Some of its rhetoric is reminiscent of Chicken Little:
- “Where have all the boys gone?”
- “Millions of males are disappearing.”
- “We’re on the Titanic and we see the iceberg but we just can’t turn the ship.”
- “It may be a threat to the survival of the species.”
The claims behind the rhetoric are that male to female sex ratios at birth are decreasing, sperm quality and fertility are decreasing, and genitourinary birth defects like hypospadias are becoming more common. The film blames environmental chemicals, especially endocrine disruptors, and it claims they are causing “the most rapid period of evolution our species has ever seen” and that this may lead to our extinction.
Decreasing Sex Ratios
Are sex ratios really decreasing? How much? CDC data show that the sex ratio of male to female births in the United States generally declined between 1942 and 1959, increased between 1959 and 1971, and declined from 1971 to 2002. The highest sex ratio occurred in 1946 (1,059 male births per 1,000 female births) and the lowest in 1991 and 2001 (1,046). The numbers show that we currently have (rounded off to the nearest percent) 5% more boys being born than girls.
How does that compare to other countries? The world sex ratio of male births to female births is 1.06. It is 1.0 in Grenada and the Faroe Islands, 1.03 in Guinea, Swaziland, Sierra Leone, Equatorial Guinea, Togo, Ethiopia, Colombia, and several other third world countries,1.06 in the European Union, 1.12 in India and China, 1.15 in Georgia, and 1.17 in Armenia. The lowest reported ratio was 0.863: 863 male births per 1000 female births in the Cayman Islands in 1994.
The film claims that the sex ratio is decreasing in industrialized countries,
presumably due to the greater use of chemicals in those countries. The data do not support that claim. The sex ratio is actually lower in many third world countries, and the current sex ratio in the industrialized EU is high – higher than the 1946 ratio in the US. The sex ratio at birth for most countries is between 1.05 and 1.06. The U.S. sex ratios at birth from 1940–2002 were mostly within this range of variability.
Correlation is not causation, and their claim of a correlation with developed countries is false; and they haven’t established that there is any correlation with chemical exposures either. What other factors might affect sex ratios? A reduced sex ratio at birth has been linked to older age at childbearing and to birth order. Demographic composition is a factor: the sex ratio varies among ethnic groups in the US: “Filipino mothers had the highest sex ratio in any single year (1,128 in 1974) and Japanese mothers had the lowest (985 in 1972). The highest total sex ratio for all years combined was for Chinese (1,074) and Filipino mothers (1,072). The lowest sex ratio for all years combined were observed for black (1,030) and American Indian mothers (1,031).” Other associated factors are increased age of the father, geographic and climatic conditions, lower maternal weight, stress, pesticides, infertility treatments, methylmercury exposure (fish in the diet), and cigarette smoking. The sex ratios in India and China are influenced by the strong preference for male children and the practice of determining sex by ultrasound and aborting female fetuses.
The film highlights Sarnia, Ontario, where surrounding chemical plants are blamed for the sharpest decline in male births ever recorded. Careful statistical analyses are necessary to determine whether such clusters are significant or whether they represent naturally occurring points on one end of a bell curve. Cluster analysis is tricky. The mean ratio for the nation necessarily means that half of communities will have higher and half will have lower ratios. When you strew rice over a grid, some squares will have no grains and others will have many. The prototypical Love Canal incident found clusters of health problems associated with pollution; but even there, skeptics have questioned how many illnesses were truly caused by the chemical exposures, and a followup showed no difference in mortality rates for previous residents.
The film characterizes the Sarnia findings as “the first sign of extinction.” A bit of an exaggeration, don’t you think? The world population is still growing by leaps and bounds. We might be in danger of extinction for a variety of reasons (climate change, nuclear wars, asteroid impacts), but changes in the male/female birth ratios are not high on the list.
The film makes other claims that are highly questionable. It blames chemicals for lower sperm counts, increased infertility, genitourinary birth defects like hypospadias, lower testosterone levels, etc.
Lower sperm counts?
The film claims that young adult males produce half the sperm their fathers did and up to 85% are abnormal.. “change has been sudden and dramatic.” The literature does not bear that out.
This study found a decrease in sperm count. This one found no decrease in sperm count. This one found an increase in sperm count at sperm banks. In Danish sperm donors studied from 1977 to 1995, sperm count increased while motility decreased and there were significant seasonal variations.
In sperm donors in Paris there was a decline in sperm count and motility.
The studies are conflicting. There seems to be a marked geographic variation that might eventually help provide clues to etiology.
What could explain a decrease in sperm quality? The film targets chemicals, and this paperreviews two studies (on maternal smoking and phthalate exposure) that provide
good (though not conclusive) evidence that environmental agents, even at low levels, can alter semen quality. Several other plausible agents are currently being investigated for their ability to alter male reproduction (organochlorine pesticides, bisphenol-A, triazines, etc.) and the number is likely to increase
The authors caution:
Because these exposures are fairly ubiquitous, it is probable that subjects in both these studies have been exposed to low levels of multiple agents. The next challenge, teasing out the separate and combined effects of this “chemical soup,” must be met before concluding that any specific exposure has altered semen quality, let alone caused a worldwide decline in semen quality.
There are many other factors that may contribute to decreases in sperm quality. Heat from saunas, hot baths, tanning beds, tight trousers and underwear, fever, summer weather, and laptop computers. Drugs such as antidepressants, anabolic steroids, and antibiotics. Coffee, marijuana, alcohol, soy products, and cottonseed oil.
Sperm quality varies with the time of day and the method of collection (prior abstinence, masturbation vs. intercourse, length of stimulation before ejaculation). A study in Australiafound an association of lower sperm count with obesity. A study in Tunisia found a decrease in sperm count but not in motility, and it suggested that infection might be a contributing factor in semen quality decline. This one implicated tobacco, alcohol, and varicocoele.
Decreases in sperm count and motility do not necessarily translate into a significant decrease in fertility. In fact, the Australian study cited above was on men whose wives were pregnant. Infertility rates are difficult to measure, and there are conflicting reports. There are no good data showing that infertility has actually increased. Apparent increases could be due to more couples seeking infertility treatment, due to the decreased stigma of publicly admitting the problem, due to increasing age at marriage and first pregnancy, and due to an increase in obesity in the American population.
In 2002, 7% of married couples in which the woman was of reproductive age (2.1 million couples) reported that they had not used contraception for 12 months and the woman had not become pregnant. This is lower than the generally quoted infertility rate of 10%: 1/3 due to male causes, 1/3 due to female causes, and 1/3 to mixed male/female or undetermined causes.
The Mayo Clinic website lists these causes of infertility: Varicocoele, low sperm count and impaired motility, undescended testicle, testosterone deficiency, genetic defects, a history of mumps orchitis, current infections, sexual issues (including erectile dysfunction, premature ejaculation, dyspareunia, psychological factors and the use of lubricants which may be toxic to sperm), retrograde ejaculation, hypospadias, anti-sperm antibodies, cystic fibrosis, emotional stress, malnutrition, cancer and its treatment, alcohol, drugs, injuries, diseases (like diabetes, thyroid disease, kidney disease, Cushing’s syndrome or anemia), age, pesticides and other chemicals, lead exposure, overheating the testicles, cocaine, marijuana, tobacco smoking.
Other studies have suggested that rising infertility rates can be linked to the increasing instance of sexually transmitted diseases, abortion, contraceptive use, and the advanced age at which many women begin to attempt to become pregnant. In Vitro Fertilization (IVF) might eventually increase the rate of infertility in the population by perpetuating the genes of those less likely to conceive naturally.
With all these contributing factors, it is unrealistic and simplistic to focus the blame on chemicals alone. The film interviewed several people. One man said his sperm tests looked OK but his wife didn’t get pregnant. A woman had several miscarriages – doctors could find no reason. The mother of a child with an undescended testicle describes her guilt feelings for “not having done more.” These anecdotes don’t show any causal connection with chemicals. They are not evidence to support the message of the film – they are gratuitously alarming appeals to emotion.
Some women want to get pregnant and can’t; far more don’t want to get pregnant but do. In 2001, half of pregnancies in the United States were unintended. The rate was substantially above average among women aged 18–24, unmarried (particularly cohabiting) women, low-income women, women who had not completed high school and minority women.
Birth Defects – Hypospadias
The film cites a 200% increase in male sexual birth defects: I couldn’t find a source to substantiate that claim. It interviews a wildlife researcher who has found abnormalities in alligators including small genital organs and a male testosterone level equivalent to the normal female levels. A woman comments “Little boys are no different than alligators.” Most of us would beg to differ.
A table on the CDC website tabulates changes in 16 categories of birth defect. Eight of them decreased and 8 increased. For instance, clubfoot decreased more than hypospadias increased. Even if the genital system is more susceptible, if there were a strong influence of environmental chemicals on birth defects, shouldn’t we expect to see a rising trend in most systems?
The true incidence of birth defects is difficult to determine because of inconsistent and incomplete data gathering. The US Birth Defects Monitoring Program tracks rates of birth defects but its website warns:
BDMP data must be interpreted with care but, used as a screening tool, they frequently call attention to areas that need additional study. Variations in incidence may be caused by changes other than those associated with environmental teratogens–for example, chance, diagnostic habits, and reporting procedures. These possible explanations must be considered in seeking the cause of a trend or geographic cluster.
Genetic, nutritional, infectious, and other environmental factors, such as radiation, pharmaceuticals, and toxic chemicals, contribute to the total incidence of birth defects, but the percentage attributable to each is not known. Environmental exposures associated with hypospadias include not only pesticides, dioxin, and living near hazardous waste sites, but also maternal medications (DES, anti-epileptic drugs, cocaine, aspirin), maternal illness (influenza), other maternal factors (in-vitro fertilization using sperm injection into egg, work in leather industry) and paternal factors (working as vehicle mechanics).
Some cases appear to be genetic, with a 7% familial recurrence risk. Another factor is diet. A vegetarian diet is associated with increased risk of hypospadias, likely due to soy and phytoestrogens. In a study in Denmark and Sweden,
a diet during pregnancy lacking both fish and meat was associated with a more than 4-fold increased risk of hypospadias …Boys born to obese women had a more than 2-fold increased risk of hypospadias …Maternal hypertension during pregnancy and absence of maternal nausea increased a boy’s risk of hypospadias 2.0-fold … CONCLUSIONS: A pregnancy diet lacking meat and fish appears to increase the risk of hypospadias in the offspring. Other risk associations were compatible with a role for placental insufficiency in the etiology of hypospadias.
There is even speculation that green tea may increase the risk of birth defects.
Several studies have implicated chemicals: this study linked plasticizers to hypospadias in rats.
But other studies do not seem to implicate chemicals. A study in China found an increased incidence of hypospadias over the previous 10 years, but it was found to be associated with:
poor intrauterine growth, maternal multiple births, living in a rural area, working outdoors and agricultural activities, hepatitis B antigen carrier status, hypertension, and pre-eclampsia of pregnancy.
Prostate gland and testicular development in laboratory animals is fundamentally altered by exposure to estrogenic agents during fetal development. Similar changes in humans would be expected to increase the risk of prostate and testicular cancer later in life. The rate of testicular cancer appears to be rising but epidemiologic studies have failed to show any association with vasectomy, occupational and environmental exposures, or viral illnesses. The risk factors associated with testicular cancer include white race, cryptorchidism, testicular atrophy or dysgenesis, and family history The rates apparently rose, and then stabilized. We don’t know the cause of either the initial increase or the subsequent stabilization.
Endocrine Disruptors and Other Chemicals
The film offers many alarmist claims about chemicals, many of which are vague and/or unsupported by the medical literature. “Some common chemicals are causing profound and permanent damage to growing bodies.” Chemicals are everywhere in our environment – 80,000 of them, 85% of which have never tested for effects on human body and some of which have been tested in adults but not in the more vulnerable children and fetuses. Chemicals are more damaging to boys than to girls. There is danger in our homes, where we are exposed to 1000 synthetic chemicals. Chemicals are in our body and are accumulating. Phthalates are found in almost everyone, and they leach out of toys. Most of the culprits are petrochemical derivatives.
There is legitimate concern that endocrine disruptors may have significant effects on human health. The main suspects are DDT, polychlorinated biphenyls (PCB’s), Bisphenol A (BPA), polybrominated diphenyl ethers (PBDE’s), and phthalates. The evidence is controversial. The first principle of toxicology is “the poison is in the dose.” Many scientists feel that the amounts humans are exposed to are insufficient to cause problems; others have suggested that there is a synergistic effect between small amounts of several toxins.
The film appears to buy into a vague, general “chemicals are bad” mindset. It applauds Health Canada for taking baby bottles with Bisphenol A off the market. It excoriates the US government and chemical manufacturers for allegedly covering up evidence and for saying there is no evidence that any individual has ever been harmed by currently allowable levels of these chemicals. (There isn’t.) They admit that these levels are lower than what would cause problems but they nevertheless “believe” the limits should be lower. This is ideology, not science.
They did not tell viewers that the European Food Safety Authority has evaluated BPA and found no reason to ban it:
The conclusions of the Panel are that after exposure to BPA the human body rapidly metabolises and eliminates the substance. This represents an important metabolic difference compared with rats. EFSA will continue to monitor closely scientific findings regarding BPA and any related health effects.
The risks from endocrine disruptors and other chemicals must be put into perspective. A recent report estimates that 25-33% of the global burden of disease can be attributed to environmental risk factors. Children under 5 years of age seem to bear the largest environmental burden, but the portion of disease due to environmental risks appears to decrease with economic development – just the opposite of what the film claims.
Environmental factors include diet, tobacco, alcohol and many other known risks. Smoking is the most serious environmental risk factor, causing lung cancer, heart attacks, and many other diseases and it is by far the largest preventable cause of death. The number of health problems suspected to be caused by endocrine disruptors pales beside the numbers of deaths known to be caused by smoking. Synthetic pesticides do not seem to be a very significant problem when you consider that 99.99% of pesticides in the American diet are chemicals that plants produce to defend themselves.
So yes, there has been a small decrease in the ratio of male to female births, and it is worth asking why; but we don’t have an answer to the question yet. Some would invoke the precautionary principle: if there is any chance that chemicals are dangerous, we should avoid exposure. The precautionary principle sounds good in theory, but there are many pitfalls in putting it into practice. Unfortunately, when we don’t fully understand the situation, our remedies may be counterproductive. For instance, the World Food Program supplied maize to Africa to stave off starvation. Maize lacks vitamin B3, and now Africa is seeing a resurgence of the vitamin deficiency disease pellagra. If you take Bisphenol A out of products, you have to replace it with something. Avoiding BPA might inadvertently increase our exposure to another hazard or cause harm to the environment. There can be unexpected and unforeseeable consequences to a proposed corrective action. It behooves us to use good science to try to understand what the decreased sex ratios mean before we go off half-cocked assigning blame and applying remedies. In Steven Novella’s excellent article on BPA he concludes:
Given the existing evidence I suspect that there are real but small effects from BPA at current human exposure. These effects may be too small to worry about, but (and here is where most agree) more research is necessary.
This film is irresponsible. It takes a legitimate scientific question and turns it into a 3-ring circus. Instead of informing the public, it distorts the facts to frighten the public. It creates fear of the plastic ducky in the kids’ bathtub. It creates guilt in parents who think they should have been able to protect their children from things like undescended testicles, which as far as we know are not preventable. It encourages paranoia.
Most people get their scientific information from the media. This film is a good example of how unreliable the media can be. Endocrine disruptors and other chemicals may be harming us: we need to continue to investigate that possibility with good science. But we don’t need to panic. Our males are not disappearing.