_Policy, Planning, and Research Working Paper Series_ 7

## 10. **Optimal Export Taxes for Exporters of Perennial Crops**

## Mudassar Imran and Ron Duncan

## **11. The Selection and Use of Pesticides In Bank Financed Public**

# **Health Projes**

## **12. Teacher-NonTeacher Pay Differences In CWte d'lvoire**

## Andre Komenan and Christiaan Grootaert

### Norman Gratz and Bernhard Liese

_Governments relying heavily on export taxes for revenue tend to tax commodity exports more heavily, which is consistent with short-run elasticities of demand and supply. But this makes them more susceptible to losing their market share over the long run._ Since the estimate of the optimal export tax is based on the price elasticity of demand and the price response of the commodity from other sources, should policymakers look at short- or long-term elasticities? The difference is crucial, especially where there is a large gap between the two. Governments weighing the optimal export tax have a choice - accepting lower tax revenues now and reaping higher revenues in the future, or setting their sights on high short-term tax revenues and losing out in the long run.

A comparison of the estimated optimal export tax rates for major developing country producers of cocoa, coffee, tea, and rubber with current tax rates shows the following. When the govemment depends heavilyon the taxforits revenue, it taxes on the basis of the short-run elasticities. This tax rate is much higher than if the long-run elasticities were used, which is usually the case when the taxes are a small proportion of government revenues. But the higher tax rate makes the country susceptible to the loss of market share over time because it reduces the incentive for its own producers (while raising world prices) and encourages the substitution of other commodities by other producers.

Actual export tax rates applied by Cameroon and Nigeria on cocoa and by Sri Lanka on natural rubber were much higher than the optimal rate even when based on short-run elasticity estimates and may well have contributed to reductions in their world market shares.

Recent reductions in export taxes by dominant rubber exporters appear to have exerted downward pressure on world prices, which is consistent with theory.

This paper is a product of the International Commodity Markets Division, International Economics Department. Please contact Audrey Kitson-Walters, room 87-053, extension 33712.

_Where there is no alternative to chemical pesticides, they should be used with environmental and biological methods to cut costs, reduce contamination, and lower the possibility of resistance to the pesticide._ Three methods are available for controlling vector-borne tropical diseases - environmental, biological, and chemical. Environmental control to permanently alter the conditions that allow vectors to breed and develop is the preferred method, but it is not always feasible. Biological control is species-specific and may only be effective under narrow ecological circumstances.

For control of most diseases, therefore, pesticides are the only alternative. Whenever possible, these chemicals should be used along with environmental orbiological methods and the appropriate drug or vaccine. This will cut costs, reduce contamination from pesticides, and lower the possibility of resistance to the pesticide.

Public health officials must be concerned that the compound chosen is safe for the user as well as for inhabitants and domestic animals in the treated area. The method of control must be appropriate for each targeted vector, because there are wide biological differences among species.

Some further considerations in the selection of a pesticide for a public health program to control a particular vector of disease are:

* The chemical must be a narrow spectrum pesticide

* It should be effective in the proposed geographic area

* The target vector should be evaluated to determine if it is resistant to a given chemical

* The proposed pesticide must not pose a hazard to species that are not targeted.

This paper is a product of the Population, Health, and Nutrition Division, Population and Human Resources Department.Please contact Carol Knorr, room S6-137, extension 33611.

_Although teachers in C6te d'Ivoire receive a rent component in their base salaries, it does not put them ahead of nonteachers, who are likely to receive better in-kind benefits, bonuses, and commissions in addition to their salaries._ Because base salaries for teachers in C6te d'Ivoire are higher than wages of workers in other occupations, there is some question about whether teachers are overpaid. But other workers widely receive benefits, bonuses, and commissions and earn the same as teachers. Even allowing for higher educational requirements, different types of teachers, and longer vacations, teachers are not better paid than employees in other fields.

Moreover, while salaries for teachers and other workers having similar educational backgrounds in CBte d'Ivoire are almost the same, nonteachers eam twice as much as teachers having similar lengths of service.

Policymakers should thus be cautious when considering budget cuts that would lower teachers' salaries, cuts certain to make the teaching profession less attractive.

This paper is a product of the Education and Employment Division, Population and Human Resources Department. Please contact Rita Vartamian, room J6011, extension 34678.

## 13. Objectives and **Methods** of a **World Health Survey**

Trudy Harpham and Ian Timaeus _Designing and administering a world health survey will not be easy, but one of the gains from such a survey could be an improvement in the methods governments usetoconductandanalysehealthstudies._ Many developing countries are trying to improve the routine collection of health information by strengthening surveys, censuses, and registration systems. At the international level, too, efforts are under way to provide information on health and health interventions, including statistical reporting programs of the U.N. and the World Bank.

In view of the limited financial re-