**2. Identifying hazards**

492 Toxicity and Drug Testing

of phenol/ formaldehyde resins (Bakelite) and in the production of octylphenol ethoxylates, and used in the formulation of printing inks and in

DDT is an insecticide which was used extensively on crops, but is now only used in a few countries against the malaria-bearing mosquito. DDT and DDE last in the soil for a very long time, potentially for hundreds of years. Unfortunately, due to this persistence, it is still found in some produce, such as vegetables, fish and liver. DDE is also found as a persistent contaminant in our bodies. The DDT breakdown product or metabolite, p,p'-DDE, is

tyre manufacture

able to block testosterone.

and spinach.

Ketoconazole Ketoconazole is as an anti-fungal

Permethrin

melons and oranges

and vegetables.

Linuron and diuron are herbicide used to control weeds on hard surfaces such as roads, railway tracks and in crops and forestry. It has been detected in tap water and as a residue in vagetables such as carrots, parsnips

These are all fungicide used on fruits

These are all insecticides are used, for example, on apples, plums, barries, peas, sweet corn and cereals. Those have been found as a contaminant of fruit, such as oranges and grapes etc.

product in pharmaceuticals to treat fungal infections of the skin.

Some pyrethroid pesticides such as

beta-cyfluthrin, cypermethrin, are still in use, with for example, the latter found as a residue in apples, beans,

Common uses and routes of exposure The effects on male

reproductive system

a. Hormone mimicking

b. Reduce synthesis of

a. Anti-androgenic

a. Blocks testosterone action b. Reduce testosterone

d. Feminize male offspring.

a. Blocks testosterone action b. Reduce testosterone

a. Blocks testosterone action b. Reduce testosterone

a. Blocks testosterone action b. Reduce testosterone

properties

synthesis

synthesis

synthesis

synthesis

c. Anti-androgenic properties

c. Anti-androgenic properties

c. Anti-androgenic properties

activities

testosterone

Common environmental

(break-down product DDE).

Toxicants

DDT

Linuron Diuron

Vinclozolin Procymidone Iprodione Prochloroz Fenarimol

Fenarimol Fenitrothion Chlorpyrifos-methyl

Pyrethroid pesticides

Permethrin Beta-cyfluthrin Cypermethrin

A discrepancy exists between the number of chemicals in commerce (approximately 84,000) and the number that have been evaluated in model species for reproductive toxicity potential (4,000) (U.S. EPA 1998a and 1998b). It is not feasible to allocate additional resources to test the 80,000 or so untested chemicals through traditional testing protocols, particularly given that about 2,000 new chemicals are introduced into commerce each year (U.S. EPA 1998). Instead, new, more rapid methods are needed to screen large numbers of chemicals and to identify those that are potential reproductive hazards. In the near term, top priorities will be to develop the most promising alternative models and to test their ability to appropriately classify the toxicity of sets of known toxicants and non-toxicants.
