BIOACCUMULATION AND BIOMAGNIFICATION - Marine Pollution: What Everyone Needs to Know - page 156

standards for contaminants. California has stricter require-
ments than the FDA. Consumer Reports published a survey
that revealed PCBs in amounts that could require warning
labels under California's Proposition 65 (a consumer right-to-
know law) in some of the supplements.
How can eating fish or shellfish that have accumulated
HAB toxins cause disease?
Some single celled algae, both dinoflagellates and diatoms,
produce toxins that can accumulate in the food chain and
affect human consumers. Toxin-producing algae are normally
found in the ocean at low concentrations and pose no prob-
lems. However, when they undergo a bloom, often in response
to nutrients (see Chapter 2), it is called a harmful algal bloom
(HAB). Filter-feeding shellfish pump water through their sys-
tems, filtering out and eating algae and other food particles.
When they eat toxic algae, the toxin can accumulate in their
tissues, often without affecting them much. Most cases of
seafood poisoning are in people who ate shellfish that accu-
mulated the toxins. When the bloom subsides, the shellfish
eventually flush the toxin from their systems. In contrast with
chemical pollutants that need to build up in one's system
over a long time, when people eat a single meal or only a few
HAB-contaminated shellfish, acute symptoms start shortly
thereafter.
What is Paralytic shellfish poisoning (PSP)?
Paralytic shellfish poisoning (PSP) is a severe neurological con-
dition caused by eating shellfish contaminated with saxitoxin,
which is produced by the dinoflagellate Alexandrium . Blooms
of Alexandrium are common in New England. Clams, mussels,
oysters, and scallops can accumulate the toxin, as can some
snails. Symptoms include tingling, numbness, burning, giddi-
ness, drowsiness, fever, rash, and staggering. Effects generally