From John Ray's shorter notes
February 06, 2018
Air pollution delays the age girls start their periods and makes their menstrual cycles more irregular, according to a study
Greenies have been pumping out studies like this for decades. Car exhaust has got to be bad for you! It's got those evil microparticles in it. It does. But are they harmful and at what concentration are they harmful? The study below does not allow those basic questions to be answered.
It did not in fact measure anybody's exposure to the particles. The researchers just looked at where people lived during their childhood. And if that area had a lot of pollution they theorized that people brought up there should have bad health. And they found it was so.
But correlation is not causation and they failed to look at WHY some people lived in more polluted areas. But we know why. Because they were poor. Leafy areas are for rich people. The poor live where they can afford it, beside major roads, industrial areas etc.
So what we are most likely seeing here is that it is the poor who have worse health, which has been known for years.
If the researchers had controlled for income they might have had a story but there seems to be no indication that they did. And the effects they observed were tiny anyway, making it highly likely that any control would wipe them out.
Control for income would only be a first step, however. I set out some other problems with this sort of study a month ago
Journal abstract follows the summary below
Air pollution delays the age girls start their periods, according to the first study of its kind.
Exposure to total suspended particulate (TSP), which are particles circulating in the air that measure 0.05mm, during girls' teenage years also makes their menstrual cycles less regular, a trial found.
TSP, which is largely made up of vehicle exhaust and coal combustion fumes, is thought to disrupt hormone production in people's bodies.
In females, this can cause excessive amounts of male sex hormones, such as testosterone, which the researchers believe could delay or disrupt girls' periods.
Study author Dr Shruthi Mahalingaiah from Boston University, said: 'While air pollution exposures have been linked to cardiovascular and pulmonary disease, this study suggests there may be other systems, such as the reproductive endocrine system, that are affected as well.'
Women exposed to air pollution before getting pregnant are nearly 20 percent more likely to have babies with birth defects, research suggested in January 2018.
Living within 5km of a highly-polluted area one month before conceiving makes women more likely to give birth to babies with defects such as cleft palates or lips, a study by University of Cincinnati found.
For every 0.01mg/m3 increase in fine air particles, birth defects rise by 19 percent, the research adds.
Fine air particles, which weigh less than 0.0025mg, are given out in vehicle exhaust fumes and, when breathed in, become deposited in the lungs where they enter the circulation.
Previous research suggests this causes birth defects as a result of women suffering inflammation and 'internal stress'.
Physicians Committee figures reveal birth defects affect three percent of all babies born in the US.
Around six percent of infants suffer in the UK, according to a report from the British Isles Network of Congenital Anomaly Registers
The researchers analyzed 290,000 babies living in Ohio between 2006 and 2010.
Monthly fine air particle levels were matched to the home addresses of pregnant women before and after they conceived.
How the research was carried out
The researchers analyzed 34,832 women aged between 25 and 42 who were enrolled in the 1989 Nurses' Health Study 2.
They investigated the TSP levels in the air surrounding the study's participants' homes they lived in during high school. This information was obtained from the US Environmental Protection Agency.
The women were asked how old they were when they started their period and how long it took for their cycles to become regular.
Air pollution increases period irregularity
Results further reveal that for every 45 ?g/m3 increase in TSP exposure during high school, girls have an eight percent higher risk of suffering moderate or persistent irregularity.
The researchers defined moderate irregularity as periods that were always erratic during high school or between the ages of 18 and 22.
Persistent irregularity is an inconsistent menstrual cycle both at high school and the ages 18-to-22.
The findings also show that for every 45 ?g/m3 rise in TSP exposure, a girl's risk of producing excessive male hormones increases by up to 11 percent.
Dr Mahalingaiah said: 'While air pollution exposures have been linked to cardiovascular and pulmonary disease, this study suggests there may be other systems, such as the reproductive endocrine system, that are affected as well.'
The findings were published in the journal Human Reproduction.
Perimenarchal air pollution exposure and menstrual disorders
S Mahalingaiah et al
What is the association between perimenarchal exposure to total suspended particulate (TSP) in air, menstrual irregularity phenotypes and time to menstrual cycle regularity?
Exposures to TSP during high school are associated with slightly increased odds of menstrual irregularity and longer time to regularity in high school and early adulthood.
WHAT IS KNOWN ALREADY
The menstrual cycle is responsive to hormonal regulation. Particulate matter air pollution has demonstrated hormonal activity. However, it is not known if air pollution is associated with menstrual cycle regularity.
STUDY DESIGN, SIZE, DURATION
Cross sectional study of 34 832 of the original 116 430 women (29.91%) enrolled in 1989 from the Nurses’ Health Study II (NHSII). The follow-up rate for this analytic sample was 97.76% at the 1991 survey.
PARTICIPANTS/MATERIALS, SETTING, METHODS
Annual averages of TSP were available for each year of high school attendance. We created three case definitions including high school menstrual irregularity and androgen excess. The time to menstrual cycle regularity was reported by participants as <1 year, 1–2 years, 3–4 years, 5 years or longer, or never on the baseline questionnaire. Odds ratios and 95% confidence intervals (CI) were calculated for 45 ?g/m3 increases in TSP exposure, adjusted for risk factors for menstrual irregularity.
MAIN RESULTS AND THE ROLE OF CHANCE
In multivariable adjusted models, we observed that for every 45 ?g/m3 increase in average high school TSP there was an increased odds (95%CI) of 1.08 (1.03–1.14), 1.08 (1.02–1.15) and 1.10 (0.98–1.25) for moderate, persistent, and persistent with androgen excess irregularity phenotypes, respectively. TSP was also associated with a longer time to cycle regularity, with stronger results among women with older ages at menarche and those living in the Northeast or the West.
LIMITATIONS, REASONS FOR CAUTION
The outcomes of menstrual regularity and time to cycle regularity were retrospectively assessed outcomes and may be susceptible to recall bias. There is also the potential for selection bias, as women had to live until 2011 to provide addresses.
WIDER IMPLICATIONS OF THE FINDINGS
Temporal exposure to air pollution in the adolescent and early adulthood window may be especially important, given its association with phenotypes of menstrual irregularity. The data from this study agrees with existing literature regarding air pollution and reproductive tract diseases.
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