Science 4-6 Crossword
                                        
                                        
                                        
                                        
                                        
                                        
                                        
                                        
                                        
                                        
                                        
                                        
                                        
                                        
                                        
                                        
                                        
                                        
                                        
                                        
                                        
                                        
                                        
                                        
                                        
                                        
                                        
                                        
 
 
Down: 1) broken down by natural means like a chemical reaction. eg- fertillizers or sewage.2) breakdowsn slowly or not at all. eg- pesticides, petroleum products, heavy metal3) any alteration of the environment producing harmful conditions4) symptons occur after a chemical accumulates to a level over time5) serious symptons occur after one exposure9) is the ability of a chemical to cause a harm to an organsim11) lethal dose so which means to the dose of a chemical that will kill 50 percent of the population. Across: 6) 7) not all individuals react the same way to a chemical, establishing risk is often difficult.8) any material or form that causes harm to a living organism.10) lower the oxygen level which kills aquatic animals.
 

 

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