New safety alerts for plastic chemicals
In spite of an expensive damage-limitation exercise by the plastics
industry, health worries continue to surface concerning the safety of
phthalates, compounds that are used extensively in plastic and personal-care
products. Two new studies, published within a fortnight of each other,
suggest that phthalates cause liver problems
in babies, and may even be responsible for the steep rise in premature
Around one billion pounds (weight) of phthalates are manufactured every
year, and find their way into PVC and other plastics to make them more
pliable, as well as into toiletries, hair-sprays, perfumes, lubricants and
We absorb phthalates through the skin, by breathing them in and by ingesting
them. Detectable across the surface of the earth, they are global pollutants
(Science, 1981; 211: 163-5), and also form a significant part of the air we
breathe in our own homes (Environ Sci Technol, 1984; 18: 648-52).
The multibillion-dollar phthalate industry is protected by a number of
groups, such as the American Council on Science and Health (ACSH), that were
specially created to safeguard production levels. These bodies claim that
none of the numerous studies carried out has truly established a direct
cause-and-effect relationship between the compounds and health hazards. One
industry lobby group, the European Council for Plasticisers and
Intermediates (ECPI), claims-via the Phthalates Information Centre Europe,
an ECPI-funded initiative-that phthal-ates have been "used for nearly 50
years without a single known case of it having caused any ill health and the
environ-mental effects of phthalates are known to be minimal".
Phthalates and infant health
Nevertheless, these denials fly in the face of a mountain of studies
suggest-ing that phthalates can cause health problems for everyone-but
especially baby boys. The European Commission agreed with the evidence and,
in 2005, banned the use of phthalates in toys for the under-threes, as
infants are much more likely to put these objects into their mouth.
The Commission calls phthalates "toxic substances", and its Scientific
Committee on Toxicity, Ecotoxicity and the Environment (SCTEE) has even said
that other phthalates-including DINP, DIDP and DNOP-may also be "potentially
dangerous to health".
The decision was vindicated recently by two studies that underscore the
dangers of phthalates to newborns and infants. In the first, which tracked
the health of 76 newborns in an intensive care unit in Mannheim, Germany,
the investigators concluded that DEHP, used in intravenous (IV) feeding bags
and tubing, increased the risk of liver damage. Half of all the babies fed
via such IV equipment had liver problems, compared with only 15 per cent of
those given different feeding options (Pediatrics, 2009; 124: 710-6).
However, this problem had already been recognized by the US Food and Drug
Administration (FDA) which, in 2002, recommended the use of non-DEHP feeding
equipment for all those patients most at risk of health problems due to
phthalates leaching into their systems. Apart from newborn babies and
premature infants, small boys should also avoid the chemical as it can
interfere with the reproductive organs.
Indeed, one hospital switched from DEHP IV equipment 10 years ago. Beth
Lyman, a paediatric nutrition nurse at the Children's Mercy Hospital in
Kansas City, MO, has noticed that the number of cases of liver problems has
dropped since using only phthalate-free feeding systems (Associated Press,
27 July 2009).
The chemical has also been blamed for the rise in premature births by 30 per
cent over the past 30 years. One study of 60 pregnant women found that the
30 who delivered within 37 weeks had up to three times the amount of
phthalates in their body compared with those who carried to term (Environ
Health Perspect, 2009; doi: 10.1289/ehp.0800522).
Infants are also exposed through other sources. One study of 163 infants
found nine different phthalates in their urine as a result of exposure to
infant-care lotions, powders and shampoos (Pediatrics, 2008; 121: e260-8).
In fact, the DFG (Deutsche Forsch-ungsgemeinschaft), a German research
foundation, found that people are being exposed to far higher levels than
the so-called TDI, or tolerable daily intake-the highest dose that humans
can absorb without affecting their health-and the exposure levels are
especially high among children (Medical News Today, 20 March 2004).
The problem may be greater than some studies would have us believe. In North
Carolina, the US Environmental Protection Agency found that levels of
phthalates were at their highest in the urine of breastfeeding mothers and,
yet, was hardly detectable in the mothers' blood, saliva or milk-suggesting
that urine concentrations do not accurately reflect phthalate exposure. Nail
polish was the main source of phthalates here (Environ Health Perspect,
2009; 117: 86-92).
The US Centers for Disease Control and Prevention (CDC) found that 5 per
cent of the women in America had up to 45 times more phthalates in their
bodies than researchers had initially estimated. Also, it found phthalates
in virtually every person tested, wth the highest concentrations being found
in women of child-bearing age (NCEH Pub 05-0664, July 2005).
What's more, babies aren't even safe from phthalate exposure in the womb.
One study of 88 babies with low birth weights found that more than 70 per
cent of the mothers had high levels of phthalates in their blood. The
research-ers believed there was a direct causal connection between one
phthalate, DBP, and low birth weight (J Pediatr, 2009; 23 June; e-published
ahead of print).
The fetus is especially vulnerable to phthalate exposure from the mother
because it doesn't have any protective mechanisms, as these only develop
after birth, says researcher Retha Newbold (Reprod Toxicol, 2007; 23:
Male reproductive problems
Prenatal exposure to phthalates can have long-term effects, surfacing only
in adulthood. As phthalates are endocrine disruptors, it is believed that
young boys are especially vulnerable as it interferes with androgen hormone
development, responsible for the production of testosterone.
One study discovered a direct link between phthalate levels in the mother
and later genital developmental prob-lems in her male children. Researchers
from the University of Rochester, in New York, profiled 85 boys and the
pre-natal phthalate levels in their mothers, and found that high levels of
four phthalates correlated with higher-than-expected numbers of
abnormalities in the child's genital development (Environ Health Perspect,
2005; 113: 1056-61).
In one animal study, exposure to high levels of phthalates delayed the onset
of puberty in male rats. Fed four different doses of the phthalate DEHP
every day, those fed the highest dose-900 mg/kg body weight/day-were found
to have the longest delay in reaching puberty (Toxicol Sci, 2009; June 15;
Phthalate exposure also affects sperm production. Researchers at the
Massachusetts General Hospital in Boston, MA, analyzed sperm and urine
samples from 168 healthy adult volunteers, and found that those with the
highest levels of phthalates in their urine also had the most DNA damage to
their sperm (Environ Health Perspect, 2003; 111: 1164-9).
Hypospadias-a defect in which the penis has an abnormally placed opening-is
a relatively common abnormality, and one that may be caused by endocrine
disruptors such as phthalates. Researchers at University College Cork in
471 hypospadias cases with 490 healthy matched controls, and found that the
boys whose mothers were exposed to high levels of phthalates in their
workplace-such as hairdressers, who use hair spray all day long-were nearly
three times more likely to have the condition (Environ Health Perspect,
2009; 117: 303-7).
Other health worries
- Asthma. Phthalate levels in the home could be responsible for
asthma, rhinitis and eczema in children. Researchers at the Swedish National
Testing and Research Institute investigated 400 children, aged between three
and eight years, who were reported to have any of the three conditions. The
scientists took blood samples from the children and dust samples from their
homes, and found a correlation between the phthalate BBzP-found in PVC
flooring-and rhinitis and eczema, while asthma was associated with high
levels of airborne DEHP (Environ Health Perspect, 2004; 112: 1393-7).
- Thyroid function. Phthalates and other industrial chemicals pose a
serious threat to healthy thyroid function, say researchers from University
of Copenhagen in Denmark. Phthalates were included in the list of chemicals
that are known to interfere with healthy thyroid function, thereby leading
to neurological problems (Curr Opin Endocrinol Diabetes Obes, 2009; 21 July;
e-published ahead of print).
- Obesity. Phthalates may well play
a part in the obesity epidemic. Researchers at the
University of Lausanne in Switzerland believe that these agents can
interfere with lipid and carbohydrate metabolism, part of the process that
leads to obesity. The phthalates MEHP and DEHP have even been called
'metabolic disruptors' because they interact with special receptors that
control our metabolism (Mol Cell Endocrinol, 2009; 304: 43-8).
The bottom line
Industry groups and lobbyists have clouded the phthalate safety debate by
claiming that critics have cherry-picked the evidence to show these
in a bad light, and have been overly reliant on animal studies despite the
scant evidence to suggest that the same reactions would be seen in humans.
However, many of the industry's so-called critics are, in fact, independent
researchers from leading research and academic institutes. Also, far from
cherry-picking the evidence, many studies are meta-analyses, where the
findings of many previous studies are evaluated as a whole. It's also a fact
that many more studies are looking at the impact of these agents in humans,
although some still rely on tests using laboratory rats (especially in cases
where the study design would certainly raise ethical issues if carried out
in human infants).
Nevertheless, as is seen with many other environmental pollutants, the
economic model appears to be driving the health issues, with the result that
it's in the interests of Industry and the State to turn a blind eye to what
is clearly a serious health hazard to us all.
Drugs are a major source
Slow-release pharmaceuticals often use phthalates in the enteric coating
designed to dissolve in the stomach, and researchers fear that users of
these drugs are being exposed to dangerously high levels of the chemical.
Researchers from the Harvard School of Public Health were among the first to
be alerted to the potential health hazards when they examined a patient who
had been taking the drug Asacol (mesalazine) for three months for ulcerative
colitis. During that time, the levels of DBP (dibutyl phthalate) in his
urine were twice those found in the worst five-per-cent of cases reported in
the US National Health and Nutrition Examination Survey (NHANES) of
1999-2000. Before taking the drug, his DBP levels had been described as
"unremarkable" (Environ Health Perspect, 2004; 112: 751-3).
After studying this one alarming case, the Harvard researchers widened their
search to include 7999 NHANES 1999-2004 participants who had concentrations
of phthalates in their urine. Of these, six were taking Asacol, and their
DBP levels were 50 times higher than it was for people who weren't taking
the drug. In addition, people taking drugs such as didanosine, omeprazole
and theophylline had levels of DEP (diethyl phthalate) that were
considerably higher than those found in non-drug-users (Environ Health
Perspect, 2009; 117: 185-9).
Vol. 20 06 September 2009