A retrospective cohort study on the effect of the suspected teratogenic pesticide N, N'-methylene-bis-(2-amino-1,3,4-thiadiazole) (MATDA) on outcomes of pregnancy was conducted. The exposed group (6,173 pregnancies) was composed of childbearing women who, during their gestation, consumed rice harvested from a field where MATDA had been applied. The control I group (10,145) came from an adjacent county where MATDA had never been used; the control II group (3,326) consisted of women who had been pregnant previous to the introduction of this pesticide in the same region as the exposed group. The validity of the survey was verified by comparability and data-checking studies. After adjustment for the calendar year, maternal age, and pregnancy order, no significant differences were found in rates of spontaneous abortion, fetal death and stillbirth, birth defects, as well as in sex ratio and birth weight between the study groups. The same result was found in the comparison of individual categories of malformation. The rates of the birth defects were 23.84, 21.49, and 22.78 per 1,000 live births for the exposed, internal, and external control groups, respectively. No dose-response relationship was revealed. The results were consistent with previous reports and indicated the difference between animal experiments and human exposures. Although MATDA is teratogenic in animals, it is clear that the pesticide does not adversely effect outcomes of pregnancy in humans as currently applied.

Acute poisoning among pesticide applicators is still a prominent health hazard in rural areas in developing countries, but published reports are very rare. Registration analysis and descriptive study are helpful in giving guidance for orientation and evaluation of preventive strategies and measures. Data and material from China show that, in circumstances with a well organized grass-roots-level network of primary health care services, poisoning episodes can be prevented through dissemination of information of hazards and provision of prevention training courses. Among pesticide manufacturing workers, especially manual packers of organophosphorus insecticides, there is suggestive evidence of subacute poisoning resulting from continuous low-level exposure. Chronic delayed neuropathy has, rarely, been reported. Further study of the cause of subacute poisoning now requires analytical rather than descriptive investigations. There is still no solid documentation of an association of excess human cancer and the use of chlorinated hydrocarbon insecticides. Phenoxyacetic and chlorophenol herbicides recently have been widely studied for causation of soft tissue sarcoma, non-Hodgkin's leukemia, and lymphoma. Although the evidence at present indicates a positive association, discrepancies in findings and resultant controversy require further study. Epidemiological surveys on the harmful effect of DBCP are quite instructive. Investigations in exposed populations verified and extended the observation in animals as infertility and gender ratio change in the next generation. Adverse reproductive effects of a number of pesticides, particularly birth defects resulting from pesticides (other than those already documented for organomercurials), require further study.