Pollution might be skewing sex ratio in some parts of Scotland, a new study has found. Researchers said that some areas of the country have witnessed the birth of more baby girls than boys.

According to Stirling University researchers and colleagues, regions with high industrial pollution have "low sex ratio values for population." The team focused on studying the effects of a class of chemicals called "endocrine disruptors." These chemicals disrupt the body's endocrine or hormone system.

Researchers found skewed sex ratio in Eastern Central Scotland.

The study is published in the journal International Journal of Occupational and Environmental Health.

"The sex ratio, particularly declines in male births, can therefore be a sentinel marker for changes in reproductive health or fertility amongst human populations," said Dr Ewan McDonald, the principal investigator, according to a news release. "Our analysis on sex ratio was extensive: over time, regions, neighbourhoods and socio-economic groups across Scotland."

The study was based on data on historical Scottish trends in birth ratios. The research included information on geographical location, social deprivation and air emission levels.

Researchers found that social deprivation wasn't linked to the change in sex ratio. However, the team found a strong connection between decline in number of male babies born in the region and air pollution levels.

According to the study team, their research findings are comparable to studies conducted in industrialized parts of Canada. But, researchers haven't found a cause-and-effect relation between poor sex ratio and pollution.

"The study raises important questions about our knowledge of what may impact on human reproductive health and how we then shape public health policy," said Andrew Watterson, who also involved in the study. "We run faster and faster introducing new products and processes. Yet we do not properly understand how they may affect us."

"We lack full toxicity data sets on many chemicals in our environment but proposed Scottish and English developments for example may introduce more endocrine disruptors. Great care is needed in approving and regulating such developments when we lack the necessary information to assess their risks adequately," Watterson added.

Previous research in a Canadian community had found that thousands of babies who should have been boys were born as girls. A 2007 survey of Greenland and East Russia had shown a similar change in sex ratio.