discovered by Ana Soto and Carlos Sonneschein (OSF
Chapter 8), nonylphenols are estrogen mimics that bind with
the estrogen receptor and provoke estrogenic reponses, both in
vivo and in vitro. Originally thought to be inert, and
indeed used as an "inert" ingredient in many pesticides
because of their surfactant characteristics, nonylphenols have now
been shown to have many biological effects, at least in laboratory
studies (e.g., on
salmon osmoregulatory control).
this publication, Guenther et al. report that nonylphenols
are present in a wide variety of foods bought in German marketplaces,
everything from gooseberry marmalade to liver sausage to chocolate
crumble to doublecream cheese. All samples exampled contained
measurable amounts of nonylphenols. Unfortunately, the work
reveals only the widespread presence of nonylphenols, not how the
food became contaminated. Hence more work will need to be done before
steps can be taken to reduce contamination.
did they do? Geunther et al.purchased 39 samples of adult
foods and 20 baby foods in supermarkets in Germany. Their choice
of foods was guided by a national survey of German food habits,
with an explicit effort made to obtain representatives of each of
the major food types identified in the survey as being common in
German diets. In their purchasing they also explicitly attempted
to buy from the most popular product lines. They also obtained a
sample of breast milk from one lactating 35-yr old woman.
sample of food was stored until analysis at 4°C. With the liquid
foods, the chemical analysis of nonylphenol content was carried
out with the liquid food without further preparation; solids were
first homogenized using a blender. Each sample was put through a
series of steps, first to isolate the organic fraction of the sample
and then to measure the concentrations of different forms of nonylphenols,
using a gas chromatograph/mass spectrophotometer procedure. Prior
to each analysis, the equipment was cleansed with nitric acid to
remove any potentially-contaminating residues.
did they find? Nonylphenol was present in every sample measured,
at levels ranging from 0.1 to 19.4 micrograms/kilogram (µg/kg,
equivalent to parts per billion or ppb):
concentrations of NPs were not only found in fatty food like
e.g. butter (14.4 µg/kg), lard (10.2 µg/kg), or
liver sausage (13.0 µg/kg) but also in nonfatty food
like e.g. marmalade (7.3 µg/kg), apples (19.4 µg/kg),
or tomatoes (18.5 µg/kg)."
following chart from Geunther et al. summarizes contamination
levels the measured across a broad variety of the food sampled:
following graph from Guenther et al. summarizes nonylphenol
levels in milk and chocolate products. The authors make the point
that the milk results presented here demonstrate that fat content
of the foods did not control NP levels: the four different types
of milk in this graph varied in fat content by a factor of >100.
nonylphenols were present in all the baby foods sampled, also:
does it mean? At least in the present food-delivery system of
Germany, it is impossible not to consume small levels of nonylphenols
on a daily basis, from virtually everything food item eaten. There
is no reason to think that German food is substantially different
from any commercially-prepared food anywhere.
data on the average food consumption patterns of Germans, the authors
were able to calculate an expected average daily intake of nonylphenol:
7.5 µg/day for adults and 0.2-1.4 µg/day for infants.
The lower value for infants was for babies exclusively breast-fed.
authors do not point out that average figures can be misleading
when thinking about risk. The averages summarize complicated statistical
distributions, both for the amounts of different food types consumed
and the NP levels within each food type. Some percentage of the
people represented by those averages are unquestionably consuming
far higher levels of NP daily. What percentage will depend upon
the underlying distributions.
this stage it is not possible to identify the exposure pathways
by which these foods became contaminated. Guenther et al.
point out that the foods examined differed substantially in preparation
methods and in packaging, and hence there can't be a single entry
point for nonylphenols into the food supply.
part of it could originate from NPEs which are used as nonionic
surfactants in disinfectants and cleaning agents or as emulsifiers
in pesticide formulations. After application in stables or
food industries and in agriculture, respectively, degradation
of NPEs could lead to the accumulation of NPs in food. In
particular, the high concentrations of NPs in apples and tomatoes
could be consequently attributed to pesticide application.
Then, the lipophilic NPs would be accumulated in the wax coats
of the fruits and vegetables, respectively. Another source
might be plastic packaging materials from which NPs, used
for example in tris(nonylphenol)phosphite as antioxidant,
could migrate into food."