Unfortunately, the analysis of chlorinated hydrocarbons is very painstaking work,
in spite of gas chromatography and mass spectrometers, especially if not a certain,
well-known compound is to be analyzed, but unknown components are to be
checked. Only in 1966 was it possible to separate PCB's from DDT and its metabolic
products. Many other surprises will result from improved methods of analysis in the
future.
Organic bound chlorine concentration in seawater from the Dr9bak area, Oslo Fjord,
Norway, has been determined by nondestructive neutron activation analysis to be
40 and 195 ng/l, in two samples (Lunde et al. 1975). However, only 1.1 and 1.6 ng/l
can be explained by gas chromatographic analysis as PCB's. If such figures can be
confirmed, this means that about 99% of the organic bound chlorine is in chlorinated
compounds which are at this moment still unknown to science. They may have their
origin in pollution from Oslo City, or come from biosynthesis within the natural alga
vegetation (Table 37), they may be harmless or toxic. Much has to be learned about
organic chemistry of seawater and marine organisms. Other techniques than gas chromatography should be applied (Ernst 1980).
Besides chlorinated hydrocarbons, there are also other organic compounds which are
so persistent that they are able to accumulate in the environments of the Earth and in
organisms. To these belong the phthalate esters which are mainly used as a softening
agent in synthetic fabric production. Approximately 0.5 million t of them are produced annually. In the muscle tissue of various fish taken from Gulf of Mexico
waters a good distance from land, scientists found an average wet weight concentration of 0.005 mg/kg di-2-ethylhxylphthalate (DEHP) along with dibuthylphthalate
(DBP; Giam et al. 1978). Fortunately, such concentrations in fish can be ignored
from the human health risk point of view, because man takes up DEHP, at present,
in much larger quantities from plastic food packaging than from contaminated food
(Tomiata et al. 1977). But from the environmental health point of view the further
tendency of phthalate ester accumulation has to be carefully monitored.
9.2 What Quantity of Chlorinated Hydrocarbons May Be Tolerated
in Marine Food for Human Consumption?
The World Health Organization (WHO) has established an acceptable daily intake
limit for DDT of 0.3 mg per person, or 0.005 mg/kg body weight 8. On this basis
various countries have different regulations regarding the tolerable concentrations of
DDT and other chlorinated hydrocarbon pesticides in fish and other sea-food. The
Regulation for Maximum Amounts of DDT and other Pesticides in or on Food of
Animal Origin for Human Consumption went into force in the Federal Republic of
Germany in 1974. DDT-like substances are not permitted to exceed concentrations
of 2 mg/kg in sea fish. An exception is made for eel (Anguilla anguilla), salmon
(Salrna salar), and sturgeon (Acipenser sturia). In these fish, 3.5 mg/kg is the limit.
For fish liver and fish oil the limit is set at 5 mg/kg.
8 Where DDT is mentioned in text and figures, the total amount (L DDT) of DDT + DDD + DDE
and other metabolic products is meant. If not otherwise indicated, the concentrations are
relative to wet weight
169
in spite of gas chromatography and mass spectrometers, especially if not a certain,
well-known compound is to be analyzed, but unknown components are to be
checked. Only in 1966 was it possible to separate PCB's from DDT and its metabolic
products. Many other surprises will result from improved methods of analysis in the
future.
Organic bound chlorine concentration in seawater from the Dr9bak area, Oslo Fjord,
Norway, has been determined by nondestructive neutron activation analysis to be
40 and 195 ng/l, in two samples (Lunde et al. 1975). However, only 1.1 and 1.6 ng/l
can be explained by gas chromatographic analysis as PCB's. If such figures can be
confirmed, this means that about 99% of the organic bound chlorine is in chlorinated
compounds which are at this moment still unknown to science. They may have their
origin in pollution from Oslo City, or come from biosynthesis within the natural alga
vegetation (Table 37), they may be harmless or toxic. Much has to be learned about
organic chemistry of seawater and marine organisms. Other techniques than gas chromatography should be applied (Ernst 1980).
Besides chlorinated hydrocarbons, there are also other organic compounds which are
so persistent that they are able to accumulate in the environments of the Earth and in
organisms. To these belong the phthalate esters which are mainly used as a softening
agent in synthetic fabric production. Approximately 0.5 million t of them are produced annually. In the muscle tissue of various fish taken from Gulf of Mexico
waters a good distance from land, scientists found an average wet weight concentration of 0.005 mg/kg di-2-ethylhxylphthalate (DEHP) along with dibuthylphthalate
(DBP; Giam et al. 1978). Fortunately, such concentrations in fish can be ignored
from the human health risk point of view, because man takes up DEHP, at present,
in much larger quantities from plastic food packaging than from contaminated food
(Tomiata et al. 1977). But from the environmental health point of view the further
tendency of phthalate ester accumulation has to be carefully monitored.
9.2 What Quantity of Chlorinated Hydrocarbons May Be Tolerated
in Marine Food for Human Consumption?
The World Health Organization (WHO) has established an acceptable daily intake
limit for DDT of 0.3 mg per person, or 0.005 mg/kg body weight 8. On this basis
various countries have different regulations regarding the tolerable concentrations of
DDT and other chlorinated hydrocarbon pesticides in fish and other sea-food. The
Regulation for Maximum Amounts of DDT and other Pesticides in or on Food of
Animal Origin for Human Consumption went into force in the Federal Republic of
Germany in 1974. DDT-like substances are not permitted to exceed concentrations
of 2 mg/kg in sea fish. An exception is made for eel (Anguilla anguilla), salmon
(Salrna salar), and sturgeon (Acipenser sturia). In these fish, 3.5 mg/kg is the limit.
For fish liver and fish oil the limit is set at 5 mg/kg.
8 Where DDT is mentioned in text and figures, the total amount (L DDT) of DDT + DDD + DDE
and other metabolic products is meant. If not otherwise indicated, the concentrations are
relative to wet weight
169