Boron Workers in China

Effects of boron compounds on human reproduction

Because of the high pK_a of boric acid, inorganic borates, when taken up by the human or animal organism, exist in the body almost exclusively in the form of non-dissociated boric acid. Therefore, the variety of inorganic boron compounds is commonly addressed in the toxicological literature as "boron" (B). There is a discussion concerning categorisation of inorganic boron compounds as reproductive toxins. Boron treatment of rats, mice and dogs was dose-dependently associated with testicular toxicity, characterised by inhibited spermiation at lower dose levels and by reduction of epididymal sperm counts at higher dose levels. The NOAEL for such fertility effects of boric acid in male rats (oral feeding, Sprague Dawley strain) was evaluated to be 17.5 mg B/kg bw per day. As far as developmental toxicity is concerned, oral dosing of 9.6 mg B/kg bw daily to female pregnant Sprague Dawley rats remained without effects, with foetal skeletal effects observed at higher doses. Therefore, 9.6 mg B/kg bw (oral dosing) was evaluated as NOAEL for developmental effects of boric acid. The blood level in rats, equivalent to this NOAEL, is 1270 ng B/g. As far as B-exposed humans are concerned, field studies on the effect of boron on human reproduction are possible only in a few boron-rich geographical areas. Published field studies were conducted in China's Liaoning province, the Argentinian Andes and Western Anatolia/Turkey. Particularly relevant are studies on occupationally B-exposed groups, because the potential exposure to boron is much higher in occupational compared to environmental settings. Comparison of estimated daily B exposure levels in humans and actually measured B blood levels confirms the preference of biomonitoring for exposure assessment in environmental and occupational studies. A boron blood level scaling shows that the levels of high occupational B exposures reported in China and in Turkey are compatible. Compared to the experimental B blood levels at boron-related NOAELs for male fertility and for developmental toxicity in rats, the human blood level means of the highest occupational exposure groups in China and in Turkey are lower by factors of > 4 and > 2, respectively. Basically, concentrations of B within the body that exert reproductive toxicity in humans are not reached under the conditions of human normal handling and use, including conditions of extreme occupational exposures. In consequence, all relevant results of studies into human reproductive toxicity of B are basically negative. Considering the effective doses, there is no scientific contradiction between experimental and human results of B reproductive toxicity.

Forming and implementing community advisory boards in low- and middle-income countries: a scoping review

BACKGROUND

Community advisory boards (CABs) have expanded beyond high-income countries (HICs) and play an increasing role in low- and middle-income country (LMIC) research. Much research has examined CABs in HICs, but less is known about CABs in LMICs. The purposes of this scoping review are to examine the creation and implementation of CABs in LMICs, including identifying frequently reported challenges, and to discuss implications for research ethics.

METHODS

We searched five databases (PubMed, Embase, Global Health, Scopus, and Google Scholar) for publications describing or evaluating CABs in LMICs. Two researchers independently reviewed articles for inclusion. Data related to the following aspects of CABs were extracted from included publications: time, country, financial support, research focus, responsibilities, and challenges. Thematic analyses were used to summarize textual data describing challenges.

RESULTS

Our search yielded 2005 citations, 83 of which were deemed eligible for inclusion. Most studies (65) were published between 2010 and 2017. Upper-middle-income countries were more likely to have studies describing CABs, with South Africa (17), China (8), and Thailand (7) having the greatest numbers. The United States National Institutes of Health was the main source of financial support for CABs. Many CABs (53/88, 60%) focused on HIV research. Thirty-four studies reported how CABs influenced the informed consent process for clinical trials or other aspects of research ethics. CAB responsibilities were related to clinical trials, including reviewing study protocols, educating local communities about research activities, and promoting the ethical conduct of research. Challenges faced by CABs included the following: incomplete ethical regulations and guidance; limited knowledge of science among members of communities and CABs; unstable and unbalanced power relationships between researchers and local communities; poor CAB management, including lack of formal participation structures and absence of CAB leadership; competing demands for time that limited participation in CAB activities; and language barriers between research staff and community members. Several challenges reflected shortcomings within the research team.

CONCLUSIONS

Our findings examine the formation and implementation of CABs in LMICs and identify several ethical challenges. These findings suggest the need for further ethics training among CAB members and researchers in LMICs.

Is There an Association Between Extreme Levels of Boron Exposure and Decrease in Y:X Sperm Ratio in Men? Results of an Epidemiological Study

Objectives

A negative association between Y:X sperm ratio and high levels of boron exposure was suggested in an epidemiological study conducted in boron mining areas of China. That study, however, was criticized by many authors due to some weaknesses in the study design. The present epidemiological study was designed to corroborate or refute the above-mentioned negative association between boron exposure and Y:X sperm ratio in men.

Materials and Methods

The study was conducted in a boric acid production zone in Bandırma. One hundred sixty-three male workers voluntarily participated in our study. The workers employed in the boric acid production facilities were assigned as the exposed workers (n=86). The control group was composed of workers employed in the steam power plant, energy supply unit, demineralized water plant, mechanical workshop, etc. (n=77). Blood and semen samples were sampled from the participating workers at the end of the work shift. Y:X sperm ratio in semen samples was determined by fluorescence in situ hybridization. Boron concentrations in semen and blood samples were determined using inductively coupled plasma-mass spectrometry.

Results

Boron-mediated adverse effect on the Y:X sperm ratio was not determined in workers in our study even under extreme occupational exposure conditions. The results of our study refute the negative association between Y:X sperm ratio and high levels of boron exposure that was suggested in a previously published epidemiological study conducted in boron mining areas of China.

Conclusion

The results of our study indicate that boron-mediated adverse effects on the Y:X sperm ratio do not seem possible even under occupational boron exposure conditions.

An overview of boron, lithium, and strontium in human health and profiles of these elements in urine of Japanese

The biological, medical and environmental roles of trace elements have attracted considerable attention over the years. In spite of their relevance in nutritional, occupational and toxicological aspects, there is still a lack of consistent and reliable measurement techniques and reliable information on reference values. In this review our understandings of the urinary profilings of boron, lithium and strontium are summarized and fundamental results obtained in our laboratory are discussed.Over the past decade we have successfully used inductively coupled plasma emission spectrometry for the determination of reference values for urinary concentrations of boron, lithium and strontium. Taking into account the short biological half-life of these elements and the fact that their major excretion route is via the kidney, urine was considered to be a suitable material for monitoring of exposure to these elements. We confirmed that urinary concentrations of boron, lithium and strontium follow a lognormal distribution. The geometric mean reference values and 95% confidence intervals were 798 μg/l (398-1599 μg/l) for boron, 23.5 μg/l (11.0-50.5 μg/l) for lithium and 143.9 μg/l (40.9-505.8 μg/l) for strontium. There were no discrepancies between our values and those previously reported. Our reference values and confidential intervals can be used as guidelines for the health screening of Japanese individuals to evaluate environmental or occupational exposure to these elements.

Community-based participatory research (CBPR) approach to study children's health in China: experiences and reflections

BACKGROUND

Community-based participatory research principles have been successfully applied to public health research in U.S. settings. While there is a long history of collaboration between government and communities in China, to date, community-based participatory research has not been used in children's environmental health studies.

METHOD

This article describes how community-based participatory research principles were applied by an international research group to the China Jintan Child Cohort Study, a longitudinal study of malnutrition and lead exposure on cognitive and neurobehavioral development. Challenges emerged and lessons learned from implementing the study were discussed and recommendations were presented.

CONCLUSION

We conclude that the community-based participatory research model can be applied in conducting and promoting environmental health research in China and researchers should be prepared for special challenges and cultural constraints in the implementation of the research in regards to human subject regulations, information dissemination, and culture.

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.