[The health problems associated with irrigation with wastewater in Mexico].

Over 85,000 hectares in the Mezquital Valley of central Mexico are irrigated with wastewater. The main crops are fodder and cereal crops. A two cross-sectional survey was carried out to test the impact of exposure to raw wastewater and from storage of that wastewater in reservoirs.

Measurement of insecticides for house spraying.

In view of the economic and operational importance in malaria eradication campaigns of correctly measuring the insecticides used, tests have been made in Mexico to compare the accuracy of two manual procedures, one volumetric and the other gravimetric. For volumetric measurement a calibrated, metal measuring-can of sheet metal is used, and for gravimetric measurement a specially designed Roman balance. Altogether 1022 volumetric and 1411 gravimetric tests were made.