Sex ratio in the offspring of male radiologists

Association between occupational testicular radiation exposure and lower male sex ratio of offspring among orthopedic surgeons

Background

Exposure to occupational radiation can lower the male sex ratio. However, specific radiation exposure to the testes has not been evaluated.

Objective

This study aimed to examine the association between testicular radiation exposure and lower male sex ratio in children.

Methods

A comprehensive questionnaire survey was administered to 62 full-time male doctors with children aged < 10 years at 5 hospitals. Based on the possibility of testicular radiation exposure 1 year before the child’s birth, participants were assigned to 3 groups as follows: RT (orthopedic surgery), RNT (cardiology/neurosurgery), and N (others). Intergroup differences in the proportion of female children were ascertained, and the female sex ratio (number of female/total number) of each group was compared against the standard value of 0.486. Multivariate logistic regression analysis with a generalized estimating equation was used to model the effects on the probability of female birth while controlling for the correlation among the same fathers.

Results

The study population included 62 fathers and 109 children, 49 were female: 19/27, 11/30, and 19/52 in the RT, RNT, and N group, respectively; the RT group had the highest proportion of females (p = 0.009). The p values for comparisons with the standard sex ratio (0.486) were 0.02, 0.19, and 0.08 for the RT, RNT, and N groups, respectively. Based on the N group, the adjusted odds ratios for the child to be female were 4.40 (95% confidence interval 1.60–2.48) and 1.03 (0.40–2.61) for the RT and RNT groups, respectively.

Conclusions

Our results imply an association between testicular radiation exposure and low male sex ratio of offspring. Confirmatory evidence is needed from larger studies which measure the pre-conceptional doses accumulated in various temporal periods, separating out spermatogonial and spermatid effects.

The hidden risk of ionizing radiation in the operating room: a survey among 258 orthopaedic surgeons in Brazil

Background

This study aims to assess orthopaedic surgeon knowledge in Brazil about ionizing radiation and its health implications on surgical teams and patients.

Methods

A 15-question survey on theoretical and practical concepts of ionizing radiation was administered during the 23rd Brazilian Orthopaedic Trauma Association annual meeting. The survey addressed issues within orthopedic surgery, such as radiation safety concepts, protection, exposure, as well as the participant gender. Participants were either orthopedic surgeons or orthopedic surgery residents working at institutions in Brazil.

Results

One thousand surveys were distributed at the moment of the meeting registration, and 258 were answered completely (25.8% response rate). Only 5.8% of participants used basic radiation protection equipment; 47.3% used a dosimeter; 2.7% reached the annual maximum permissible radiation dose; 10.5% knew the period of increased risk to fetal gestation; 5.8% knew the maximum permissible radiation dose during pregnancy; 58.5% knew that the hands, eyes, and thyroid are the most exposed areas and at greater risk of radiation-related lesions; 25.2% knew the safe distance from a radiation-emitting tube is 3 m or more; 44.2% knew the safest positioning of the radiation-emitting tube; 25.2% knew that smaller tubes emit greater radiation at the entrance dose to magnify the image; and 55.4% knew that the surgery team receives more scattered radiation in surgical procedures performed on obese patients.

Conclusion

This study revealed inadequate theoretical and practical knowledge about radiation exposure among orthopaedic surgeons in Brazil. Only a minority of orthopaedic surgeons used basic radiation protection equipment. No significant differences in knowledge were found when comparing all orthopedic surgery specialties. Our findings indicate an urgent need for education to increase knowledge among orthopaedic surgeons about the hazards of ionizing radiation. Personal protection and implementation of the ALARA (as low as reasonably achievable) protocol in daily practice are important behaviors to prevent the harmful effects of ionizing radiation.

Paternal occupational exposure to chemicals and secondary sex ratio: results from the Japan Environment and Children's Study

BACKGROUND

Declining proportions of male births have been reported in several industrialised countries. Previous reports have shown that exposure to certain chemical substances might influence the secondary sex ratio (SSR). We assessed the associations between paternal occupational exposure to chemicals and the SSR of their children using the Japan Environment and Children's Study (JECS), a large-scale birth cohort study.

METHODS

Data on paternal occupational exposure to various agents and other covariates were collected using a self-administered questionnaire to partners of pregnant female participants enrolled in the JECS. After adjusting for potential confounders, multivariable modified Poisson regression models were used to evaluate associations between paternal occupational exposures and the SSR of their children. This study was registered in the UMIN Clinical Trials Registry, number UMIN000030786.

FINDINGS

The JECS study gathered data on 103 062 pregnancies, 104 065 fetuses, and 51 898 partners of pregnant women. Among 50 283 children with data on paternal occupational exposures, 25 657 were male and 24 626 were female. The proportion of boys whose fathers were regularly occupationally exposed to insecticides was 0·445 (males, n=293; females, n=366; 95% CI 0·406-0·483), which was lower than the proportion of boys whose fathers were not exposed to insecticides. After adjusting for confounding factors, regular paternal occupational exposure to insecticides (adjusted relative risk 0·86, 95% CI 0·78-0·96) and medical disinfectants (0·95, 0·90-1·00) were significantly associated with lower SSRs among their offspring compared with the offspring of fathers not exposed to these substances.

INTERPRETATION

A declining proportion of boys could potentially be due to fathers working in environments in which they are exposed to chemicals. The associations between poorer semen quality and levels of reproductive and thyroid hormones require investigation.

FUNDING

Ministry of the Environment of Japan.

Offspring sex ratio of Iranian dentists

OBJECTIVE

To assess the impact of occupational factors on the sex ratio of dentists' children.

METHODS

A randomly selected 501 Iranian dentists participated in a telephone interview. The participants were contacted by their mobile number to answer questions about demographic variables (gender, age, marriage status), practice-related variables (year of graduation as general or specialist dentist, years of clinical work, working hours, average number of radiographs taken in a day, and spouse's job), and questions about their children (number, gender and date of birth of each child). Kruskal-Wallis and Chi-square tests served for statistical evaluation.

RESULTS

Of all participating dentists, 71 % were men, about two-thirds were 35- to 50-year olds, and 89 % were married. In total, the dentists had 768 children; about 21 % had no child. Of all the children, 54 % were boys (overall sex ratio = 1.17). The offspring sex ratio was 1.13 among male dentists, 1.50 for female dentists, and 1.44 when both parents were dentists. Higher percentages of boys were prevalent among female dentists, younger dentists, and general dental practitioners (p < 0.008).

CONCLUSION

Demographic and practice-related factors showed some impact on proportions of both sexes of dentists' children in this study. However, the result needs evaluation in further studies.

Ionizing radiation and the human gender proportion at birth--A concise review of the literature and complementary analyses of historical and recent data

It has long been known that ionizing radiation causes genetic mutations and that nuclear bomb testing, nuclear accidents, and the regular and incidental emissions of nuclear facilities enhance environmental radioactivity. For this reason, the carcinogenic and genetic impact of ionizing radiation has been an escalating issue for environmental health and human health studies in the past decades. The Windscale fire (1957) and the Chernobyl accident (1986) caused alterations to the human birth sex ratio at national levels across Europe, and childhood cancer and childhood leukemia are consistently elevated near nuclear power plants. These findings are generalized and corroborated by the observation of increased sex ratios near nuclear facilities in Austria, France, Germany, Luxembourg, Switzerland, and The Netherlands. We present a concise review of the pertinent literature and we complement our review by spatiotemporal analyses of historical and most recent data. Evidence of genetic damage by elevated environmental radioactivity is provided.

Sex ratio at birth: scenario from normal- and high-level natural radiation areas of Kerala coast in south-west India

Newborns were monitored for congenital malformations in four government hospitals located in high-level (ambient dose >1.5 mGy/year) and normal-level (≤ 1.5 mGy/year) natural radiation areas of Kerala, India, from August 1995 to December 2012. Sex ratio at birth (SRB) among live singleton newborns and among previous children, if any, of their mothers without history of any abortion, stillbirth or twins is reported here. In the absence of environmental stress or selective abortion of females, global average of SRB is about 1050 males to 1000 females. A total of 151,478 singleton, 1031 twins, 12 triplets and 1 quadruplet deliveries were monitored during the study period. Sex ratio among live singleton newborns was 1046 males (95 % CI 1036-1057) for 1000 females (77,153 males:73,730 females) and was comparable to the global average. It was similar in high-level and normal-level radiation areas of Kerala with SRB of 1050 and 1041, respectively. It was consistently more than 1000 and had no association with background radiation levels, maternal and paternal age at birth, parental age difference, gravida status, ethnicity, consanguinity or year of birth. Analysis of SRB of the children of 139,556 women whose reproductive histories were available suggested that couples having male child were likely to opt for more children and this, together with enhanced rate of males at all birth order, was skewing the overall SRB in favour of male children. Though preference for male child was apparent, extreme steps of sex-selective abortion or infanticide were not prevalent.

Increased sex ratio in Russia and Cuba after Chernobyl: a radiological hypothesis

BACKGROUND

The ratio of male to female offspring at birth may be a simple and non-invasive way to monitor the reproductive health of a population. Except in societies where selective abortion skews the sex ratio, approximately 105 boys are born for every 100 girls. Generally, the human sex ratio at birth is remarkably constant in large populations. After the Chernobyl nuclear power plant accident in April 1986, a long lasting significant elevation in the sex ratio has been found in Russia, i.e. more boys or fewer girls compared to expectation were born. Recently, also for Cuba an escalated sex ratio from 1987 onward has been documented and discussed in the scientific literature.

PRESENTATION OF THE HYPOTHESIS

By the end of the eighties of the last century in Cuba as much as about 60% of the food imports were provided by the former Soviet Union. Due to its difficult economic situation, Cuba had neither the necessary insight nor the political strength to circumvent the detrimental genetic effects of imported radioactively contaminated foodstuffs after Chernobyl. We propose that the long term stable sex ratio increase in Cuba is essentially due to ionizing radiation.

TESTING OF THE HYPOTHESIS

A synoptic trend analysis of Russian and Cuban annual sex ratios discloses upward jumps in 1987. The estimated jump height from 1986 to 1987 in Russia measures 0.51% with a 95% confidence interval (0.28, 0.75), p value < 0.0001. In Cuba the estimated jump height measures 2.99% (2.39, 3.60), p value < 0.0001. The hypothesis may be tested by reconstruction of imports from the world markets to Cuba and by radiological analyses of remains in Cuba for Cs-137 and Sr-90.

IMPLICATIONS OF THE HYPOTHESIS

If the evidence for the hypothesis is strengthened, there is potential to learn about genetic radiation risks and to prevent similar effects in present and future exposure situations.

Can environmental or occupational hazards alter the sex ratio at birth? A systematic review

More than 100 studies have examined whether environmental or occupational exposures of parents affect the sex ratio of their offspring at birth. For this review, we searched Medline and Web of Science using the terms ‘sex ratio at birth’ and ‘sex ratio and exposure’ for all dates, and reviewed bibliographies of relevant studies to find additional articles. This review focuses on exposures that have been the subject of at least four studies including polychlorinated biphenyls (PCBs), dioxins, pesticides, lead and other metals, radiation, boron, and g-forces. For paternal exposures, only dioxins and PCBs were consistently associated with sex ratios higher or lower than the expected 1.06. Dioxins were associated with a decreased proportion of male births, whereas PCBs were associated with an increased proportion of male births. There was limited evidence for a decrease in the proportion of male births after paternal exposure to DBCP, lead, methylmercury, non-ionizing radiation, ionizing radiation treatment for childhood cancer, boron, or g-forces. Few studies have found higher or lower sex ratios associated with maternal exposures. Studies in humans and animals have found a reduction in the number of male births associated with lower male fertility, but the mechanism by which environmental hazards might change the sex ratio has not yet been established.

Parental aging synergistically decreases offspring sex ratio

OBJECTIVE

The aim of this study was to investigate the effect of parental age as a factor in the observed decline in the male to female birth ratio expressed as the offspring sex ratio (OSR).

STUDY DESIGN

A prospective multicenter study was conducted from August 2005 to February 2007 at five community-based hospitals in Osaka, Japan. Pregnant women in the first trimester were recruited at their first prenatal care visit and followed until delivery. Multiple pregnancies and assisted conceptions were excluded. Periconceptional parental ages were recorded. Neonatal information was obtained at the time of delivery. Proportional distribution of categorical variables was studied using the chi(2) or Fisher's exact tests (two-tailed).

RESULTS

Data on 3,049 deliveries were available for review. OSR for the largest paternal and maternal subgroup (both, age 30-34) were male dominant (1.17 and 1.12, respectively). Paternal age > or =40 showed a smaller OSR (0.75 vs 1.17, P = 0.001). Advanced maternal age was associated with smaller OSR: age 35-39, 0.87 versus 1.12, P = 0.02; and age > or =40, 0.63 versus 1.12, P = 0.047. Synergistic effects of increasing paternal and maternal age on the OSR were observed. OSR for parental ages > or =40 were significantly smaller than ages 30-34 (0.52 vs 1.17, P = 0.029).

CONCLUSIONS

Increasing paternal ages synergistically decrease the male to female birth ratio.

Sex proportion of offspring and exposure to radiation in male invasive cardiologists

High radiation exposure among male radiologists has been reported to result in a significantly higher proportion of female offspring. This study examined whether work-related radiation exposure was associated with a higher propensity for female offspring among male interventional cardiologists. On behalf of the interventional committee of the Society for Cardiovascular Angiography and Interventions, an Internet-based questionnaire was sent to the society's 2063 members. The 402 male respondents had a total of 518 biological offspring; 48.6% of them were female. Among the 172 high-volume male diagnostic operators (those who performed >300 cases annually), there were 218 biological offspring, of whom 46.8% were female. Among the 59 high-volume male interventional operators, there were 70 biological offspring, of whom 45.7% were female. P values were nonsignificant for all three groups. In conclusion, work-related radiation exposure of male invasive and interventional cardiologists was not associated with a statistically significant preponderance of female offspring.

Female sexual maturation and reproduction after prepubertal exposure to estrogens and endocrine disrupting chemicals: a review of rodent and human data

Natural hormones and some synthetic chemicals spread into our surrounding environment share the capacity to interact with hormone action and metabolism. Exposure to such compounds can cause a variety of developmental and reproductive detrimental abnormalities in wildlife species and, potentially, in human. Many experimental and epidemiological data have reported that exposure of the developing fetus or neonate to environmentally relevant concentrations of some among these endocrine disrupters induces morphological, biochemical and/or physiological disorders in brain and reproductive organs, by interfering with the hormone actions. The impact of such exposures on the hypothalamic-pituitary-gonadal axis and subsequent sexual maturation is the subject of the present review. We will highlight epidemiological human studies and the effects of early exposure during gestational, perinatal or postnatal life in female rodents.

Adverse pregnancy outcomes in offspring of fathers working in biomedical research laboratories

BACKGROUND

Laboratory work may constitute a possible health hazard for workers as well as for their offspring, and involves a wide range of exposures, such as organic solvents, carcinogenic agents, ionizing radiation, and/or microbiological agents. Adverse pregnancy outcomes in the offspring of male employees in biomedical research laboratories are examined.

METHODS

Offspring to males employed 1970-1989 at four Swedish universities were identified via the Medical Birth Register (MBR), along with other pregnancy parameters. Offspring of fathers with laboratory work (n = 2,281) is considered exposed, and of non-laboratory employees unexposed (n = 1,909). Exposure data were obtained by questionnaires to research group leaders. Logistic regression analysis estimated odds ratios (ORs) and 95% confidence intervals (CIs).

RESULTS

Paternal laboratory work in general showed no statistically significant increased ORs concerning birth weight and/or gestational age, but work specifically with radioactive isotopes gave OR 1.8 (CI 1.0-3.2) for high birth weight and a relative risk of 1.2 (CI 1.0-1.4) for sex ratio (male/female).

CONCLUSIONS

There was no clear association between periconceptional paternal laboratory work and adverse reproductive outcomes, but use of radioactive isotopes showed increased OR for high birth weight in offspring.

The biological effects of diagnostic cardiac imaging on chronically exposed physicians: the importance of being non-ionizing

Ultrasounds and ionizing radiation are extensively used for diagnostic applications in the cardiology clinical practice. This paper reviewed the available information on occupational risk of the cardiologists who perform, every day, cardiac imaging procedures. At the moment, there are no consistent evidence that exposure to medical ultrasound is capable of inducing genetic effects, and representing a serious health hazard for clinical staff. In contrast, exposure to ionizing radiation may result in adverse health effect on clinical cardiologists. Although the current risk estimates are clouded by approximations and extrapolations, most data from cytogenetic studies have reported a detrimental effect on somatic DNA of professionally exposed personnel to chronic low doses of ionizing radiation. Since interventional cardiologists and electro-physiologists have the highest radiation exposure among health professionals, a major awareness is crucial for improving occupational protection. Furthermore, the use of a biological dosimeter could be a reliable tool for the risk quantification on an individual basis.