toxicological profile for malathion - Agency for Toxic Substances and ...

MALATHION 110
3. HEALTH EFFECTS
first 3 days was greater for the emulsifiable concentrate formulation than for unformulated malathion,
suggesting the effect of adjuvants.
3.4.2 Distribution
Most work on distribution relied on radio-labeled malathion. In general, such data represent the
composite data for the parent chemical and metabolites, but in the case of malathion, metabolites are
likely to dominate the chemical profile. This is true both in studies involving extraction and in
autoradiographic work. When analytical techniques such as chromatography were employed, more
specific information can be revealed for individual chemicals. Extremely rapid metabolism of malathion
in certain tissues, but not in others, however, makes it difficult to gain a definitive picture of distribution
of malathion and its metabolites.
3.4.2.1 Inhalation Exposure
No information was located in the literature on distribution of malathion or metabolites following
inhalation exposure.
3.4.2.2 Oral Exposure
A few cases of intentional ingestion of malathion with fatal consequences provide some information on
distribution of malathion and metabolites in humans. In four cases studied by Faragó (1967), aside from
the stomach, intestine, and blood, malathion was found by thin layer chromatography in significant
amounts in the liver and kidneys. In a case of a 53-year-old white female described by Morgade and
Barquet (1982), malathion was found by column and gas chromatographic procedures in the spleen,
adipose tissue, kidney, and brain, but not in the liver shortly after death (specific times of death and
autopsy were not available). Adipose tissue had the most, 76.4 µg/g, whereas the kidney had 17.5 µg/g.
Malaoxon was detected a very low levels in some tissues, although adipose tissue had 8.2 mg/kg. The
metabolites malathion monocarboxylic acid and malaoxon dicarboxylic acid were identified in all tissues;
the monocarboxylic acid was the more abundant, 221 µg/g in bile, 106 µg/g in kidney, and 103 µg/g in
gastric content. Jadhav et al. (1992) used high performance liquid chromatography (HPLC) to examine
six cases in which autopsies were conducted within 24 hours after death; tissues examined included the