Multi-factorial influences on sex ratio: a spatio-temporal investigation of endocrine disruptor pollution and neighborhood stress

Abstract

Background:

It is suggested the declining male birth proportion in some industrialized countries is linked to ubiquitous endocrine disruptor exposure. Stress and advanced parental age are determinants which frequently present positive findings. Multi-factorial influences on population sex ratio are rarely explored or tested in research.

Objectives:

To test the hypothesis that dual factors of pollution and population stress affects sex proportion at birth through geographical analysis of Central Scotland.

Methods:

The study incorporates the use of Geographical Information Systems (GIS) tools to overlay modeled point source endocrine disruptor air emissions with “small-area” data on multiple deprivation (a proxy measurement of stress) and birth sex. Historical review of regional sex ratio trends presents additional data on sex ratio in Scotland to consider.

Results:

There was no overall concentration in Central Scotland of low sex ratio neighborhoods with areas where endocrine disruptor air pollution and deprivation or economic stress were high. Historical regional trends in Scotland (from 1973), however, do show significantly lower sex ratio values for populations where industrial air pollution is highest (i.e. Eastern Central Scotland).

Conclusions:

Use of small area data sets and pollution inventories is a potential new method of inquiry for reproductive environmental and health protection monitoring and has produced interesting findings.

Keywords:

• Sex ratio
• Male births
• Endocrine disruption
• Reproductive health
• Air pollution
• Multiple deprivation
• Neighborhood stress
• Maternal age

Acknowledgements

The authors wish to acknowledge the Scottish Environmental Protection Authority for the use of Pollutant Release inventory information. The Scottish Environment Protection Agency reserves all copyright and database rights. The authors also acknowledge the helpful contribution of General Register Office (Scotland), in particular David Shelton, for guidance on appropriate birth statistics.