Vol. 23, No. 6
Publications from the World Health Organization
Dinitro-ortho-Cresol, Environmental Health Criteria No.
220, 2000, xvii + 87 pages (English, with summaries in French and Spanish),
ISBN 92 4 157220 5, CHF 26.-/ USD 23.40; In developing countries: CHF
18.20, Order No. 1160220.
This book evaluates the risks to human and animal health posed by exposure
to dinitro-ortho-cresol, a chemical used for over a century as an acaricide,
larvicide, and ovicide to control the dormant forms of many insects
in orchards. The chemical is also sprayed on potatoes to prevent virus
and disease contamination of the tubers. Although the chemical's use
as a pesticide has been banned in many countries, significant volumes
of obsolete stocks are still found in several parts of the world, especially
in developing countries. Dinitro-ortho-cresol continues to be used in
the plastics industry as an inhibitor of polymerization in styrene and
vinyl aromatic compounds.
Concerning environmental behavior, studies indicate that the chemical
is rapidly biodegraded in soil and has no potential to volatilize when
released to water. Evidence further suggests that uptake by treated
fruit trees or potatoes, leaving residues at harvest time, does not
occur. Food is, therefore, not considered an important source of exposure
for the general population. Occupational exposures during agricultural
spraying and during manufacturing and formulation are regarded as the
principal sources of human exposure. Studies of kinetics and metabolism
demonstrate that absorption through the skin and the ingestion or inhalation
of aerosols are the principal routes of exposure. In agricultural workers,
the skin is the principal route of exposure. The most extensive part
of the report evaluates the results of toxicity studies in laboratory
mammals and in vitro test systems. Short-term dietary administration
decreased body-weight gain in some species, usually without significant
alteration in food consumption. At high doses, adverse effects on the
liver have been observed. A single long-term dietary feeding study produced
no evidence of adverse effects. Data on embryotoxicity, teratogenicity,
mutagenicity, and carcinogenicity were judged inadequate for evaluation.
The evaluation of effects on human health draws on data obtained during
the limited use of dinitro-ortho-cresol in the 1930s as a therapeutic
agent for the treatment of obesity, and on cases of acute poisoning.
Symptoms associated with toxicity include restlessness, flushed skin,
sweating, thirst, deep and rapid respiration, severe increase of body
temperature, and cyanosis leading to collapse, coma, and death. Concerning
adverse effects on occupationally exposed workers, the report cites
a dramatic decline over the last 25 years in reported cases of occupational
intoxication. The decline is attributed to better education of users,
the use of adequate protective equipment, and improvements in application
techniques, equipment, and formulations. The report concludes that,
when used according to registered recommendations, and when measures
for personal protection are followed, exposure to dinitro-ortho-cresol
is reduced to levels that do not cause systemic toxicity.