Background and methods
Within the screening program of 2008 it was decided that levels of organic
metabolites should be studied in urine. The reason for focusing on metabolites was:
They reflect internal exposure at the cellular level
The occurrence of metabolites reflects the true individual exposure
Monitoring of metabolite exposure is not prone to external contamination
Many metabolites are more toxic than their parent compounds
Human biomonitoring programs in other countries has to a large degree
focused on metabolites of organic substances in urine
To cover a wide group of exposure pathways, the following substance groups where
included:
Phtalates that mainly reflect exposure from substances in plastic products
(10 metabolites)
PAHs that mostly reflect exposure to airborne contaminants originating
from combustion (15 metabolites)
Organophosphate pesticides that mostly reflects exposure to food stuff in
Sweden (6 metabolites)
Metals that reflect a wide variety of exposure pathways (Al, Cd, Co, Cr,
Cu, Hg, Mn, Mo, Ni, Pb, Zn, As)
To complement the exposure based screening of urine, an effects based screening
was also included where the urine samples were tested for endocrine (estrogen)
disturbing effects using the YES (Yeast Estrogen Screening assay) in vitro method.
The urine sampling was part of a larger sampling campaign performed by the
institute of environmental medicine, at Karolinska Institutet with a focus on
Cadmium. Within this sampling program a number of women were randomly chosen
to receive a letter asking for their participation in the present study. From this larger
subset 20 women were randomly chosen for inclusion in the present study. As part of
the study, the women answered a questionnaire with a number of exposure related
questions.
The objectives of the project were to:
To broadly assess exposure levels of some important contaminant groups
in the Swedish female population by examining a small subset consisting
of 20 females.
To compare exposure levels of these substance groups to exposure levels
in other countries
To statistically investigate the co-occurrence of different metabolites and
metals in urine
To explore the connection between endocrine disturbing effects and the
exposure levels of these substance groups
Results
The main conclusions from this study were:
1. Urine is clearly a good matrix for human biomonitoring of organic
chemicals and metals given the high prevalence of detection and the good
correlations seen between many metabolites.
2. PAH and phthalate metabolites originating from many(most) of the
important mother compounds as well as metals were very prevalent in the
urine of the women and the levels were generally variable.
3. Metabolites of organophosphorous pesticides were not prevalent
4. No connection could be found between exposure related .information given
by the women and metabolite and metal levels in urine.
5. Levels of PAH and phthalate metabolites are in general similar to reference
concentrations in USA, Germany and Holland.
6. Levels of the phthalate metabolites MiBP and MiNP were clearly above
levels in the USA indicating a higher exposure to the phthalates DBP and
DINP
7. Levels of the metabolite Mono-ethyl phthalate (MEP) were clearly lower in
the present study compared to levels in USA and below levels in Holland,
indicating lower exposure to the phthalate DEP in Sweden.
8. Levels of organophosphate pesticide metabolites were clearly below levels
seen in USA and Germany
9. Levels of metals were generally below levels seen in USA and Germany
10. The urinary levels of most phthalate metabolites correlated clearly
11. The levels of PAH metabolites also correlated, but not as clearly as for
phthalate metabolites
12. No connection could be established between endocrine disturbing effects
measured with an in vitro test, and urinary levels of metabolites and metals.
A partial explanation may be the presence of natural hormones with
endocrine inducing properties in women’s urine.
The following recommendations were given:
5. Follow-up studies focusing on PAH metabolites and phthalate metabolites
are suggested. These studies should contain larger groups of women and/or
men so that exposure factors influencing metabolite concentration in urine
could be established.
6. The number of metabolites in follow up studies could be reduced based on
the results from this study.
7. There is no further need for organophosphate pesticide metabolite
screening studies in urine.
8. Further screening studies of metals in urine could also be of interest
although the levels seen in this study were gebwerally low compared to
other countries