,p9-DDT or p,p9-DDE concentrations and the rest of the seminal parameters, the incidence of teratozoospermia (99%; normal sperm ,15%) was high. Twenty-eight percent of the study group presented with oligozoospermia (,20 6 10 6 sperm/mL), which had a significant positive association with p,p9-DDE (odds ratio [OR] 5 1.001, P 5 .03). There was a significant positive association between participants with asthenozoospermia (32%) and p,p9-DDT (OR 1.003, P 5 .006) and p,p9-DDE (OR 1.001, P 5 .02). The results imply that nonoccupational exposure to DDT is associated with impaired seminal parameters in men. The high exposure levels of p,p9-DDT and p,p9-DDE are of concern because these levels could have far-reaching implications for reproductive and general health.

Studies of low to moderate level lead exposures have reported mixed findings regarding the risk of spontaneous abortion, despite lead's abortifacient properties at very high doses. To evaluate the risk of spontaneous abortion from low or moderate lead exposures, a nested case-control study was conducted within a cohort of pregnant women in Mexico City, 1994-1996. During their first trimester, 668 women enrolled, were interviewed, and contributed blood specimens. Pregnancies were followed by home visits or telephone calls. Spontaneous abortions before week 21 (n = 35) were matched with pregnancies that survived beyond week 20 (n = 60) on maternal age, hospital, date of enrollment, and gestational age at enrollment. Mean blood lead levels were 12.03 microg/dL for cases and 10.09 microg/dL for controls (p = 0.02). Odds ratios for spontaneous abortion comparing 5-9, 10-14, and > or =15 microg/dL with the referent category of <5 microg/dL of blood lead were 2.3, 5.4, and 12.2, respectively, demonstrating a significant trend (p = 0.03). After multivariate adjustment, the odds ratio for spontaneous abortion was 1.8 (95% confidence interval = 1.1, 3.1) for every 5 microg/dL increase in blood lead. Low to moderate lead exposures may increase the risk for spontaneous abortion at exposures comparable to US general population levels during the 1970s and to many populations worldwide today; these are far lower than exposures encountered in some occupations.

ABSTRACT:In response to mounting concerns about the endocrine-disrupting influence of environmental chemicals on human health, this epidemiological study was initiated to test the hypothesis that nonoccupational exposure to the estrogenic pesticide 1,1,1-trichloro-2,2-bis(chlorodiphenyl)ethane (DDT) affects male reproductive parameters. One hundred and sixteen men aged 27 years (SD ϭ 8.2) living in malaria endemic-areas in Chiapas (Mexico), where DDT was sprayed until 2000, participated in a cross-sectional study. Semen analyses were conducted according to World Health Organization methods and a quality control program was followed. DDT exposure was defined as the level of blood plasma p,pЈ-dichlorodiphenyl dichloroethylene (DDE), the major metabolite of DDT. The p,pЈ-DDE concentration adjusted for total lipids was 100 times higher than that reported for nonexposed populations at 45 plus or minus 32 g/g (mean Ϯ SD). Crude regression analysis showed that several sperm motion parameters, including the percentage of motile sperm, decreased with higher p,pЈ-DDE concentrations (␤ ϭ Ϫ8.38; P ϭ .05 for squared motility), and the percentage of sperm with morphological tail defects increased with higher plasma p,pЈ-DDE concentration (␤ ϭ 0.003; P ϭ .017). Insufficient sperm chromatin condensation was observed in 46.6% of participants, and the most severe category of incomplete DNA condensation was also positively correlated with p,pЈ-DDE concentration (r ϭ .223; P ϭ .044). Therefore, nonoccupational exposure to DDT, as assessed by plasma p,pЈ-DDE concentrations, is associated with poorer semen parameters in men, indicating adverse effects on testicular function and/or the regulation of reproductive hormones. Previously, a causal role of environmental toxicants in human male infertility has been lacking because observed effects have been the result of unusually high exposures, either occupationally or as a result of industrial accidents, resulting in unprecedented controversy (reviewed by Cheek & McLachlan, Environmental hormones and the male reproductive system. J Androl. 1998;19:5). This is the first epidemiological study demonstrating effects after nonoccupational exposures to DDT. Based on these findings, the effect of DDT on male reproductive health should not be ignored.

Study Type – Symptom prevalence (retrospective cohort)
Level of Evidence 2b OBJECTIVE To determine the risk of external urogenital birth defects (UGBDs) in newborn boys from a malarial area currently sprayed with technical 1,1,1‐trichloro‐2,2‐bis(4‐chlorophenyl) ethane (DDT), as increased fetal oestrogenic or anti‐androgenic exposure might be involved in the pathogenesis of increased prevalence of human male reproductive tract anomalies, and DDT and metabolites interact with both these receptors. SUBJECTS AND METHODS We examined 3310 newborn baby boys and recorded external UGBDs. RESULTS Of the newborn boys 10.8% (357) had UGBDs; a multivariate logistic model showed that mothers who lived in villages sprayed with DDT between 1995 and 2003 had a significantly greater chance (33%) of having a baby with a UGBD than mothers whose homes were not sprayed (odds ratio 1.33, 95% confidence interval 1.04–1.72). Being a homemaker instead of being employed further significantly increased the risk of having a baby with a UGBD by 41% (odds ratio 1.41, 1.13–1.77). CONCLUSIONS Maternal exposure to DDT by living in a DDT‐sprayed village was associated to having male offspring with one or more UGBDs. Monitoring the impact of indoor residual spraying on human and environmental health is imperative if DDT is being used, especially as climate change raises concerns about the global spread of malaria. Integrating adequate indoor residual spraying measures by malarial vector control programmes, and increased public awareness to limit personal exposure, are crucial components that need to be addressed.